Monorepo notes

Generating

Use the create_monorepo script to regenerate from current master(s).

Structure

This is a result of Git merge of several unrelated histories, each of which is moved to its own subdirectory during the merge.

That means that this is actually all the original repos at the same time. You can check out any historical commit hash, or any historical tag.

All tags from the previous history still exist, and in addition, each has a version named by its directory. I.e., for trezor-mcu tag v1.6.3, you can also check out legacy/v1.6.3.

Merging pre-existing branches

Because the repository shares all the histories, merging a branch or PR can be done with a simple git merge. It's often necessary to add hints to git by specifying a merge strategy - especially when some commits add new files.

Use the following options: -s subtree -X subtree=<destdir>.

Example for your local checkout:

$ git remote add core-local ~/git/trezor-core
$ git fetch core-local
$ git merge core-local/wip -s subtree -X subtree=core

Same options should be used for git rebase of a pre-existing branch.

Sub-repositories

The monorepo has two subdirectories that can be exported to separate repos:

  • common exports to https://github.com/trezor/trezor-common
  • crypto exports to https://github.com/trezor/trezor-crypto

These exports are managed with git-subrepo tool. To export all commits that touch one of these directories, run the following command:

$ git subrepo push <dirname>

You will need commit access to the respective GitHub repository.

For installation instructions and detailed usage info, refer to the git-subrepo README.

Sketch of further details:

What git-subrepo does under the hood is create and fetch a remote for the export, check out parent revision and replay all commits since commit using something along the lines of git filter-branch --subdirectory-filter.

So basically a nicely tuned git-subtree.

This can all be done manually if need be (or if you need more advanced usecases like importing changes from the repo commit-by-commit, because git-subrepo will squash on import). See this nice article for hints.