nixpkgs/.github/workflows/labels.yml

# WARNING:
# When extending this action, be aware that $GITHUB_TOKEN allows some write
# access to the GitHub API. This means that it should not evaluate user input in
# a way that allows code injection.

name: "Label PR"

on:
  schedule:
    - cron: '07,17,27,37,47,57 * * * *'
  workflow_call:
  workflow_dispatch:
    inputs:
      updatedWithin:
        description: 'Updated within [hours]'
        type: number
        required: false
        default: 0 # everything since last run

concurrency:
  # This explicitly avoids using `run_id` for the concurrency key to make sure that only
  # *one* non-PR run can run at a time.
  group: labels-${{ github.workflow }}-${{ github.event_name }}-${{ github.event.pull_request.number }}
  # PR- and manually-triggered runs will be cancelled, but scheduled runs will be queued.
  cancel-in-progress: ${{ github.event_name != 'schedule' }}

permissions:
  issues: write # needed to create *new* labels
  pull-requests: write

defaults:
  run:
    shell: bash

jobs:
  labels:
    name: label-pr
    runs-on: ubuntu-24.04-arm
    if: github.event_name != 'schedule' || github.repository_owner == 'NixOS'
    steps:
      - name: Install dependencies
        run: npm install @actions/artifact

      - name: Labels from API data and Eval results
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
        env:
          UPDATED_WITHIN: ${{ inputs.updatedWithin }}
        with:
          script: |
            const path = require('node:path')
            const { DefaultArtifactClient } = require('@actions/artifact')
            const { readFile } = require('node:fs/promises')

            const artifactClient = new DefaultArtifactClient()

            if (process.env.UPDATED_WITHIN && !/^\d+$/.test(process.env.UPDATED_WITHIN))
              throw new Error('Please enter "updated within" as integer in hours.')

            const cutoff = new Date(await (async () => {
              // Always run for Pull Request triggers, no cutoff since there will be a single
              // response only anyway. 0 is the Unix epoch, so always smaller.
              if (context.payload.pull_request?.number) return 0

              // Manually triggered via UI when updatedWithin is set. Will fallthrough to the last
              // option if the updatedWithin parameter is set to 0, which is the default.
              const updatedWithin = Number.parseInt(process.env.UPDATED_WITHIN, 10)
              if (updatedWithin) return new Date().getTime() - updatedWithin * 60 * 60 * 1000

              // Normally a scheduled run, but could be workflow_dispatch, see above. Go back as far
              // as the last successful run of this workflow to make sure we are not leaving anyone
              // behind on GHA failures.
              // Defaults to go back 1 hour on the first run.
              return (await github.rest.actions.listWorkflowRuns({
                ...context.repo,
                workflow_id: 'labels.yml',
                event: 'schedule',
                status: 'success',
                exclude_pull_requests: true
              })).data.workflow_runs[0]?.created_at ?? new Date().getTime() - 1 * 60 * 60 * 1000
            })())
            core.info('cutoff timestamp: ' + cutoff.toISOString())

            // To simplify this action's logic we fetch the pull_request data again below, even if
            // we are already in a pull_request event's context and would have the data readily
            // available. We do this by filtering the list of pull requests with head and base
            // branch - there can only be a single open Pull Request for any such combination.
            const prEventCondition = !context.payload.pull_request ? undefined : {
              // "label" is in the format of `user:branch` or `org:branch`
              head: context.payload.pull_request.head.label,
              base: context.payload.pull_request.base.ref
            }

            await github.paginate(
              github.rest.pulls.list,
              {
                ...context.repo,
                state: 'open',
                sort: 'updated',
                direction: 'desc',
                ...prEventCondition
              },
              async (response, done) => (await Promise.allSettled(response.data.map(async (pull_request) => {
                try {
                  const log = (k,v) => core.info(`PR #${pull_request.number} - ${k}: ${v}`)

                  log('Last updated at', pull_request.updated_at)
                  if (new Date(pull_request.updated_at) < cutoff) return done()
                  log('URL', pull_request.html_url)

                  const run_id = (await github.rest.actions.listWorkflowRuns({
                    ...context.repo,
                    workflow_id: 'eval.yml',
                    event: 'pull_request_target',
                    // For PR events, the workflow run is still in progress with this job itself.
                    status: prEventCondition ? 'in_progress' : 'success',
                    exclude_pull_requests: true,
                    head_sha: pull_request.head.sha
                  })).data.workflow_runs[0]?.id

                  // Newer PRs might not have run Eval to completion, yet. We can skip them, because this
                  // job will be run as part of that Eval run anyway.
                  log('Last eval run', run_id ?? '<pending>')
                  if (!run_id) return;

                  const artifact = (await github.rest.actions.listWorkflowRunArtifacts({
                    ...context.repo,
                    run_id,
                    name: 'comparison'
                  })).data.artifacts[0]

                  // Instead of checking the boolean artifact.expired, we will give us a minute to
                  // actually download the artifact in the next step and avoid that race condition.
                  // Older PRs, where the workflow run was already eval.yml, but the artifact was not
                  // called "comparison", yet, will be skipped as well.
                  log('Artifact expires at', artifact?.expires_at ?? '<not found>')
                  if (new Date(artifact?.expires_at ?? 0) < new Date(new Date().getTime() + 60 * 1000)) return;

                  await artifactClient.downloadArtifact(artifact.id, {
                    findBy: {
                      repositoryName: context.repo.repo,
                      repositoryOwner: context.repo.owner,
                      token: core.getInput('github-token')
                    },
                    path: path.resolve(pull_request.number.toString()),
                    expectedHash: artifact.digest
                  })

                  // Get all currently set labels that we manage
                  const before =
                    pull_request.labels.map(({ name }) => name)
                    .filter(name =>
                      name.startsWith('10.rebuild') ||
                      name == '11.by: package-maintainer' ||
                      name.startsWith('12.approvals:') ||
                      name == '12.approved-by: package-maintainer'
                    )

                  const approvals = new Set(
                    (await github.paginate(github.rest.pulls.listReviews, {
                      ...context.repo,
                      pull_number: pull_request.number
                    }))
                    .filter(review => review.state == 'APPROVED')
                    .map(review => review.user.id)
                  )

                  const maintainers = new Set(Object.keys(
                    JSON.parse(await readFile(`${pull_request.number}/maintainers.json`, 'utf-8'))
                  ).map(m => Number.parseInt(m, 10)))

                  // And the labels that should be there
                  const after = JSON.parse(await readFile(`${pull_request.number}/changed-paths.json`, 'utf-8')).labels
                  if (approvals.size > 0) after.push(`12.approvals: ${approvals.size > 2 ? '3+' : approvals.size}`)
                  if (Array.from(maintainers).some(m => approvals.has(m))) after.push('12.approved-by: package-maintainer')

                  // Remove the ones not needed anymore
                  await Promise.all(
                    before.filter(name => !after.includes(name))
                    .map(name => github.rest.issues.removeLabel({
                      ...context.repo,
                      issue_number: pull_request.number,
                      name
                    }))
                  )

                  // And add the ones that aren't set already
                  const added = after.filter(name => !before.includes(name))
                  if (added.length > 0) {
                    await github.rest.issues.addLabels({
                      ...context.repo,
                      issue_number: pull_request.number,
                      labels: added
                    })
                  }
                } catch (cause) {
                  throw new Error(`Labeling PR #${pull_request.number} failed.`, { cause })
                }
              })))
              .filter(({ status }) => status == 'rejected')
              .map(({ reason }) => core.setFailed(`${reason.message}\n${reason.cause.stack}`))
            )

      - uses: actions/labeler@8558fd74291d67161a8a78ce36a881fa63b766a9 # v5.0.0
        name: Labels from touched files
        if: |
          github.event_name == 'pull_request_target' &&
          github.event.pull_request.head.repo.owner.login != 'NixOS' || !(
            github.head_ref == 'haskell-updates' ||
            github.head_ref == 'python-updates' ||
            github.head_ref == 'staging-next' ||
            startsWith(github.head_ref, 'staging-next-')
          )
        with:
          repo-token: ${{ secrets.GITHUB_TOKEN }}
          configuration-path: .github/labeler.yml # default
          sync-labels: true

      - uses: actions/labeler@8558fd74291d67161a8a78ce36a881fa63b766a9 # v5.0.0
        name: Labels from touched files (no sync)
        if: |
          github.event_name == 'pull_request_target' &&
          github.event.pull_request.head.repo.owner.login != 'NixOS' || !(
            github.head_ref == 'haskell-updates' ||
            github.head_ref == 'python-updates' ||
            github.head_ref == 'staging-next' ||
            startsWith(github.head_ref, 'staging-next-')
          )
        with:
          repo-token: ${{ secrets.GITHUB_TOKEN }}
          configuration-path: .github/labeler-no-sync.yml
          sync-labels: false

      - uses: actions/labeler@8558fd74291d67161a8a78ce36a881fa63b766a9 # v5.0.0
        name: Labels from touched files (development branches)
        # Development branches like staging-next, haskell-updates and python-updates get special labels.
        # This is to avoid the mass of labels there, which is mostly useless - and really annoying for
        # the backport labels.
        if: |
          github.event_name == 'pull_request_target' &&
          github.event.pull_request.head.repo.owner.login == 'NixOS' && (
            github.head_ref == 'haskell-updates' ||
            github.head_ref == 'python-updates' ||
            github.head_ref == 'staging-next' ||
            startsWith(github.head_ref, 'staging-next-')
          )
        with:
          repo-token: ${{ secrets.GITHUB_TOKEN }}
          configuration-path: .github/labeler-development-branches.yml
          sync-labels: true