added submodule support

[japettyjohn]

Added option to init and update submodules. If depth is specified it uses shallow submodules.

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[k8s-reviewable]

This change is 

[thockin]

I don't see anything wrong with this, but I don't know submodules well. Can you add a set of cases to the test_e2e.sh to demonstrate this?

[thockin]

also, you need to sign the CLA :)

[stp-ip]

From a submodule perspective it looks good. Waiting for some test cases and the CLA.

[abh]

FWIW this is working well for me -- I made a build at quay.io/abh/git-sync:v2.0.5-submodule

[japettyjohn]

@abh That's great to hear. I've been running with success as well for some months, I haven't gotten around to implementing shallow checkouts though which would help a lot for large/ancient dependencies and make it consistent with the top level checkout features.

[thockin]

Sorry for letting this languish. It looks overall ok, but it needs an e2e test, please?

[thockin]

should the flag be "submodules" ?

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[abh]

@japettyjohn any chance of resurrecting this so it can be merged? :-)

[StephenWithPH]

@abh ... I'd like to hear more about how it's working for you.

Background: I took a stab at adding E2E tests to cover @japettyjohn 's work. The code works as expected in the repo itself, but it does not work down the symlinked-path. My tests are failing, since I'm expecting the submodule in the symlinked path.

As I understand it, the symlinked path is what is supposed to matter; from the docs:

When it re-pulls, it updates the destination directory atomically. In order to do this, it uses a git worktree in a subdirectory of the --root and flips a symlink

In the tree below, ottherrepo is submoduled inside of repo. The code runs and does pull it down (main.go:465] run("/tmp/git-sync-test.14210/root/rev-e9fc17a57997bad70aafe925b73054100ef61878"): git submodule update --init), but none of this makes it to the worktree where it counts (main.go:465] run("/tmp/git-sync-test.14210/root"): git worktree add /tmp/git-sync-test.14210/root/rev-e9fc17a57997bad70aafe925b73054100ef61878 origin/master).

git-sync-test.14210 $ tree
.
├── log.branch-sync
├── log.cross-branch-tag-sync
├── log.default-sync
├── log.head-once
├── log.head-sync
├── log.rev-once
├── log.rev-sync
├── log.submodule
├── log.tag-sync
├── otherrepo
│   └── otherfile
├── repo
│   ├── file
│   └── otherrepo
│       └── otherfile
└── root
    ├── repo -> rev-e9fc17a57997bad70aafe925b73054100ef61878
    └── rev-e9fc17a57997bad70aafe925b73054100ef61878
        └── file

https://git-scm.com/docs/git-worktree tells me that:

BUGS
Multiple checkout in general is still experimental, and the support for submodules is incomplete. It is NOT recommended to make multiple checkouts of a superproject.