On Thu, May 07, 2020 at 08:17:27AM -0400, Jeff King wrote:
> > But doesn't this (i.e. uses: actions/github-script) still pay the
> > cost of spinning up a VM? How expensive is it to check out a small
> > tree with a single file, whether it is ref-whitelist or allow-ref?
>
> I suspect this script mechanism may be much cheaper. I don't know the
> implementation details, but spinning up a nodejs container to run a
> javascript snippet should be much cheaper than a full ubuntu VM running
> "git clone" (the clone itself should be super cheap because it's a
> shallow single-branch clone of a tree with one file in it, but getting
> there is relatively heavy-weight).
Sorry, this is all complete nonsense. There is no magical nodejs
container in Actions. You still have to say "runs-on: ubuntu-latest". So
it's still spinning up that VM and then running inside there.
I just did a timing with three jobs:
noop:
runs-on: ubuntu-latest
steps:
- run: exit 0
script:
runs-on: ubuntu-latest
steps:
- uses: actions/github-script@0.9.0
with:
script: |
const req = {
owner: context.repo.owner,
repo: context.repo.repo,
ref: "refs/ci/config"
};
try {
req.tree_sha = (await github.git.getRef(req)).data.object.sha;
(await github.git.getTree(req))
.tree.filter(e => e.path == 'ref-whitelist').map(e => {
req.file_sha = e.sha;
});
const list = Buffer.from((await github.git.getBlob(req)).data.content, 'base64').toString('UTF-8');
core.setOutput('enabled', `\n${list}`.indexOf(`\n${{github.ref}}\n`) < 0 ? 'no' : 'yes');
} catch (e) {
core.setOutput('enabled', 'yes');
}
checkout:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
continue-on-error: true
with:
ref: refs/ci/config
- run: ./allow-ref ${{ github.ref }}
and they took 1, 2, and 3 seconds respectively. They spend 2s getting
the environment set up and the actions loaded. So the API one spent less
than 1s on the network, but the single-file checkout spent slightly
more. Given the timing variations I've seen, I wouldn't be surprised if
it sometimes goes the other way. But even if those numbers are accurate,
I don't think the cost difference is enough to force our hand either
way.
-Peff
