Canonical Voices

Posts tagged with 'ubuntu'

Daniel Holbach

Ubuntu 16.04 is out!

Ubuntu 16.04 – yet another LTS?

Ubuntu 16.04 LTS, aka the Xenial Xerus, has just been released. It’s incredible that it’s already the 24th Ubuntu release and the 6th LTS release. If you have been around for a while and need a blast from the past, check out this video:

Click here to view it on youtube. It’s available in /usr/share/example-content on a default desktop install as well.

You would think that after such a long time releases get somewhat inflationary and less important and while I’d very likely always say on release day “yes, this one is the best of all so far”, Ubuntu 16.04 is indeed very special to me.

Snappy snappy snappy

Among the many pieces of goodness to come to your way is the snapd package. It’s installed by default on many flavours of Ubuntu including Ubuntu Desktop and is your snappy connection to myApps.

Snappy Ubuntu Core 2.0 landing just in time for the 16.04 LTS release only happened due to the great and very hard work of many teams and individuals. I also see it as the implementation of lots of feedback we have been getting from third party app developers, ISVs and upstream projects over the years. Basically what all of them wanted was in a nutshell: a solid Ubuntu base, flexibility in handling their app and the relevant stack, independence from distro freezes, dead-simple packaging, bullet-proof upgrades and rollbacks, and an app store model established with the rise of the smartphones. Snappy Ubuntu Core is exactly that and more. What it also brings to Ubuntu is a clear isolation between apps and a universal trust model.

As most of you know, I’ve been trying to teach people how to do packaging for Ubuntu for years and it continued to improve and get easier, but all in all, it still is hard to get right. snapcraft makes this so much easier. It’s just beautiful. If you have been doing some packaging in the past, just take a look at some of the examples.

Landing a well-working and stable snapd with clear-cut and stable set of APIs was the most important aspect, especially considering that almost everyone will be basing their work on 16.04 LTS, which is going to be supported for five years. This includes being able to use snapcraft on the LTS.

Today you can build a snap, upload it to the store using snapcraft upload, having it automatically reviewed and published by the store and Desktop users can install it on their system. This brings you in a position where you can easily share your software with millions of users, without having to wait for somebody to upload it to the distro for you, without having your users add yet another PPA, etc.

So, what’s still missing? Quite a few things actually. Because you have to bundle your dependencies, packages are still quite big. This will change as soon as the specifics of OS and library snaps are figured out. Apart from that many new interfaces will need to be added to make Ubuntu Core really useful and versatile. There are also still a few bugs which need figuring out.

If you generally like what you’re reading here, come and talk to us. Introduce yourselves, talk to us and we’ll figure out if anything you need it still missing.

If you’re curious you can also check out some blog posts written by people who worked on this relentlessly in the last weeks:

Thanks a lot everyone – I thoroughly enjoyed working with you on this and I’m looking forward to all the great things we are going to deliver together!

Bring your friends, bring your questions!

The Community team moved the weekly Ubuntu Community Q&A to be tomorrow, Friday 2016-04-22 15:00 UTC on as usual. If you have questions, tune in and bring your friends as well!

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Dustin Kirkland

I'm thrilled to introduce Docker 1.10.3, available on every Ubuntu architecture, for Ubuntu 16.04 LTS, and announce the General Availability of Ubuntu Fan Networking!

That's Ubuntu Docker binaries and Ubuntu Docker images for:
  • armhf (rpi2, et al. IoT devices)
  • arm64 (Cavium, et al. servers)
  • i686 (does anyone seriously still run 32-bit intel servers?)
  • amd64 (most servers and clouds under the sun)
  • ppc64el (OpenPower and IBM POWER8 machine learning super servers)
  • s390x (IBM System Z LinuxOne super uptime mainframes)
That's Docker-Docker-Docker-Docker-Docker-Docker, from the smallest Raspberry Pi's to the biggest IBM mainframes in the world today!  Never more than one 'sudo apt install' command away.

Moreover, we now have Docker running inside of LXD!  Containers all the way down.  Application containers (e.g. Docker), inside of Machine containers (e.g. LXD), inside of Virtual Machines (e.g. KVM), inside of a public or private cloud (e.g. Azure, OpenStack), running on bare metal (take your pick).

Let's have a look at launching a Docker application container inside of a LXD machine container:

kirkland@x250:~⟫ lxc launch ubuntu-daily:x -p default -p docker
Creating magical-damion
Starting magical-damion
kirkland@x250:~⟫ lxc list | grep RUNNING
| magical-damion | RUNNING | (eth0) | | PERSISTENT | 0 |
kirkland@x250:~⟫ lxc exec magical-damion bash
root@magical-damion:~# apt update >/dev/null 2>&1 ; apt install -y >/dev/null 2>&1
root@magical-damion:~# docker run -it ubuntu bash
Unable to find image 'ubuntu:latest' locally
latest: Pulling from library/ubuntu
759d6771041e: Pull complete
8836b825667b: Pull complete
c2f5e51744e6: Pull complete
a3ed95caeb02: Pull complete
Digest: sha256:b4dbab2d8029edddfe494f42183de20b7e2e871a424ff16ffe7b15a31f102536
Status: Downloaded newer image for ubuntu:latest
root@0577bd7d5db1:/# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 02:42:ac:11:00:02
inet addr: Bcast: Mask:
inet6 addr: fe80::42:acff:fe11:2/64 Scope:Link
RX packets:16 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1296 (1.2 KB) TX bytes:648 (648.0 B)

Oh, and let's talk about networking...  We're also pleased to announce the general availability of Ubuntu Fan networking -- specially designed to connect all of your Docker containers spread across your network.  Ubuntu's Fan networking feature is an easy way to make every Docker container on your local network easily addressable by every other Docker host and container on the same network.  It's high performance, super simple, utterly deterministic, and we've tested it on every major public cloud as well as OpenStack and our private networks.

Simply installing Ubuntu's Docker package will also install the ubuntu-fan package, which provides an interactive setup script, fanatic, should you choose to join the Fan.  Simply run 'sudo fanatic' and answer the questions.  You can trivially revert your Fan networking setup easily with 'sudo fanatic deconfigure'.

kirkland@x250:~$ sudo fanatic 
Welcome to the fanatic fan networking wizard. This will help you set
up an example fan network and optionally configure docker and/or LXD to
use this network. See fanatic(1) for more details.
Configure fan underlay (hit return to accept, or specify alternative) []:
Configure fan overlay (hit return to accept, or specify alternative) []:
Create LXD networking for underlay: overlay: [Yn]: n
Create docker networking for underlay: overlay: [Yn]: Y
Test docker networking for underlay: overlay:
(NOTE: potentially triggers large image downloads) [Yn]: Y
local docker test: creating test container ...
test master: ping test ( ...
test slave: ping test ( ...
test master: ping test ... PASS
test master: short data test ( -> ...
test slave: ping test ... PASS
test slave: short data test ( -> ...
test master: short data ... PASS
test slave: short data ... PASS
test slave: long data test ( -> ...
test master: long data test ( -> ...
test master: long data ... PASS
test slave: long data ... PASS
local docker test: destroying test container ...
local docker test: test complete PASS (master=0 slave=0)
This host IP address:

I've run 'sudo fanatic' here on a couple of machines on my network -- x250 ( and masterbr (, and now I'm going to launch a Docker container on each of those two machines, obtain each IP address on the Fan (250.x.y.z), install iperf, and test the connectivity and bandwidth between each of them (on my gigabit home network).  You'll see that we'll get 900mbps+ of throughput:

kirkland@x250:~⟫ sudo docker run -it ubuntu bash
root@c22cf0d8e1f7:/# apt update >/dev/null 2>&1 ; apt install -y iperf >/dev/null 2>&1
root@c22cf0d8e1f7:/# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 02:42:fa:00:2d:00
inet addr: Bcast: Mask:
inet6 addr: fe80::42:faff:fe00:2d00/64 Scope:Link
RX packets:6423 errors:0 dropped:0 overruns:0 frame:0
TX packets:4120 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:22065202 (22.0 MB) TX bytes:227225 (227.2 KB)

root@c22cf0d8e1f7:/# iperf -c
multicast ttl failed: Invalid argument
Client connecting to, TCP port 5001
TCP window size: 45.0 KByte (default)
[ 3] local port 54274 connected with port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 1.05 GBytes 902 Mbits/sec

And the second machine:
kirkland@masterbr:~⟫ sudo docker run -it ubuntu bash
root@effc8fe2513d:/# apt update >/dev/null 2>&1 ; apt install -y iperf >/dev/null 2>&1
root@effc8fe2513d:/# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 02:42:fa:00:08:00
inet addr: Bcast: Mask:
inet6 addr: fe80::42:faff:fe00:800/64 Scope:Link
RX packets:7659 errors:0 dropped:0 overruns:0 frame:0
TX packets:3433 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:22131852 (22.1 MB) TX bytes:189875 (189.8 KB)

root@effc8fe2513d:/# iperf -s
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
[ 4] local port 5001 connected with port 54274
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 1.05 GBytes 899 Mbits/sec

Finally, let's have another long hard look at the image from the top of this post.  Download it in full resolution to study very carefully what's happening here, because it's pretty [redacted] amazing!

Here, we have a Byobu session, split into 6 panes (Shift-F2 5x Times, Shift-F8 6x times).  In each pane, we have an SSH session to Ubuntu 16.04 LTS servers spread across 6 different architectures -- armhf, arm64, i686, amd64, ppc64el, and s390x.  I used the Shift-F9 key to simultaneously run the same commands in each and every window.  Here are the commands I ran:

lxc launch ubuntu-daily:x -p default -p docker
lxc list | grep RUNNING
uname -a
dpkg -l | grep
sudo docker images | grep -m1 ubuntu
sudo docker run -it ubuntu bash
apt update >/dev/null 2>&1 ; apt install -y net-tools >/dev/null 2>&1
ifconfig eth0

That's right.  We just launched Ubuntu LXD containers, as well as Docker containers against every Ubuntu 16.04 LTS architecture.  How's that for Ubuntu everywhere!?!

Ubuntu 16.04 LTS will be one hell of a release!


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Dustin Kirkland

I happen to have a full mirror of the entire Ubuntu Xenial archive here on a local SSD, and I took the opportunity to run a few numbers...
  • 6: This is our 6th Ubuntu LTS
    • 6.06, 8.04, 10.04, 12.04, 14.04, 16.04
  • 7: With Ubuntu 16.04 LTS, we're supporting 7 CPU architectures
    • armhf, arm64, i386, amd64, powerpc, ppc64el, s390x
  • 25,671: Ubuntu 16.04 LTS is comprised of 25,671 source packages
    • main, universe, restricted, multiverse
  • 150,562+: Over 150,562 (and counting!) cloud instances of Xenial have launched to date
    • and we haven't even officially released yet!
  • 216,475: A complete archive of all binary .deb packages in Ubuntu 16.04 LTS consists of 216,475 debs.
    • 24,803 arch independent
    • 27,159 armhf
    • 26,845 arm64
    • 28,730 i386
    • 28,902 amd64
    • 27,061 powerpc
    • 26,837 ppc64el
    • 26,138 s390x
  • 1,426,792,926: A total line count of all source packages in Ubuntu 16.04 LTS using cloc yields 1,426,792,926 total lines of source code
  • 250,478,341,568: A complete archive all debs, all architectures in Ubuntu 16.04 LTS requires 250GB of disk space
Yes, that's 1.4 billion lines of source code comprising the entire Ubuntu 16.04 LTS archive.  What an amazing achievement of open source development!

Perhaps my fellow nerds here might be interested in a breakdown of all 1.4 billion lines across 25K source packages, and throughout 176 different programming languages, as measured by Al Danial's cloc utility.  Interesting data!

You can see the full list here.  What further insight can you glean?


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Dustin Kirkland

On July 7, 2010, I received the above email.  In hindsight, this note effectively changed the landscape of cloud computing forever.  I was one of 3 Canonical employees in attendance (Nick Barcet, Neil Levine) and among a number former colleagues (Theirry Carrez, Soren Hansen, Rick Clark) at the first OpenStack Design Summit at the Omni hotel in Austin, Texas, in July of 2010.

These are the only pictures I snapped with my phone (metadata says it was an HTC Hero) of the event, which, almost unbelievably fit entirely within a single conference room :-)

The "fishbowl" round table discussion format was modeled after Ubuntu Developer Summits.

It was so much fun to see so many unfamiliar, non-Ubuntu people using the fishbowl discussion format.

Also borrowed from Ubuntu Developer Summits was the collaborative, community-sourced note taking in Etherpad-Lite.

Breakfast, in the beautiful Omni lobby.

Lots of natural light, but thankfully, air conditioned.  By the way, does anyone have pictures from the 120oF Whole Foods roof top event?

My, my, my, how far we've come in 6 short years!

This month's OpenStack Summit returns to Austin, Texas, and fills the entire Austin Convention Center, and overflows into at least two nearby hotels, with 5,000+ OpenStack developers, users, and enthusiasts!

In fact, if you're reading this post on, you're being served by Wordpress and MySQL hosted on a production Ubuntu OpenStack at Canonical.

Welcome back home, OpenStack!


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Dustin Kirkland

As announced last week, Microsoft and Canonical have worked together to bring Ubuntu's userspace natively into Windows 10.

As of today, Windows 10 Insiders can now take Ubuntu on Windows for a test drive!  Here's how...

1) You need to have a system running today's 64-bit build of Windows 10 (Build 14316).

2) To do so, you may need to enroll into the Windows Insider program here,

3) You need to notify your Windows desktop that you're a Windows Insider, under "System Settings --> Advanced Windows Update options"

4) You need to set your update ambition to the far right, also known as "the fast ring".

5) You need to enable "developer mode", as this new feature is very pointedly directed specifically at developers.

6) You need to check for updates, apply all updates, and restart.

7) You need to turn on the new Windows feature, "Windows Subsystem for Linux (Beta)".  Note (again) that you need a 64-bit version of Windows!  Without that, you won't see the new option.

8) You need to reboot again.  (Windows sure has a fetish for rebooting!)

9) You press the start button and type "bash".

10) The first time you run "bash.exe", you'll accept the terms of service, download Ubuntu, and then you're off and running!

If you screw something up, and you want to start over, simply open a Windows command shell, and run: lxrun /uninstall /full and then just run bash again.

For bonus points, you might also like to enable the Ubuntu monospace font in your console.  Here's how!

a) Download the Ubuntu monospace font, from

b) Install the Ubuntu monospace font, by opening the zip file you downloaded, finding UbuntuMono-R.ttf, double clicking on it, and then clicking Install.

c) Enable the Ubuntu monospace font for the command console in the Windows registry.  Open regedit and find this key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Console\TrueTypeFont and add a new string value name "000" with value data "Ubuntu Mono"

d) Edit your command console preferences to enable the Ubuntu monospace font.


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Dustin Kirkland

This makes me so incredibly happy!

Here's how...

First, start with a fully up-to-date Ubuntu 16.04 LTS desktop.

sudo apt update
sudo apt dist-upgrade -y

Then, install dconf-editor.

sudo apt install -y dconf-editor

Launch dconf-editor and find the "launcher" key and change it to "bottom".


For good measure, I triggered a reboot, to make sure my changes stuck.  And voila!  Beauty!


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Michael Hall

Somehow I missed the fact that I never wrote Community Donations report for Q3 2015. I only realized it because it’s time for me to start working on Q4. Sorry for the oversight, but that report is now published.

The next report should be out soon, in the mean time you can look at all of the past reports so see the great things we’ve been able to do with and for the Ubuntu community through this program. Everybody who has recieved these funds have used them to contribute to the project in one way or another, and we appreciate all of their work.

As you may notice, we’ve been regularly paying out more than we’ve been getting in donations. While we’ve had a carry-over balance ever since we started this program, that balance is running down. If you like the things we’ve been able to support with this program, please consider sending it a contribution and helping us spread the word about it.


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Dustin Kirkland

Update: Here's how to get started using Ubuntu on Windows

See also Scott Hanselman's blog here
I'm in San Francisco this week, attending Microsoft's Build developer conference, as a sponsored guest of Microsoft.

That's perhaps a bit odd for me, as I hadn't used Windows in nearly 16 years.  But that changed a few months ago, as I embarked on a super secret (and totally mind boggling!) project between Microsoft and Canonical, as unveiled today in a demo during Kevin Gallo's opening keynote of the Build conference....

An Ubuntu user space and bash shell, running natively in a Windows 10 cmd.exe console!

Did you get that?!?  Don't worry, it took me a few laps around that track, before I fully comprehended it when I first heard such crazy talk a few months ago :-)

Here's let's break it down slowly...
  1. Windows 10 users
  2. Can open the Windows Start menu
  3. And type "bash" [enter]
  4. Which opens a cmd.exe console
  5. Running Ubuntu's /bin/bash
  6. With full access to all of Ubuntu user space
  7. Yes, that means apt, ssh, rsync, find, grep, awk, sed, sortxargs, md5sum, gpg, curl, wget, apache, mysql, python, perl, ruby, php, gcc, tar, vim, emacs, diff, patch...
  8. And most of the tens of thousands binary packages available in the Ubuntu archives!
"Right, so just Ubuntu running in a virtual machine?"  Nope!  This isn't a virtual machine at all.  There's no Linux kernel booting in a VM under a hypervisor.  It's just the Ubuntu user space.

"Ah, okay, so this is Ubuntu in a container then?"  Nope!  This isn't a container either.  It's native Ubuntu binaries running directly in Windows.

"Hum, well it's like cygwin perhaps?"  Nope!  Cygwin includes open source utilities are recompiled from source to run natively in Windows.  Here, we're talking about bit-for-bit, checksum-for-checksum Ubuntu ELF binaries running directly in Windows.

[long pause]

"So maybe something like a Linux emulator?"  Now you're getting warmer!  A team of sharp developers at Microsoft has been hard at work adapting some Microsoft research technology to basically perform real time translation of Linux syscalls into Windows OS syscalls.  Linux geeks can think of it sort of the inverse of "wine" -- Ubuntu binaries running natively in Windows.  Microsoft calls it their "Windows Subsystem for Linux".  (No, it's not open source at this time.)

Oh, and it's totally shit hot!  The sysbench utility is showing nearly equivalent cpu, memory, and io performance.

So as part of the engineering work, I needed to wrap the stock Ubuntu root filesystem into a Windows application package (.appx) file for suitable upload to the Windows Store.  That required me to use Microsoft Visual Studio to clone a sample application, edit a few dozen XML files, create a bunch of icon .png's of various sizes, and so on.

Not being Windows developer, I struggled and fought with Visual Studio on this Windows desktop for a few hours, until I was about ready to smash my coffee mug through the damn screen!

Instead, I pressed the Windows key, typed "bash", hit enter.  Then I found the sample application directory in /mnt/c/Users/Kirkland/Downloads, and copied it using "cp -a".  I used find | xargs | rename to update a bunch of filenames.  And a quick grep | xargs | sed to comprehensively search and replace s/SampleApp/UbuntuOnWindows/. And Ubuntu's convert utility quickly resized a bunch of icons.   Then I let Visual Studio do its thing, compiling the package and uploading to the Windows Store.  Voila!

Did you catch that bit about /mnt/c...  That's pretty cool...  All of your Windows drives, like C: are mounted read/write directly under /mnt.  And, vice versa, you can see all of your Ubuntu filesystem from Windows Explorer in C:\Users\Kirkland\AppData\Local\Lxss\rootfs\

Meanwhile, I also needed to ssh over to some of my other Ubuntu systems to get some work done.  No need for Putty!  Just ssh directly from within the Ubuntu shell.

Of course apt install and upgrade as expected.

Is everything working exactly as expected?  No, not quite.  Not yet, at least.  The vast majority of the LTP passes and works well.  But there are some imperfections still, especially around tty's an the vt100.  My beloved byobu, screen, and tmux don't quite work yet, but they're getting close!

And while the current image is Ubuntu 14.04 LTS, we're expecting to see Ubuntu 16.04 LTS replacing Ubuntu 14.04 in the Windows Store very, very soon.

Finally, I imagine some of you -- long time Windows and Ubuntu users alike -- are still wondering, perhaps, "Why?!?"  Having dedicated most of the past two decades of my career to free and open source software, this is an almost surreal endorsement by Microsoft on the importance of open source to developers.  Indeed, what a fantastic opportunity to bridge the world of free and open source technology directly into any Windows 10 desktop on the planet.  And what a wonderful vector into learning and using more Ubuntu and Linux in public clouds like Azure.  From Microsoft's perspective, a variety of surveys and user studies have pointed to bash and Linux tools -- very specifically, Ubuntu -- be available in Windows, and without resource-heavy full virtualization.

So if you're a Windows Insider and have access to the early beta of this technology, we certainly hope you'll try it out!  Let us know what you think!

If you want to hear more, hopefully you'll tune into the Channel 9 Panel discussion at 16:30 PDT on March 30, 2016.


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Dustin Kirkland

Still have questions about Ubuntu on Windows?
Watch this Channel 9 session, recorded live at Build this week, hosted by Scott Hanselman, with questions answered by Windows kernel developers Russ Alexander, Ben Hillis, and myself representing Canonical and Ubuntu!

For fun, watch the crowd develop in the background over the 30 minute session!

And here's another recorded session with a demo by Rich Turner and Russ Alexander.  The real light bulb goes off at about 8:01.


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Michael Hall

As most you you know by now, Ubuntu 16.04 will be dropping the old Ubuntu Software Center in favor of the newer Gnome Software as the graphical front-end to both the Ubuntu archives and 3rd party application store.

Gnome Software

Gnome Software provides a lot of the same enhancements over simple package managers that USC did, and it does this using a new metadata format standard called AppStream. While much of the needed AppStream data can be extracted from the existing packages in the archives, sometimes that’s not sufficient, and that’s when we need people to help fill the gaps.

It turns out that the bulk of the missing or incorrect data is caused by the application icons being used by app packages. While most apps already have an icon, it was never strictly enforced before, and the size and format allowed by the desktop specs was more lenient than what’s needed now.  These lower resolution icons might have been fine for a menu item, but they don’t work very well for a nice, beautiful App Store interface like Gnome Software. And that’s where you can help!

Don’t worry, contributing icons isn’t hard, and it doesn’t require any knowledge of programming or packing to do. Best of all, you’ll not only be helping Ubuntu, but you’ll also be contributing to any other distro that uses the AppStream standard too! In the steps below I will walk you through the process of finding an app in need, getting the correct icon for it, and contributing it to the upstream project and Ubuntu.

1) Pick an App

Because the AppStream data is being automatically extracted from the contents of existing packages, we are able to tell which apps are in need of new icons, and we’ve generated a list of them, sorted by popularity (based on PopCon stats) so you can prioritize your contributions to where they will help the most users. To start working on one, first click the “Create” link to file a new bug report against the package in Ubuntu. Then replace that link in the wiki with a link to your new bug, and put your name in the “Claimed” column so that others know you’ve already started work on it.

Apps with Icon ErrorsNote that a package can contain multiple .desktop files, each of which has it’s own icon, and your bug report will be specific to just that one metadata file. You will also need to be a member of the ~ubuntu-etherpad team (or sub-team like ~ubuntumembers) in order to edit the wiki, you will be asked to verify that membership as part of the login process with Ubuntu SSO.

2) Verify that an AppStream icon is needed

While the extraction process is capable of identifying what packages have a missing or unsupported image in them, it’s not always smart enough to know which packages should have this AppStream data in the first place. So before you get started working on icons, it’s best to first make sure that the metadata file you picked should be part of the AppStream index in the first place.

Because AppStream was designed to be application-centric, the metadata extraction process only looks at those with Type=Application in their .desktop file. It will also ignore any .desktop files with NoDisplay=True in them. If you find a file in the list that shouldn’t be indexed by AppStream, chances are one or both of these values are set incorrectly. In that case you should change your bug description to state that, rather than attaching an icon to it.

3) Contact Upstream

Since there is nothing Ubuntu-specific about AppStream data or icons, you really should be sending your contribution upstream to the originating project. Not only is this best for Ubuntu (carrying patches wastes resources), but it’s just the right thing to do in the open source community. So the after you’ve chosen an app to work on and verfied that it does in fact need a new icon for AppStream, the very next thing you should do is start talking to the upstream project developers.

Start by letting them know that you want to contribute to their project so that it integrates better with AppStream enabled stores (you can reference these Guidelines if they’re not familiar with it), and opening a similar bug report in their bug tracker if they don’t have one already. Finally, be sure to include a link to that upstream bug report in the Ubuntu bug you opened previously so that the Ubuntu developers know the work is also going into upstream to (your contribute might be rejected otherwise).

4) Find or Create an Icon

Chances are the upstream developers already have an icon that meets the AppStream requirements, so ask them about it before trying to find one on your own. If not, look for existing artwork assets that can be used as a logo, and remember that it needs to be at least 64×64 pixels (this is where SVGs are ideal, as they can be exported to any size). Whatever you use, make sure that it matches the application’s current branding, we’re not out to create a new logo for them after all. If you do create a new image file, you will need to make it available under the CC-BY-SA license.

While AppStream only requires a 64×64 pixel image, many desktops (including Unity) will benefit from having even higher resolution icons, and it’s always easier to scale them down than up. So if you have the option, try to provide a 256×256 icon image (or again, just an SVG).

5) Submit your icon

Now that you’ve found (or created) an appropriate icon, it’s time to get it into both the upstream project and Ubuntu. Because each upstream will be different in how they want you to do that, you will need to ask them for guidance (and possibly assistance) in order to do that. Just make sure that you update the upstream bug report with your work, so that the Ubuntu developers can see that it’s been done.

Ubuntu 16.04 has already synced with Debian, so it’s too late for these changes in the upstream project to make their way into this release. In order to get them into 16.04, the Ubuntu packages will have to carry a patch until the changes that land in upstream have the time to make their way into the Ubuntu archives. That’s why it’s so important to get your contribution accepted into the upstream project first, the Ubuntu developers want to know that the patches to their packages will eventually be replaced by the same change from upstream.

attach_file_to_bugTo submit your image to Ubuntu, all you need to do is attach the image file to the bug report you created way back in step #1.

launchpad-subscribeThen, subscribe the “ubuntu-sponsors” team to the bug, these are the Ubuntu developers who will review and apply your icon to the target package, and get it into the Ubuntu archives.

6) Talk about it!

Congratulations, you’ve just made a contribution that is likely to affect millions of people and benefit the entire open source community! That’s something to celebrate, so take to Twitter, Google+, Facebook or your own blog and talk about it. Not only is it good to see people doing these kinds of contributions, it’s also highly motivating to others who might not otherwise get involved. So share your experience, help others who want to do the same, and if you enjoyed it feel free to grab another app from the list and do it again.

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Nicholas Skaggs


The joys of Spring (or Fall for our friends in the Southern Hemisphere) are now upon us. The change of seasons spurs us to implement our own changes, to start anew. It's a time to reflect on the past, appreciate it, and then do a little Spring cleaning.

As I write this post to you, I'm doing my own reflecting. It's been quite a journey we've undertaken within the QA community. It's not always been easy, but I think we are poised for even greater success with Xenial than Trusty and Precise LTS's. We have continued ramping up our quality efforts to test new platforms, such as the phone and IOT devices, while also implementing automated testing via things like autopkgtest and autopilot. Nevertheless, the desktop images have continued to release like clockwork. We're testing more things, more often, while still managing to raise our quality bar.

I want to thank all of the volunteers who've helped make each of those releases a reality. Oftentimes quality can be a background job, with thank you's going unsaid, while complaints are easy to find. Truly, it's been wonderful learning and hacking on quality efforts with you. So thank you!

So if this post sounds a bit like a farewell, that's because it is. At least in a way. Moving forward, I'll be transitioning to working on a new challenge. Don't worry, I'm keeping my QA hat on, and staying firmly within the realm of ubuntu! However, the time has come to try my hand at a different side of ubuntu. That's right, it's time to head to the last frontier, juju!

I'll be working on improving the quality story for juju, but I believe juju has real opportunities to enable the testing story within ubuntu too. I'm looking forward to the new challenges, and sharing best practices. We're all working on ubuntu at it's heart, no matter our focus.

Moving forward, I'll still be around in my usual haunts. You'll still be able to poke me on IRC, or send me a mail, and I'm certainly still going to be watching what happens within quality with interest. That said, you are much more likely to find me discussing juju, servers and charms in #juju.

As with anything, please feel free to contact me directly if you have any concerns or questions. I plan to wind down my involvement during the next few weeks. I'll be handing off any lingering project roles, and stepping down gracefully. Ubuntu 'Y' will begin anew, with fresh challenges and fresh opportunities. I know there are folks waiting to tackle them!

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Dustin Kirkland

We at Canonical have conducted a legal review, including discussion with the industry's leading software freedom legal counsel, of the licenses that apply to the Linux kernel and to ZFS.

And in doing so, we have concluded that we are acting within the rights granted and in compliance with their terms of both of those licenses.  Others have independently achieved the same conclusion.  Differing opinions exist, but please bear in mind that these are opinions.

While the CDDL and GPLv2 are both "copyleft" licenses, they have different scope.  The CDDL applies to all files under the CDDL, while the GPLv2 applies to derivative works.

The CDDL cannot apply to the Linux kernel because zfs.ko is a self-contained file system module -- the kernel itself is quite obviously not a derivative work of this new file system.

And zfs.ko, as a self-contained file system module, is clearly not a derivative work of the Linux kernel but rather quite obviously a derivative work of OpenZFS and OpenSolaris.  Equivalent exceptions have existed for many years, for various other stand alone, self-contained, non-GPL kernel modules.

Our conclusion is good for Ubuntu users, good for Linux, and good for all of free and open source software.

As we have already reached the conclusion, we are not interested in debating license compatibility, but of course welcome the opportunity to discuss the technology.


EDIT: This post was updated to link to the supportive position paper from Eben Moglen of the SFLC, an amicus brief from James Bottomley, as well as the contrarian position from Bradley Kuhn and the SFC.

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Dustin Kirkland

I had the opportunity to speak at Container World 2016 in Santa Clara yesterday.  Thanks in part to the Netflix guys who preceded me, the room was absolutely packed!

You can download a PDF of my slides here, or flip through them embedded below.

I'd really encourage you to try the demo instructions of LXD toward the end!


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Dustin Kirkland

Ubuntu 16.04 LTS (Xenial) is only a few short weeks away, and with it comes one of the most exciting new features Linux has seen in a very long time...

ZFS -- baked directly into Ubuntu -- supported by Canonical.

What is ZFS?

ZFS is a combination of a volume manager (like LVM) and a filesystem (like ext4, xfs, or btrfs).

ZFS one of the most beloved features of Solaris, universally coveted by every Linux sysadmin with a Solaris background.  To our delight, we're happy to make to OpenZFS available on every Ubuntu system.  Ubuntu's reference guide for ZFS can be found here, and these are a few of the killer features:
  • snapshots
  • copy-on-write cloning
  • continuous integrity checking against data corruption
  • automatic repair
  • efficient data compression.
These features truly make ZFS the perfect filesystem for containers.

What does "support" mean?

  • You'll find zfs.ko automatically built and installed on your Ubuntu systems.  No more DKMS-built modules!
$ locate zfs.ko
  • You'll see the module loaded automatically if you use it.

$ lsmod | grep zfs
zfs 2801664 11
zunicode 331776 1 zfs
zcommon 57344 1 zfs
znvpair 90112 2 zfs,zcommon
spl 102400 3 zfs,zcommon,znvpair
zavl 16384 1 zfs

  • The user space zfsutils-linux package will be included in Ubuntu Main, with security updates provided by Canonical (as soon as this MIR is completed).
  • As always, industry leading, enterprise class technical support is available from Canonical with Ubuntu Advantage services.

How do I get started?

It's really quite simple!  Here's a few commands to get you up and running with ZFS and LXD in 60 seconds or less.

First, make sure you're running Ubuntu 16.04 (Xenial).

$ head -n1 /etc/issue
Ubuntu Xenial Xerus (development branch) \n \l

Now, let's install lxd and zfsutils-linux, if you haven't already:

$ sudo apt install lxd zfsutils-linux

Next, let's use the interactive lxd init command to setup LXD and ZFS.  In the example below, I'm simply using a sparse, loopback file for the ZFS pool.  For best results (and what I use on my laptop and production servers), it's best to use a raw SSD partition or device.

$ sudo lxd init
Name of the storage backend to use (dir or zfs): zfs
Create a new ZFS pool (yes/no)? yes
Name of the new ZFS pool: lxd
Would you like to use an existing block device (yes/no)? no
Size in GB of the new loop device (1GB minimum): 2
Would you like LXD to be available over the network (yes/no)? no
LXD has been successfully configured.

We can check our ZFS pool now:

$ sudo zpool list
lxd 1.98G 450K 1.98G - 0% 0% 1.00x ONLINE -

$ sudo zpool status
pool: lxd
state: ONLINE
scan: none requested

lxd ONLINE 0 0 0
/var/lib/lxd/zfs.img ONLINE 0 0 0
errors: No known data errors

$ lxc config get storage.zfs_pool_name
storage.zfs_pool_name: lxd

Finally, let's import the Ubuntu LXD image, and launch a few containers.  Note how fast containers launch, which is enabled by the ZFS cloning and copy-on-write features:

$ newgrp lxd
$ lxd-images import ubuntu --alias ubuntu
Downloading the GPG key for
Progress: 48 %
Validating the GPG signature of /tmp/tmpa71cw5wl/download.json.asc
Downloading the image.
Image manifest:
Image imported as: 54c8caac1f61901ed86c68f24af5f5d3672bdc62c71d04f06df3a59e95684473
Setup alias: ubuntu

$ for i in $(seq 1 5); do lxc launch ubuntu; done
$ lxc list
| discordant-loria | RUNNING | (eth0) | | NO | 0 |
| fictive-noble | RUNNING | (eth0) | | NO | 0 |
| interprotoplasmic-essie | RUNNING | (eth0) | | NO | 0 |
| nondamaging-cain | RUNNING | (eth0) | | NO | 0 |
| untreasurable-efrain | RUNNING | (eth0) | | NO | 0 |

Super easy, right?


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Nicholas Skaggs

Prepping for a Summer of Code!

The time to apply is here! Ubuntu has applied for GSOC 2016, but we need project ideas for prospective students, and mentors to mentor them.

What is GSOC?
GSOC stands for Google Summer of Code. The event brings together university students and open source organizations like Ubuntu. It happens over the course of the summer, and mentors mentor students on a one to one basis. Mentors give project ideas, and students select them, pairing up with the mentor to make the idea a reality.

I'll be a mentor!
Mentors need to be around to help a student from May - August. You'll be mentoring a student on the project you propose, so you'll need to be capable of completing the project. As the time commitment is long, it's helpful to have a friend who can pitch in if needed. We've put together all the information you need to know as a mentor on community.u.c, including links to some mentoring guides. This will help give you more details about what to expect.

I'm in. What do I need to do?
To make sure you ideas are included in our application, you need to have them on the Ideas wiki by February 19th, 2016. When you are ready, simply add your idea. It's that simple. Assuming we are accepted as an organization, students will read our ideas, and we'll have a period of time to finalize the details with interested students.

I have a question!
If you have questions about what all this mentoring might entail, feel free to reach out to myself or anyone on the community team. This is a great way to make some needed ideas a reality and grow the community at the same time!

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Nicholas Skaggs

Google Code In 2015: Complete!

Google Code In 2015 is now complete! Overall, we had a total of 215 students finish more than 500 tasks for ubuntu! The students made contributions to documentation, created wallpapers and other art, fixed Unity 7 issues, hacked on the core apps for the phone, performed tests, wrote automated and manual tests, and worked on tools like the qatracker. A big thank you to all of the students and mentors who helped out.

Here's our winners!

 * Daniyaal Rasheed
 * Matthew Allen

And our Finalists

 * Evan McIntire
 * Girish Rawat
 * Malena Vasquez Currie

The students amazed everyone, myself included, with the level and skill they displayed in there work. You all should be very proud. It was lovely to have you as part of the community, and I've been delighted to see some of your faces sticking around and still contributing! Thank you, and welcome to the community!

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    Dustin Kirkland

    There's no shortage of excitement, controversy, and readership, any time you can work "Docker" into a headline these days.  Perhaps a bit like "Donald Trump", but for CIO tech blogs and IT news -- a real hot button.  Hey, look, I even did it myself in the title of this post!

    Sometimes an article even starts out about CoreOS, but gets diverted into a discussion about Docker, like this one, where shykes (Docker's founder and CTO) announced that Docker's default image would be moving away from Ubuntu to Alpine Linux.

    I have personally been Canonical's business and technical point of contact with Docker Inc, since September of 2013, when I co-presented at an OpenStack Meetup in Austin, Texas, with Ben Golub and Nick Stinemates of Docker.  I can tell you that, along with most of the rest of the Docker community, this casual declaration in an unrelated Hacker News thread, came as a surprise to nearly all of us!

    Docker's default container image is certainly Docker's decision to make.  But it would be prudent to examine at a few facts:

    (1) Check DockerHub and you may notice that while Busybox (Alpine Linux) has surpassed Ubuntu in the number downloads (66M to 40M), Ubuntu is still by far the most "popular" by number of "stars" -- likes, favorites, +1's, whatever, (3.2K to 499).

    (2) Ubuntu's compressed, minimal root tarball is 59 MB, which is what is downloaded over the Internet.  That's different from the 188 MB uncompressed root filesystem, which has been quoted a number of times in the press.

    (3) The real magic of Docker is such that you only ever download that base image, one time!  And you only store one copy of the uncompressed root filesystem on your disk! Just once, sudo docker pull ubuntu, on your laptop at home or work, and then launch thousands of images at a coffee shop or airport lounge with its spotty wifi.  Build derivative images, FROM ubuntu, etc. and you only ever store the incremental differences.

    Actually, I encourage you to test that out yourself...  I just launched a t2.micro -- Amazon's cheapest instance type with the lowest networking bandwidth.  It took 15.938s to sudo apt install  And it took 9.230s to sudo docker pull ubuntu.  It takes less time to download Ubuntu than to install Docker!

    ubuntu@ip-172-30-0-129:~⟫ time sudo apt install -y
    real 0m15.938s
    user 0m2.146s
    sys 0m0.913s

    As compared to...

    ubuntu@ip-172-30-0-129:~⟫ time sudo docker pull ubuntu
    latest: Pulling from ubuntu
    f15ce52fc004: Pull complete
    c4fae638e7ce: Pull complete
    a4c5be5b6e59: Pull complete
    8693db7e8a00: Pull complete
    ubuntu:latest: The image you are pulling has been verified. Important: image verification is a tech preview feature and should not be relied on to provide security.
    Digest: sha256:457b05828bdb5dcc044d93d042863fba3f2158ae249a6db5ae3934307c757c54
    Status: Downloaded newer image for ubuntu:latest
    real 0m9.230s
    user 0m0.021s
    sys 0m0.016s

    Now, sure, it takes even less than that to download Alpine Linux (0.747s by my test), but again you only ever do that once!  After you have your initial image, launching Docker containers take the exact same amount of time (0.233s) and identical storage differences.  See:

    ubuntu@ip-172-30-0-129:/tmp/docker⟫ time sudo docker run alpine /bin/true
    real 0m0.233s
    user 0m0.014s
    sys 0m0.001s
    ubuntu@ip-172-30-0-129:/tmp/docker⟫ time sudo docker run ubuntu /bin/true
    real 0m0.234s
    user 0m0.012s
    sys 0m0.002s

    (4) I regularly communicate sincere, warm congratulations to our friends at Docker Inc, on its continued growth.  shykes publicly mentioned the hiring of the maintainer of Alpine Linux in that Hacker News post.  As a long time Linux distro developer myself, I have tons of respect for everyone involved in building a high quality Linux distribution.  In fact, Canonical employs over 700 people, in 44 countries, working around the clock, all calendar year, to make Ubuntu the world's most popular Linux OS.  Importantly, that includes a dedicated security team that has an outstanding track record over the last 12 years, keeping Ubuntu servers, clouds, desktops, laptops, tablets, and phones up-to-date and protected against the latest security vulnerabilities.  I don't know personally Natanael, but I'm intimately aware of what a spectacular amount of work it is to maintain and secure an OS distribution, as it makes its way into enterprise and production deployments.  Good luck!

    (5) There are currently 5,854 packages available via apk in Alpine Linux (sudo docker run alpine apk search -v).  There are 8,862 packages in Ubuntu Main (officially supported by Canonical), and 53,150 binary packages across all of Ubuntu Main, Universe, Restricted, and Multiverse, supported by the greater Ubuntu community.  Nearly all 50,000+ packages are updated every 6 months, on time, every time, and we release an LTS version of Ubuntu and the best of open source software in the world every 2 years.  Like clockwork.  Choice.  Velocity.  Stability.  That's what Ubuntu brings.

    Docker holds a special place in the Ubuntu ecosystem, and Ubuntu has been instrumental in Docker's growth over the last 3 years.  Where we go from here, is largely up to the cross-section of our two vibrant communities.

    And so I ask you honestly...what do you want to see?  How would you like to see Docker and Ubuntu operate together?

    I'm Canonical's Product Manager for Ubuntu Server, I'm responsible for Canonical's relationship with Docker Inc, and I will read absolutely every comment posted below.


    p.s. I'm speaking at Container Summit in New York City today, and wrote this post from the top of the (inspiring!) One World Observatory at the World Trade Center this morning.  Please come up and talk to me, if you want to share your thoughts (at Container Summit, not the One World Observatory)!

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    Daniel Holbach

    It’s been a while since our last Snappy Clinic, so we asked for your input on which topics to cover. Thanks for the feedback so far.

    In our next session Sergio Schvezov is going to talk about what’s new in Snapcraft and the changes in the 2.x series. Be there and you are going to be up-to-date on how to publish your software on Snappy Ubuntu Core. There will be time for questions afterwards.

    Join us on the 12th February 2016 at 16:00 UTC on

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    Dustin Kirkland

    People of earth, waving at Saturn, courtesy of NASA.
    “It Doesn't Look Like Ubuntu Reached Its Goal Of 200 Million Users This Year”, says Michael Larabel of Phoronix, in a post that it seems he's been itching to post for months.

    Why the negativity?!? Are you sure? Did you count all of them?

    No one has.

    How many people in the world use Ubuntu?

    Actually, no one can count all of the Ubuntu users in the world!

    Canonical, unlike Apple, Microsoft, Red Hat, or Google, does not require each user to register their installation of Ubuntu.

    Of course, you can buy laptops preloaded with Ubuntu from Dell, HP, Lenovo, and Asus.  And there are millions of them out there.  And you can buy servers powered by Ubuntu from IBM, Dell, HP, Cisco, Lenovo, Quanta, and compatible with the OpenCompute Project.

    In 2011, hardware sales might have been how Mark Shuttleworth hoped to reach 200M Ubuntu users by 2015.

    But in reality, hundreds of millions of PCs, servers, devices, virtual machines, and containers have booted Ubuntu to date!

    Let's look at some facts...
    • Docker users have launched Ubuntu images over 35.5 million times.
    • HashiCorp's Vagrant images of Ubuntu 14.04 LTS 64-bit have been downloaded 10 million times.
    • At least 20 million unique instances of Ubuntu have launched in public clouds, private clouds, and bare metal in 2015 itself.
      • That's Ubuntu in clouds like AWS, Microsoft Azure, Google Compute Engine, Rackspace, Oracle Cloud, VMware, and others.
      • And that's Ubuntu in private clouds like OpenStack.
      • And Ubuntu at scale on bare metal with MAAS, often managed with Chef.
    • In fact, over 2 million new Ubuntu cloud instances launched in November 2015.
      • That's 67,000 new Ubuntu cloud instances launched per day.
      • That's 2,800 new Ubuntu cloud instances launched every hour.
      • That's 46 new Ubuntu cloud instances launched every minute.
      • That's nearly one new Ubuntu cloud instance launched every single second of every single day in November 2015.
    • And then there are Ubuntu phones from Meizu.
    • And more Ubuntu phones from BQ.
    • Of course, anyone can install Ubuntu on their Google Nexus tablet or phone.
    • Or buy a converged tablet/desktop preinstalled with Ubuntu from BQ.
    • Oh, and the Tesla entertainment system?  All electric Ubuntu.
    • Google's self-driving cars?  They're self-driven by Ubuntu.
    • George Hotz's home-made self-driving car?  It's a homebrewed Ubuntu autopilot.
    • Snappy Ubuntu downloads and updates for Raspberry Pi's and Beagle Bone Blacks -- the response has been tremendous.  Download numbers are astounding.
    • Drones, robots, network switches, smart devices, the Internet of Things.  More Snappy Ubuntu.
    • How about Walmart?  Everyday low prices.  Everyday Ubuntu.  Lots and lots of Ubuntu.
    • Are you orchestrating containers with Kubernetes or Apache Mesos?  There's plenty of Ubuntu in there.
    • Kicking PaaS with Cloud Foundry?  App instances are Ubuntu LXC containers.  Pivotal has lots of serious users.
    • And Heroku?  You bet your PaaS those hosted application containers are Ubuntu.  Plenty of serious users here too.
    • Tianhe-2, the world's largest super computer.  Merely 80,000 Xeons, 1.4 TB of memory, 12.4 PB of disk, all number crunching on Ubuntu.
    • Ever watch a movie on Netflix?  You were served by Ubuntu.
    • Ever hitch a ride with Uber or Lyft?  Your mobile app is talking to Ubuntu servers on the backend.
    • Did you enjoy watching The Hobbit?  Hunger Games?  Avengers?  Avatar?  All rendered on Ubuntu at WETA Digital.  Among many others.
    • Do you use Instagram?  Say cheese!
    • Listen to Spotify?  Music to my ears...
    • Doing a deal on Wall Street?  Ubuntu is serious business for Bloomberg.
    • Paypal, Dropbox, Snapchat, Pinterest, Reddit. Airbnb.  Yep.  More Ubuntu.
    • Wikipedia and Wikimedia, among the busiest sites on the Internet with 8 - 18 billion page views per month, are hosted on Ubuntu.
    How many "users" of Ubuntu are there ultimately?  I bet there are over a billion people today, using Ubuntu -- both directly and indirectly.  Without a doubt, there are over a billion people on the planet benefiting from the services, security, and availability of Ubuntu today.
    • More people use Ubuntu than we know.
    • More people use Ubuntu than you know.
    • More people use Ubuntu than they know.
    More people use Ubuntu than anyone actually knows.

    Because of who we all are.


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    David Henningsson

    13 ways to PulseAudio

    All roads lead to Rome, but PulseAudio is not far behind! In fact, how the PulseAudio client library determines how to try to connect to the PulseAudio server has no less than 13 different steps. Here they are, in priority order:

    1) As an application developer, you can specify a server string in your call to pa_context_connect. If you do that, that’s the server string used, nothing else.

    2) If the PULSE_SERVER environment variable is set, that’s the server string used, and nothing else.

    3) Next, it goes to X to check if there is an x11 property named PULSE_SERVER. If there is, that’s the server string, nothing else. (There is also a PulseAudio module called module-x11-publish that sets this property. It is loaded by the start-pulseaudio-x11 script.)

    4) It also checks client.conf, if such a file is found, for the default-server key. If that’s present, that’s the server string.

    So, if none of the four methods above gives any result, several items will be merged and tried in order.

    First up is trying to connect to a user-level PulseAudio, which means finding the right path where the UNIX socket exists. That in turn has several steps, in priority order:

    5) If the PULSE_RUNTIME_PATH environment variable is set, that’s the path.

    6) Otherwise, if the XDG_RUNTIME_DIR environment variable is set, the path is the “pulse” subdirectory below the directory specified in XDG_RUNTIME_DIR.

    7) If not, and the “.pulse” directory exists in the current user’s home directory, that’s the path. (This is for historical reasons – a few years ago PulseAudio switched from “.pulse” to using XDG compliant directories, but ignoring “.pulse” would throw away some settings on upgrade.)

    8) Failing that, if XDG_CONFIG_HOME environment variable is set, the path is the “pulse” subdirectory to the directory specified in XDG_CONFIG_HOME.

    9) Still no path? Then fall back to using the “.config/pulse” subdirectory below the current user’s home directory.

    Okay, so maybe we can connect to the UNIX socket inside that user-level PulseAudio path. But if it does not work, there are still a few more things to try:

    10) Using a path of a system-level PulseAudio server. This directory is /var/run/pulse on Ubuntu (and probably most other distributions), or /usr/local/var/run/pulse in case you compiled PulseAudio from source yourself.

    11) By checking client.conf for the key “auto-connect-localhost”. If so, also try connecting to tcp4:…

    12) …and tcp6:[::1], too. Of course we cannot leave IPv6-only systems behind.

    13) As the last straw of hope, the library checks client.conf for the key “auto-connect-display”. If it’s set, it checks the DISPLAY environment variable, and if it finds a hostname (i e, something before the “:”), then that host will be tried too.

    To summarise, first the client library checks for a server string in step 1-4, if there is none, it makes a server string – out of one item from steps 5-9, and then up to four more items from steps 10-13.

    And that’s all. If you ever want to customize how you connect to a PulseAudio server, you have a smorgasbord of options to choose from!

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