Thunderbird Cross-channel

Thunderbird is localized with “cross-channel”, a process developed for Firefox to keep all localized strings in a single repository for all release channels.

The Firefox Cross Channel documentation is a good reference, and this document will only discuss the differences for Thunderbird.

comm-l10n and comm-strings-quarantine

Firefox has “gecko-strings”. Thunderbird has comm-l10n.

Firefox has “gecko-strings-quarantine”. Thunderbird has comm-strings-quarantine.

The cron job that updates comm-strings-quarantine runs on comm-central and uses the same script as Firefox, with a slightly different configuration.

quarantine-to-strings

After the string review, comm-l10n is updated with the latest commits to comm-strings-quarantine. This is handled by a mach command, run twice:

mach tb-l10n-quarantine-to-strings --quarantine-path quarantine --comm-l10n-path comm-l10n clean prep migrate
mach tb-l10n-quarantine-to-strings --quarantine-path quarantine --comm-l10n-path comm-l10n push

As the quarantine repo does not have subdirectories for each locale, some Mercurial magic is used to handle the path rewriting.

The last converted revision of comm-strings-quarantine is saved in an extra metadata field in comm-l10n by hg convert. That revision’s first child is the next one to convert. A splicemap is written to splice it onto the tip of comm-l10n. A filemap file is also used to rewrite the paths into en-US.

The resulting hg convert command looks like:

hg convert \
  --config convert.hg.saverev=True \
  --config convert.hg.sourcename=comm-strings-quarantine \
  --config convert.hg.revs=5ee85b7de10c0acb3281d2fa4ade3104833f313d:tip \
  --filemap /tmp/filemaps5axhbzd.txt \
  --splicemap /tmp/splicemaprr2tqrk2.txt \
  --datesort \
  /tmp/quarantine \
  /tmp/comm-l10n

Using Mercurial’s extra metadata fields to save the commit information allows for maintaining state information without needing a separate metadata file stored somewhere.

Monorepo

comm-l10n is a monorepo that includes the source (en-US) strings as well as the target languages.

L10n Repackaging during Release Promotion

As Thunderbird uses strings from Gecko Toolkit, it’s necessary to pull those strings from l10n-central and combine them with comm-l10n to produce a localized build.

In automation, this is done in two steps. A l10n-pre job gets all of the strings from all locales from the l10n-central repositories and comm-l10n and produces a tar file, strings_all.tar.xz. The L10n repackage jobs use that file rather than cloning from l10n-central. strings_all.tar.xz is also uploaded to the FTP archive along with the source code tar file for use by downstream packagers.

For local development, mach build installers-$AB_CD and ./mach build langpack-$AB_CD will do the same combining of string sources as above in one step.

In both cases, the comm-l10n changset used is the one in comm/mail/locales/l10n-changesets.json and the l10n-central revisions are taken from browser/locales/l10n-changesets.json.