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Posts tagged with 'technical'


Juju, maas and agent-name

While working on a procedure with colleagues, I ran into an issue that I prefer to document somewhere. Since my blog has been sleeping for close to a year, I thought I’d put it here.

I was running a set of tests on a version of juju that will resemble 1.16.4. This version, as each one after 1.16.2 implement the agent-name identifier that is, as I understand it, used to discriminate between multiple bootstrapped environments.

I had a bootstrapped environment on a maas 1.4 server (1.4+bzr1693+dfsg-0ubuntu2~ctools0) with a few services running on two machines. Many hours of testing led us to identify that even though juju was using agent-name, it appeared that maas was not.

After upgrading to the latest and greatest version of maas (1.4+bzr1693+dfsg-0ubuntu2.2~ctools0), I ran a « juju status » and to my dismay I got this :

$ juju status

Please check your credentials or use ‘juju bootstrap’ to create a new environment.

Error details:

no instances found

Using –show log to get a bit more information gave me the following :

$ juju status –show-log

2013-11-28 15:33:05 ERROR juju supercommand.go:282 Unable to connect to environment « maas14″.

Please check your credentials or use ‘juju bootstrap’ to create a new environment.


Error details:

no instances found

Going to the maas server to look at a few log, I found that juju was indeed sending the agent-name to maas :

GET /MAAS/api/1.0/files/97fbdbaa-c727-4f19-8710-dbc6d361e8db-provider-state/ HTTP/1.1″ 200 516 « - » « Go 1.1 package http » – - [28/Nov/2013:16:33:32 +0100] « GET /MAAS/api/1.0/nodes/?agent_name=97fbdbaa-c727-4f19-8710-dbc6d361e8db&id=node-17ad8da0-5361-11e3-bd0a-525400fd96d7&op=list HTTP/1.1″ 200 203 « - » « Go 1.1 package http »

Well, it turns out that after the upgrade of the maas packages, maas will start to honour the agent-name, but since the instances were created without any agent-name, it was no longer able to provide the information.

Raphael Badin who works on the maas team suggested to use the following maas shell commands to fix things up :

$ sudo maas shell

>>> from maasserver.models import Node
>>> # This assumes one wants to update *all* the nodes present in this MAAS.
>>> Node.objects.all().update(agent_name="AGENT_NAME_FROM_JUJU")

Be very careful with such a command if your maas environment is in production as this will change all the nodes present in MAAS.

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For historical reasons, I have been installing my Ubuntu laptop on a fully encrypted disk for years.  Up until now, I needed to use the alternate CD since this was the only possibility to install with full disk encryption.

This is no longer the case.  If you want to use full disk encryption with Quantal Quetzal, you can use the standard installation CD and will be presented with the following options :

You can then select the « Encrypt the new Ubuntu installation for security » option to request full disk encryption. Alternatively, you can elect to use LVM as I did, but this is not a requirement in order to get full disk encryption.

Kudos to the Ubuntu development team for making this option so simple now !

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Recently, I have realized a major difference in how customer support is done on Ubuntu.

As you know, Canonical provides official customer support for Ubuntu both on server and desktop. This is the work I do : provice customer with the best level of support on the Ubuntu distribution.  This is also what I was doing on my previous job, but for the Red Hat Enterprise Linux and SuSE Linux Enterprise Server distributions.

The major difference that I recently realized is that, unlike my previous work with RHEL & SLES, the result of my work is now available to the whole Ubuntu community, not just to the customers that may for our support.

Here is an example. Recently one of our customer identified a bug with vm-builder in a very specific case.  The work that I did on this bug resulted in a patch that I submitted to the developers who accepted its inclusion in the code. In my previous life, this fix would have been made available only to customers paying a subscription to the vendors through their official update or service pack services.

With Ubuntu, through Launchpad and the regular community activity, this fix will become available to the whole community through the standard -updates channel of our public archives.

This is true for the vast majority of the fixes that are provided to our customers. As a matter of fact, the public archives are almost the only channel that we have to provide fixes to our customers, hence making them available to the whole Ubuntu community at the same time.  This is different behavior and something that makes me a bit prouder of the work I’m doing.

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While testing Oneiric on a separate disk, I wanted to get some files off my laptop’s hard drive which is hosting my normal Natty’s install.  Keeping with a previous setup, I had installed my laptop with a fully encrypted hard disk, using the alternate CD, so I needed a procedure to do this manually.

Previously, I had tested booting the Natty LiveCD and, to my enlightened surprise, the Livce CD did see the encrypted HD and proceeded to ask for the passphrase in order to mount it.  But this time, I’m not running off the LiveCD, but from a complete install which is on a separate hard drive.  Since it took me a while to locate the proper procedure, I thought that I would help google a bit so it is not so deep in the pagerank for others next time.  But first, thanks to UbuntuGeek’s article Rescue and encrypted LUKS LVM volume for providing the solution.

Since creating an encrypted Home directory is easily achieved with standard installation methods, there are many references to how to achieve it for encrypted private directory. Dustin Kirkland’s blog is a very good source of information on those topics. But dealing with an encrypted partition requires a different approach. Here it is (at least for an encrypted partition done using the Ubuntu alternate DVD) :

First of all, you need to make sure that lvm2 and cryptsetup packages are installed. If not, go ahead and install them

 # sudo aptitude install cryptsetup lvm2

Then verify if the dm-crypt module is loaded and load it if it is not

 # sudo modprobe dm-crypt

Once this is done, open  the LUKS partition (using your own encrypted partition name) :

 # sudo cryptsetup luksOpen /dev/sda3 crypt1

You should have to provide the passphrase that is used to unlock your crypted partition here.

Once this is done, you must scan for the LVM volume groups :

 # sudo vgscan –mknodes
 # sudo vgchange -ay

There, you should get the name of the volume group that will be needed to mount the encrypted partition (which happens to be configured as an LVM volume). You can now procede to mount your partition (changing {volumegroup} with the name that you collected in the previous command ) :

# sudo mount /dev/{volumegroup}/root /mnt

Your encrypted data should now be available in the /mnt directory :-)

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Live from my phone

The fun of being a geek is to find silly things to do, like to try to blog from an Android phone.

Well, using the power of the open source (wordpress & Android) looks like it will be easier then expected (aside from the virtual keyboard that makes typing a bit tedious).

Kind of nice…


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Remember that day ?

Not that it is very a original post, but it was 20 years ago.

Linus Benedict Torvalds
View profile
More options Aug 26 1991, 8:12 am

Hello everybody out there using minix -

I’m doing a (free) operating system (just a hobby, won’t be big and
professional like gnu) for 386(486) AT clones. This has been brewing
since april, and is starting to get ready. I’d like any feedback on
things people like/dislike in minix, as my OS resembles it somewhat
(same physical layout of the file-system (due to practical reasons)
among other things).

I’ve currently ported bash(1.08) and gcc(1.40), and things seem to work.
This implies that I’ll get something practical within a few months, and
I’d like to know what features most people would want. Any suggestions
are welcome, but I won’t promise I’ll implement them :-)

Linus (torva…

PS. Yes – it’s free of any minix code, and it has a multi-threaded fs.
It is NOT protable (uses 386 task switching etc), and it probably never
will support anything other than AT-harddisks, as that’s all I have :-( .

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Having a linux based distribution as the operating system on my laptop has many advantages.  One of them is to be able to easily run an apache instance and use my laptop as a local webserver.  This has allowed me to run my very own private mediawiki instance on my laptop and to use it as a note keeping engine.  So the landing page on my web browser looks like this :

Two main advantages of this is that, if I intend to publish some of my notes as a public wiki page, there is minimal effort involved in migrating the data to a public Wiki. Otherwise, I can use the search function to find information on a specific topic, see if I have done things on that subject, etc.

It has been a very useful tool to me and I thought I’d share that experience.

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