sync: Implement fetchcmd for standard Git layouts

Introduce support for `repo.fetchcmd` configuration, allowing users to
specify a custom command to fetch project data instead of
`_RemoteFetch`.

When `repo.fetchcmd` is specified, `repo` will execute it instead of
`_RemoteFetch` during the network half of sync. Note that
`repo.fetchcmd` requires `repo.uselocalgitdirs` to be enabled.

The command is executed in a subshell with project-context environment
variables, including the new `REPO_TREV` (target revision resolved to a
commit hash) and `REPO_PROJECT_FETCH_URL`.

After execution, `repo` verifies that the target commit is available and
that the tracking ref and FETCH_HEAD are correctly updated.

Tested with:
```
> ~/git-repo/repo init -u https://android-review.googlesource.com/platform/manifest \
    --repo-url file:///usr/local/google/home/gavinmak/git-repo \
    --groups developers \
    --no-repo-verify \
    --use-local-gitdirs
...

> git config --file .repo/manifests.git/config repo.fetchcmd 'mkdir -p $REPO_PATH && cd $REPO_PATH && if [ ! -d .git ]; then git init && git remote add aosp $REPO_PROJECT_FETCH_URL; fi && git fetch aosp $REPO_TREV && git reset --hard $REPO_TREV && mkdir -p .git/refs/remotes/aosp && echo $REPO_TREV > .git/refs/remotes/aosp/main && echo $REPO_TREV > .git/FETCH_HEAD'

> ~/git-repo/repo sync -j32
warning: repo is not tracking a remote branch, so it will not receive updates; run `repo init --repo-rev=stable` to fix.
You are currently enrolled in Git submodules experiment (go/android-submodules-quickstart).  Use --no-use-superproject to override.

Syncing: 100% (4/4), done in 1m15.686s
Finalizing sync state...
repo sync has finished successfully.
```

Bug: 513329573
Change-Id: I754d3f3c78e86fdeee1a72115297a75b571bc497
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/583883
Reviewed-by: Becky Siegel <beckysiegel@google.com>
Tested-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
3 files changed
tree: 7f1f0792f9435263a4e85a7effd97834164de32d
  1. .github/
  2. agents/
  3. docs/
  4. hooks/
  5. man/
  6. release/
  7. subcmds/
  8. tests/
  9. .flake8
  10. .gitattributes
  11. .gitignore
  12. .gitreview
  13. .mailmap
  14. .project
  15. .pydevproject
  16. cipd_manifest.txt
  17. cipd_manifest.versions
  18. color.py
  19. command.py
  20. completion.bash
  21. completion.zsh
  22. constraints.txt
  23. CONTRIBUTING.md
  24. editor.py
  25. error.py
  26. event_log.py
  27. fetch.py
  28. git_command.py
  29. git_config.py
  30. git_refs.py
  31. git_ssh
  32. git_superproject.py
  33. git_trace2_event_log.py
  34. git_trace2_event_log_base.py
  35. hooks.py
  36. LICENSE
  37. main.py
  38. MANIFEST.in
  39. manifest_xml.py
  40. pager.py
  41. platform_utils.py
  42. platform_utils_win32.py
  43. progress.py
  44. project.py
  45. pyproject.toml
  46. README.md
  47. repo
  48. repo_logging.py
  49. repo_trace.py
  50. requirements.json
  51. run_tests
  52. run_tests.vpython3
  53. run_tests.vpython3.8
  54. setup.py
  55. ssh.py
  56. wrapper.py
README.md

repo

Repo is a tool built on top of Git. Repo helps manage many Git repositories, does the uploads to revision control systems, and automates parts of the development workflow. Repo is not meant to replace Git, only to make it easier to work with Git. The repo command is an executable Python script that you can put anywhere in your path.

Contact

Please use the repo-discuss mailing list or issue tracker for questions.

You can file a new bug report under the “repo” component.

Please do not e-mail individual developers for support. They do not have the bandwidth for it, and often times questions have already been asked on repo-discuss or bugs posted to the issue tracker. So please search those sites first.

Install

Many distros include repo, so you might be able to install from there.

# Debian/Ubuntu.
$ sudo apt-get install repo

# Gentoo.
$ sudo emerge dev-vcs/repo

You can install it manually as well as it's a single script.

$ mkdir -p ~/.bin
$ PATH="${HOME}/.bin:${PATH}"
$ curl https://storage.googleapis.com/git-repo-downloads/repo > ~/.bin/repo
$ chmod a+rx ~/.bin/repo

Shell Completion

Repo includes completion scripts for Bash and Zsh.

Bash

To enable completion in Bash, source completion.bash in your ~/.bashrc:

source /path/to/git-repo/completion.bash

Zsh

To enable completion in Zsh, you can either:

  1. Copy or symlink completion.zsh to a file named _repo in a directory in your $fpath:

    mkdir -p ~/.zsh/completion
    # You can copy the file:
    cp /path/to/git-repo/completion.zsh ~/.zsh/completion/_repo
    # Or symlink it:
    ln -s /path/to/git-repo/completion.zsh ~/.zsh/completion/_repo
    

    Then add that directory to your fpath in ~/.zshrc before compinit:

    fpath=(~/.zsh/completion $fpath)
    autoload -Uz compinit
    compinit
    
  2. Or source the file directly and call compdef in your ~/.zshrc:

    source /path/to/git-repo/completion.zsh
    compdef _repo repo