Code import in depth

Launchpad has the ability to constantly sync code from external repositories by setting up a code import. This is a one-way sync, from the external source to Launchpad.

Design decisions

Code import / code mirroring is not triggered by the remote repository, but it is rather triggered from the Launchpad side several times a day. This should be fine for most use cases.

The benefit of doing it this way is there is no need to install a webhook on the remote repository to trigger an import or update of the repository.


While the current implementation has some support for setting it on a per-import basis, that’s actually not exposed right now.

The frequency depends on the type of the revision control system, and is set in effective_update_interval, see the codeimport module.

As the default intervals in the config schema aren’t overridden anywhere right now, you can look them up in the codeimport section in the configuration schema.

Trigger code import

On a high level, each import has a database field, which indicates when the next import should be performed. We could think of this as task queue.

A scheduler queries the database, and in case there are jobs, a worker will pick one up.

Let’s have a look in detail.

After the import job runs, and if the import is still in the REVIEWED state, i.e. it hasn’t failed too many times, or it hasn’t been suspended or similar, it then schedules a new job, that is, it sets a new date in the date_due column.

Depending on the work load, there is no guarantee that a job will be picked up in time, as the process works like this:

  • cronjobs in lp-codeimport run workers

  • when the code import worker is looking for work to do, it calls getJobForMachine in the codeimportscheduler module

  • that calls getJobForMachine in the codeimport module which makes a DB query to fetch the first job from a table that has due_date not in the future, and that is marked as pending

  • it then triggers the import


The short answer is that we currently aim for every 12 hours for code imports from CVS (very few nowadays), and every 6 hours from all other revision control systems.