Name

git-subrepo - Git Submodule Alternative

Synopsis

git subrepo -h    # Help Overview

git subrepo clone <remote-url> [<subdir>]
git subrepo init <subdir>
git subrepo pull <subdir>
git subrepo push <subdir>

git subrepo fetch <subdir>
git subrepo branch <subdir>
git subrepo commit <subdir>
git subrepo config <subdir>

git subrepo status [<subdir>]
git subrepo clean <subdir>

git subrepo help [<command> | --all]
git subrepo version
git subrepo upgrade

Description

This git command "clones" an external git repo into a subdirectory of your repo. Later on, upstream changes can be pulled in, and local changes can be pushed back. Simple.

Benefits

This command is an improvement from git-submodule and git-subtree; two other git commands with similar goals, but various problems.

It assumes there are 3 main roles of people interacting with a repo, and attempts to serve them all well:

owner - The person who authors/owns/maintains a repo.
users - People who are just using/installing the repo.
collaborators - People who commit code to the repo and subrepos.

The git-subrepo command benefits these roles in the following ways:

Simple and intuitive commandline usage (with tab completion).
Users get your repo and all your subrepos just by cloning your repo.
Users do not need to install git-subrepo, ever.
Collaborators do not need to install unless they want to push/pull.
Collaborators know when a subdir is a subrepo (it has a .gitrepo file).
The .gitrepo file never gets pushed back to the subrepo upstream.
Well named branches and remotes are generated for manual operations.
Owners do not deal with the complications of keeping submodules in sync.
Subrepo repositories can contain subrepos themselves.
Branching with subrepos JustWorksâ„¢.
Different branches can have different subrepos in different states, etc.
Moving/renaming/deleting a subrepo subdir JustWorksâ„¢.
You can init an existing subdirectory into a subrepo.
Your git history is kept squeaky clean.
Upstream history (clone/pull) is condensed into a single commit.
Pulls can use a merge, rebase or force strategies.
You can see the subrepo history with git log subrepo/<subdir>/fetch.
Commits pushed back upstream are not condensed (by default).
Trivial to try any subrepo operations and then reset back.
No configuration required.
Does not introduce history that messes up other git commands.
Fixes known rebase failures with git-subtree.

Installation

The best short answer is:

git clone https://github.com/ingydotnet/git-subrepo /path/to/git-subrepo
echo 'source /path/to/git-subrepo/.rc' >> ~/.bashrc

The complete "Installation Instructions" can be found below.

Note: git-subrepo needs a git version (> 2.7) that supports worktree:s.

Commands

All the subrepo commands use names of actual Git commands and try to do operations that are similar to their Git counterparts. They also attempt to give similar output in an attempt to make the subrepo usage intuitive to experienced Git users.

Please note that the commands are not exact equivalents, and do not take all the same arguments. Keep readingâ€¦

git subrepo clone <repository> [<subdir>] [-b <branch>] [-f] [-m <msg>] [--file=<msg file>] [-e] [--method <merge|rebase>]

Add a repository as a subrepo in a subdir of your repository.

This is similar in feel to git clone. You just specify the remote repo url, and optionally a sub-directory and/or branch name. The repo will be fetched and merged into the subdir.

The subrepo history is squashed into a single commit that contains the reference information. This information is also stored in a special file called <subdir>/.gitrepo. The presence of this file indicates that the directory is a subrepo.

All subsequent commands refer to the subrepo by the name of the subdir. From the subdir, all the current information about the subrepo can be obtained.

The --force option will "reclone" (completely replace) an existing subdir.

The --method option will decide how the join process between branches are performed. The default option is merge.

The clone command accepts the --branch= --edit, --file, --force and --message= options.

git subrepo init <subdir> [-r <remote>] [-b <branch>] [--method <merge|rebase>]

Turn an existing subdirectory into a subrepo.

If you want to expose a subdirectory of your project as a published subrepo, this command will do that. It will split out the content of a normal subdirectory into a branch and start tracking it as a subrepo. Afterwards your original repo will look exactly the same except that there will be a <<subdir/.gitrepo >> file.

If you specify the --remote (and optionally the --branch) option, the values will be added to the <subdir>/.gitrepo file. The --remote option is the upstream URL, and the --branch option is the upstream branch to push to. These values will be needed to do a git subrepo push command, but they can be provided later on the push command (and saved to <<subdir/.gitrepo >> if you also specify the --update option).

Note: You will need to create the empty upstream repo and push to it on your own, using git subrepo push <subdir>.

The --method option will decide how the join process between branches are performed. The default option is merge.

The init command accepts the --branch= and --remote= options.

git subrepo pull <subdir>|--all [-M|-R|-f] [-m <msg>] [--file=<msg file>] [-e] [-b <branch>] [-r <remote>] [-u]

Update the subrepo subdir with the latest upstream changes.

The pull command fetches the latest content from the remote branch pointed to by the subrepo's .gitrepo file, and then tries to merge the changes into the corresponding subdir. It does this by making a branch of the local commits to the subdir and then merging or rebasing (see below) it with the fetched upstream content. After the merge, the content of the new branch replaces your subdir, the .gitrepo file is updated and a single 'pull' commit is added to your mainline history.

The pull command will attempt to do the following commands in one go:

git subrepo fetch <subdir>
git subrepo branch <subdir>
git merge/rebase subrepo/<subdir>/fetch subrepo/<subdir>
git subrepo commit <subdir>
# Only needed for a consequential push:
git update-ref refs/subrepo/<subdir>/pull subrepo/<subdir>

In other words, you could do all the above commands yourself, for the same effect. If any of the commands fail, subrepo will stop and tell you to finish this by hand. Generally a failure would be in the merge or rebase part, where conflicts can happen. Since Git has lots of ways to resolve conflicts to your personal tastes, the subrepo command defers to letting you do this by hand.

When pulling new data, the method selected in clone/init is used. This has no effect on the final result of the pull, since it becomes a single commit. But it does affect the resulting subrepo/<subdir> branch, which is often used for a subrepo push command. See 'push' below for more information. If you want to change the method you can use the config command for this.

When you pull you can assume a fast-forward strategy (default) or you can specify a --rebase, --merge or --force strategy. The latter is the same as a clone --force operation, using the current remote and branch.

Like the clone command, pull will squash all the changes (since the last pull or clone) into one commit. This keeps your mainline history nice and clean. You can easily see the subrepo's history with the git log command:

git log refs/subrepo/<subdir>/fetch

The set of commands used above are described in detail below.

The pull command accepts the --all, --branch=, --edit, --file, --force, --message=, --remote= and --update options.

git subrepo push <subdir>|--all [<branch>] [-m msg] [--file=<msg file>] [-r <remote>] [-b <branch>] [-M|-R] [-u] [-f] [-s] [-N]

Push a properly merged subrepo branch back upstream.

This command takes the subrepo branch from a successful pull command and pushes the history back to its designated remote and branch. You can also use the branch command and merge things yourself before pushing if you want to (although that is probably a rare use case).

The push command requires a branch that has been properly merged/rebased with the upstream HEAD (unless the upstream HEAD is empty, which is common when doing a first push after an init). That means the upstream HEAD is one of the commits in the branch.

By default the branch ref refs/subrepo/<subdir>/pull will be pushed, but you can specify a (properly merged) branch to push.

After that, the push command just checks that the branch contains the upstream HEAD and then pushes it upstream.

The --force option will do a force push. Force pushes are typically discouraged. Only use this option if you fully understand it. (The --force option will NOT check for a proper merge. ANY branch will be force pushed!)

The push command accepts the --all, --branch=, --dry-run, --file, --force, --merge, --message, --rebase, --remote=, --squash and --update options.

git subrepo fetch <subdir>|--force --all [-r <remote>] [-b <branch>]

Fetch the remote/upstream content for a subrepo.

It will create a Git reference called subrepo/<subdir>/fetch that points at the same commit as FETCH_HEAD. It will also create a remote called subrepo/<subdir>. These are temporary and you can easily remove them with the subrepo clean command.

The fetch command accepts the --force, --all, --branch= and --remote= options.

git subrepo branch <subdir>|--all [-f] [-F]

Create a branch with local subrepo commits.

Scan the history of the mainline for all the commits that affect the subdir and create a new branch from them called subrepo/<subdir>.

This is useful for doing pull and push commands by hand.

Use the --force option to write over an existing subrepo/<subdir> branch.

The branch command accepts the --all, --fetch and --force options.

git subrepo commit <subdir> [<subrepo-ref>] [-m <msg>] [--file=<msg file>] [-e] [-f] [-F]

Add subrepo branch to current history as a single commit.

This command is generally used after a hand-merge. You have done a subrepobranch and merged (rebased) it with the upstream. This command takes the HEAD of that branch, puts its content into the subrepo subdir and adds a new commit for it to the top of your mainline history.

This command requires that the upstream HEAD be in the subrepo/<subdir> branch history. That way the same branch can push upstream. Use the --force option to commit anyway.

The commit command accepts the --edit, --fetch, --file, --force and --message= options.

git subrepo status [<subdir>|--all|--ALL] [-F] [-q|-v]

Get the status of a subrepo. Uses the --all option by default. If the --quiet flag is used, just print the subrepo names, one per line.

The --verbose option will show all the recent local and upstream commits.

Use --ALL to show the subrepos of the subrepos (ie the "subsubrepos"), if any.

The status command accepts the --all, --ALL, --fetch, --quiet and --verbose options.

git subrepo clean <subdir>|--all|--ALL [-f]

Remove artifacts created by fetch and branch commands.

The fetch and branch operations (and other commands that call them) create temporary things like refs, branches and remotes. This command removes all those things.

Use --force to remove refs. Refs are not removed by default because they are sometimes needed between commands.

Use --all to clean up after all the current subrepos. Sometimes you might change to a branch where a subrepo doesn't exist, and then --all won't find it. Use --ALL to remove any artifacts that were ever created by subrepo.

To remove ALL subrepo artifacts:

git subrepo clean --ALL --force

The clean command accepts the --all, --ALL, and --force options.

git subrepo config <subdir> <option> [<value>] [-f]

Read or update configuration values in the subdir/.gitrepo file.

Because most of the values stored in the .gitrepo file are generated you will need to use --force if you want to change anything else then the method option.

Example to update the method option for a subrepo:

git subrepo config foo method rebase

git subrepo help [<command>|--all]

Same as git help subrepo. Will launch the manpage. For the shorter usage, use git subrepo -h.

Use git subrepo help <command> to get help for a specific command. Use --all to get a summary of all commands.

The help command accepts the --all option.

git subrepo version [-q|-v]

This command will display version information about git-subrepo and its environment. For just the version number, use git subrepo --version. Use --verbose for more version info, and --quiet for less.

The version command accepts the --quiet and --verbose options.

git subrepo upgrade

Upgrade the git-subrepo software itself. This simply does a git pull on the git repository that the code is running from. It only works if you are on the master branch. It won't work if you installed git-subrepo using make install; in that case you'll need to make install from the latest code.

Command Options

-h

Show a brief view of the commands and options.

--help

Gives an overview of the help options available for the subrepo command.

--version

Print the git-subrepo version. Just the version number. Try the version command for more version info.

--all (-a)

If you have multiple subrepos, issue the command to all of them (if applicable).

--ALL (-A)

If you have subrepos that also have subrepos themselves, issue the command to ALL of them. Note that the --ALL option only works for a subset of the commands that --all works for.

--branch=<branch-name> (-b <branch-name>)

Use a different upstream branch-name than the remote HEAD or the one saved in .gitrepo locally.

--dry-run (-N)

For the push command, do everything up until the push and then print out the actual git push command needed to finish the operation.

--edit (-e)

Edit the commit message before committing.

--fetch (-F)

Use this option to fetch the upstream commits, before running the command.

--file=<commit msg file>

Supply your own commit message from a file

--force (-f)

Use this option to force certain commands that fail in the general case.

NOTE: The --force option means different things for different commands. Read the command specific doc for the exact meaning.

--merge (-M)

Use a merge strategy to include upstream subrepo commits on a pull (or setup for push).

--message=<message> (-m <message>)

Specify your own commit message on the command line.

--rebase (-R)

Use a rebase strategy to include upstream subrepo commits on a pull (or setup for push).

--remote=<remote-url> (-r <remote-url>)

Use a different remote-url than the one saved in .gitrepo locally.

--squash (-s)

Squash all commits on a push into one new commit.

--update (-u)

If --branch or --remote are used, and the command updates the .gitrepo file, include these values to the update.

Output Options

--quiet (-q): Print as little info as possible. Applicable to most commands.
--verbose (-v): Print more information about the command execution and results. Applicable to most commands.
--debug (-d): Show the actual git (and other) commands being executed under the hood. Applicable to most commands.
--DEBUG (-x): Use the Bash set -x option which prints every command before it is run. VERY noisy, but extremely useful in deep debugging. Applicable to all commands.

Environment Variables

The git-subrepo command exports and honors some environment variables:

GIT_SUBREPO_ROOT: This is set by the .rc file, if you use that method to install / enable git-subrepo. It contains the path of the git-subrepo repository.
GIT_SUBREPO_RUNNING: This variable is exported when git-subrepo is running. It is set to the pid of the git-subrepo process that is running. Other processes, like git hooks for instance, can use this information to adjust accordingly.
GIT_SUBREPO_COMMAND: This variable is exported when git-subrepo is running. It is set to the name of the git-subrepo subcommand that is running.
GIT_SUBREPO_PAGER: Use this to specify the pager to use for long output commands. Defaults to $PAGER or less.
GIT_SUBREPO_QUIET: Set this for quiet (-q) output.
GIT_SUBREPO_VERBOSE: Set this for verbose (-v) output.
GIT_SUBREPO_DEBUG: Set this for debugging (-d) output.

Installation Instructions

There are currently 3 ways to install git-subrepo. For all of them you need to get the source code from GitHub:

git clone https://github.com/ingydotnet/git-subrepo /path/to/git-subrepo

The first installation method is preferred: source the .rc file. Just add a line like this one to your shell startup script:

source /path/to/git-subrepo/.rc

That will modify your PATH and MANPATH, and also enable command completion.

The second method is to do these things by hand. This might afford you more control of your shell environment. Simply add the lib and man directories to your PATH and MANPATH:

export GIT_SUBREPO_ROOT="/path/to/git-subrepo"
export PATH="/path/to/git-subrepo/lib:$PATH"
export MANPATH="/path/to/git-subrepo/man:$MANPATH"

See below for info on how to turn on Command Completion.

The third method is a standard system install, which puts git-subrepo next to your other git commands:

make install        # Possibly with 'sudo'

This method does not account for upgrading and command completion yet.

Windows

This command is known to work in these Windows environments:

Git for Windows -- https://git-for-windows.github.io/
Babun -- http://babun.github.io/
Cygwin -- https://www.cygwin.com/

Let us know if there are others that it works (or doesn't work) in.

Testing

The git-subrepo repository comes with a extensive test suite. You can run it with:

make test

or if you don't have make on your system:

prove -v test

Upgrading

If you used the .rc or PATH method of installation, just run this to upgrade git-subrepo:

git subrepo upgrade

Or (same thing):

cd /path/to/git-subrepo
git pull

If you used make install method, then run this again (after git pull):

make install        # Possibly with 'sudo'

Command Completion

The git subrepo command supports <TAB>-based command completion. If you don't use the .rc script (see Installation, above), you'll need to enable this manually to use it.

In Bash

If your Bash setup does not already provide command completion for Git, you'll need to enable that first:

source <Git completion script>

On your system, the Git completion script might be found at any of the following locations (or somewhere else that we don't know about):

/etc/bash_completion.d/git
/usr/share/bash-completion/git
/usr/share/bash-completion/completions/git
/opt/local/share/bash-completion/completions/git
/usr/local/etc/bash_completion.d/git
~/.homebrew/etc/bash_completion.d/git

In case you can't find any of these, this repository contains a copy of the Git completion script:

source /path/to/git-subrepo/share/git-completion.bash

Once Git completion is enabled (whether you needed to do that manually or not), you can turn on git-subrepo completion with a command like this:

source /path/to/git-subrepo/share/completion.bash

In zsh

In the Z shell (zsh), you can manually enable git-subrepo completion by adding the following line to your ~/.zshrc, before the compinit function is called:

fpath=('/path/to/git-subrepo/share/zsh-completion' $fpath)

Status

The git-subrepo command has been used in production and seems to get the job done. Development is still ongoing but mostly just for fixing bugs.

Trying subrepo out is simple and painless (this is not git submodule). Nothing is permanent (if you do not push to shared remotes). ie You can always play around and reset back to the beginning without pain.

This command has a test suite (run make test), but surely has many bugs. If you have expertise with Git and subcommands, please review the code, and file issues on anything that seems wrong.

If you want to chat about the git-subrepo command, join #gitcommands on irc.freenode.net.

Notes

Works on POSIX systems: Linux, BSD, OSX, etc.
Works on various Windows environments. See "Windows" section above.
The git-subrepo repo itself has 2 subrepos under the ext/ subdirectory.
Written in (very modern) Bash, with full test suite. Take a look.
A .gitrepo file never is in the top level dir (next to a .git/ dir).

Working with nested subrepos

git-subrepo supports adding subrepos which themselves make use of subrepos. In fact, subrepo itself is built this way. Take a look in the ext/ folder, it houses 2 dependencies as subrepos, test-more-bash and bashplus.

test-more-bash itself depends on 2 more subrepos: bashplus again, and test-tap-bash.

The structure is therefore as follows:

git-subrepo
  |- bashplus
  |- test-more-bash
    |- bashplus
    |- test-tap-bash

However, it's important to understand how this works. Here's the key idea: There is no special handling for nested subrepos.

When you clone a subrepo, all git-subrepo does is download the code and set up the subrepo file. This means that all the subrepo commands simply act on the subrepo as a whole, treating nested subrepos like any other part of the source code.

Let's look at what this means in practice. Say you have a structure as follows:

app-foo
  |- barlib
     |- bazlib

You're working on app-foo, and make some changes to bazlib. How should you upstream these changes?

From the perspective of app-foo, you've simply made some changes to barlib. Whether or not those changes were themselves in a subrepo is irrelevant. So, just like any other changes, you run

git subrepo push barlib

Now, if barlib is a library you don't maintain, your responsibility would end here. barlib's maintainer would see your changes and decide what to do with them.

If you do maintain barlib, you might now want to upstream the changes all the way into bazlib. You could be tempted to try running something like:

git subrepo push barlib/bazlib

but you'll soon find out that doesn't work. app-foo doesn't know anything about the link between barlib and bazlib.

What you should do is treat the changes to barlib as if they would come from another contributor, aka:

go to a local copy of barlib
pull down the changes with git pull
you notice the changes include some work on your subrepo, time to upstream them: git subrepo push bazlib

And you're done! One final step you'll likely want to do is to go back to app-foo and run git subrepo pull barlib, because the push you just did added a new commit.

Authors

Ingy döt Net <ingy@ingy.net>
Magnus Carlsson <grimmymail@gmail.com>
Austin Morgan <admorgan@morgancomputers.net>

License and Copyright

The MIT License (MIT)

Copyright (c) 2013-2024 Ingy döt Net

License

yinghai/git-subrepo

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