Canonical Voices

Posts tagged with 'tip'

Martin Pool

Short story: http://pad.lv/12345 takes you to bug 12345, and pad.lv describes more abbreviations.

padlv

Sometimes you’d like to point people to an interesting bug in a project that uses Launchpad, like bug 685380 (that ‘1′ and ‘l’ may need to be more distinct in the new Ubuntu Font).

Typing out https://launchpad.net/bugs/685380 is a bit tedious, and it uses up a fair bit of space in a microblog entry. You can use any of innumerable URL-shortening services, but then the URL’s opaque; which is a shame since it really just wants to represent a 6-digit number.

Therefore: pad.lv (pad love), transparent short URLs for bugs, and other things including projects, people, bug-filing forms, packages, and more.

Maybe someone would like to make bookmarklets that generate these links, or add them into the Launchpad UI?

Thanks to Latvia for letting us use a fraction of their domain name space!

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Martin Pool

You may start getting “Failed to fetch” error messages when updating your software sources (e.g. through “apt-get update” or “Reload package information” in Synaptic), which may be due to a bug we’ve just cleaned up in Launchpad’s PPAs.

The error looks like this:

  W: Failed to fetch http://ppa.launchpad.net/chromium-daily/ppa/ubuntu/dists/maverick/Release
  Unable to find expected entry  restricted/binary-i386/Packages in Meta-index file (malformed Release file?)

  E: Some index files failed to download, they have been ignored, or old ones used instead.

Fixing the cause of the error

Here’s how to fix it. In your terminal, type:

 sudo gedit /etc/apt/sources.list

In the editor, look for PPA sources — these are URLs that feature the ppa.launchpad.net domain. In this example, someone has set up the ~ubuntu-x-swat/x-updates PPA incorrectly:

 deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu maverick main
 deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu maverick restricted
 deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu maverick universe
 deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu maverick multiverse

All of these refer to different components within the same PPA. PPAs only have the first component, so you should delete lines for PPAs that don’t end in “main”. Watch out for lines that wrap, as with the “restricted”, “universe” and “multiverse” examples above.

You may also need to check source lists under the /etc/apt/sources.list.d directory.

Note: you should leave your standard Ubuntu sources, and any non-PPA sources, just as they are.

If you’re not sure how to do this, pop into #launchpad on freenode and one of the Launchpad community will help.

Why this has happened

The Debian-style archives used by Ubuntu are often divided into different components. With Ubuntu, you’ve probably heard of at least “main” and “universe”.

PPAs don’t use these components. However, a bug in Launchpad meant that, until December, PPAs were published with a number of different components. All of these components were empty and there was no way to publish anything to them.

Today, we started to remove these empty components from PPAs. The only impact we anticipate is that anyone whose sources.list referenced these components in a PPA will now see an error when performing an apt-get update or similar.

No packages are being deleted and anyone with a correctly defined sources.list will be able to carry on just as before.

(Originally from Julian.)

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Martin Pool

Three tips from Leonard’s lightning talk in Prague about writing faster Launchpadlib API clients:

1. Use the latest launchpadlib. It gets faster from one release to the next. (The versions in the current Ubuntu release should be fine; otherwise run from the branch or the latest tarball.)

2. Profile:

    import httplib2
    httplib2.debuglevel = 1

will show each http request and response, so that you can see what’s taking time.

3. Fetch objects only once:

Don’t do this:

    if bug.person is not None:
        print bug.person.name

instead

    p = bug.person
    if p is not None:
        print p.name

In the first case, the client may fetch the Person object twice. (We may fix this in future.)

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