GIT_STRATEGY no-checkout

Description

I often find myself running git merge at the beginning of a build script. Also, I often find myself using just a few files from a repository, for example docker-compose.yml for a deploy from pre-built images. I feel it's a waste to check out all files of the repository in those cases.

Proposal

Add a GIT_STRATEGY no-checkout that skips the git checkout part.

It seems that git clone --no-checkout and git checkout are already separate operations. Adding this GIT_STRATEGY would then allow users to do all git operations themselves in the build script.

This is a useful idea, but I'm not sure GIT_STRATEGY is the right place for it. Checkout is run for both GIT_STRATEGY=clone and GIT_STRATEGY=fetch, so we end up with four possibilities rather than three.

We could easily add another variable to configure this, though. Wdyt @tmaczukin ?

added improvement label

@nick.thomas I agree, the idea is interesting, but it should be implemented as a separate variable. I'd propose GIT_CHECKOUT=(true|false) and implement it similar to GIT_STRATEGY, so a method in common/build.go and an if statement at the beginning of writeCheckoutCmd method in shell/abstract.go.

changed milestone to %v1.10

added ~1009246 label

How is this different than GIT_STRATEGY: none? https://docs.gitlab.com/ce/ci/yaml/#git-strategy

@markpundsack With GIT_STRATEGY: none we're doing nothing. With GIT_STRATEGY: clone we're doing two steps: clone and checkout. With GIT_STRATEGY: fetch we're doing also two steps: fetch (with a fallback to clone if directory is empty) and checkout.

For both strategies we're doing a clone/fetch without checkout, and then we're doing a checkout for a particular reference provided in build data. This proposal is about leaving strategies as they exists now (so none, clone or fetch) but add ability to skip the checkout step. Then you could do something like:

variables:
  GIT_STRATEGY: clone
  GIT_CHECKOUT: false
script:
  - git checkout master
  - git merge $CI_BUILD_REF_NAME
  - ...

You could still do this with current workflow, but this would provide an option to skip one step, that is not needed by the user. And of course it would be true by default :)

changed milestone to %v1.11

added To Do label

assigned to @cpallares

changed milestone to %Backlog

mentioned in merge request !585 (merged)

changed milestone to %9.3

closed via merge request !585 (merged)