ci: Convert runner select to composite action (#39270)

to run bencher builds on self-hosted runners (#39269), we will need to
do a self-hosted runner select, but that would exceed the workflow call
depth limit (try → dispatch-workflow → linux → bencher →
self-hosted-runner-select).

this patch converts the self-hosted runner select from a [reusable
workflow](https://docs.github.com/en/actions/concepts/workflows-and-actions/reusable-workflows)
to a [composite
action](https://docs.github.com/en/actions/tutorials/create-actions/create-a-composite-action),
much like #38503 did for the runner timeout.

Testing:
- self-hosted
<https://github.com/servo/servo/actions/runs/17674919359/job/50235098986>
- GitHub-hosted
<https://github.com/delan/servo/actions/runs/17674928875/job/50234708810>

Fixes: part of #39269

---------

Signed-off-by: Delan Azabani <dazabani@igalia.com>

.github/actions/runner-select/action.yml

@@ -0,0 +1,100 @@
+name: Select Self-hosted Runner
+inputs:
+  monitor-api-token:
+    required: true
+    type: string
+  github-hosted-runner-label:
+    required: true
+    type: string
+  self-hosted-image-name:
+    required: true
+    type: string
+  self-hosted-runner-scope:
+    required: false
+    type: string
+    default: /orgs/${{ github.repository_owner }}/actions/runners
+  force-github-hosted-runner:
+    required: false
+    type: boolean
+    default: false
+  NO_SELF_HOSTED_RUNNERS:
+    required: false
+    type: string
+    default: ""
+outputs:
+  unique-id:
+    value: ${{ steps.select.outputs.unique_id }}
+  selected-runner-label:
+    value: ${{ steps.select.outputs.selected_runner_label }}
+  is-self-hosted:
+    value: ${{ steps.select.outputs.is_self_hosted }}
+
+runs:
+  using: "composite"
+  # Selects a self-hosted runner if available, or else a GitHub-hosted runner.
+  # We generate a unique id for the workload, then ask our monitor API to
+  # reserve a self-hosted runner for us.
+  steps:
+    - name: Select and reserve best available runner
+      id: select
+      shell: bash
+      run: |
+        github_hosted_runner_label='${{ inputs.github-hosted-runner-label }}'
+        self_hosted_image_name='${{ inputs.self-hosted-image-name }}'
+        self_hosted_runner_scope='${{ inputs.self-hosted-runner-scope }}'
+
+        set -euo pipefail
+
+        fall_back_to_github_hosted() {
+          echo 'Falling back to GitHub-hosted runner'
+          echo "selected_runner_label=$github_hosted_runner_label" | tee -a $GITHUB_OUTPUT
+          echo 'is_self_hosted=false' | tee -a $GITHUB_OUTPUT
+          exit 0
+        }
+
+        # Generate a unique id that allows the workload job to find the runner
+        # we are reserving for it (via runner labels), and allows the timeout
+        # job to find the workload job run (via the job’s friendly name), even
+        # if there are multiple instances in the workflow call tree.
+        unique_id=$(uuidgen)
+        echo "unique_id=$unique_id" | tee -a $GITHUB_OUTPUT
+
+        # Disable self-hosted runners by creating a repository variable named
+        # NO_SELF_HOSTED_RUNNERS with any non-empty value.
+        # <https://github.com/servo/servo/settings/variables/actions>
+        if [ -n '${{ inputs.NO_SELF_HOSTED_RUNNERS }}' ]; then
+          echo 'NO_SELF_HOSTED_RUNNERS is set!'
+          fall_back_to_github_hosted
+        fi
+
+        if [ '${{ inputs.force-github-hosted-runner }}' = true ]; then
+          echo 'inputs.force-github-hosted-runner is set!'
+          fall_back_to_github_hosted
+        fi
+
+        for monitor_api_base_url in $(printf \%s\\n \
+          https://ci0.servo.org \
+          https://ci1.servo.org \
+          https://ci2.servo.org \
+        | shuf); do
+          # Use the monitor API to reserve a runner. If we get an object with
+          # runner details, we succeeded. If we get null, we failed.
+          take_runner_url=$monitor_api_base_url/profile/$self_hosted_image_name/take\?unique_id=$unique_id\&qualified_repo=${{ github.repository }}\&run_id=${{ github.run_id }}
+          result=$(mktemp)
+          echo
+          echo POST "$take_runner_url"
+          if curl -sS --fail-with-body --connect-timeout 5 --max-time 30 -X POST "$take_runner_url" \
+              -H 'Authorization: Bearer ${{ inputs.monitor-api-token }}' > $result \
+              && jq -e . $result > /dev/null; then
+            echo
+            echo "selected_runner_label=reserved-for:$unique_id" | tee -a $GITHUB_OUTPUT
+            echo 'is_self_hosted=true' | tee -a $GITHUB_OUTPUT
+            exit 0
+          fi
+        done
+
+        cat $result
+        echo
+        echo
+        echo 'No self-hosted runners available!'
+        fall_back_to_github_hosted

.github/workflows/linux.yml

@@ -99,15 +99,32 @@ jobs:
   # Runs the underlying job (“workload”) on a self-hosted runner if available,
   # with the help of a `runner-select` job and a `runner-timeout` job.
   runner-select:
-    uses: ./.github/workflows/self-hosted-runner-select.yml
+    runs-on: ubuntu-22.04
-    secrets: inherit
+    outputs:
-    with:
+      unique-id: ${{ steps.select.outputs.unique-id }}
-      # Before updating the GH action runner image for the nightly job, ensure
+      selected-runner-label: ${{ steps.select.outputs.selected-runner-label }}
-      # that the system has a glibc version that is compatible with the one
+      is-self-hosted: ${{ steps.select.outputs.is-self-hosted }}
-      # used by the wpt.fyi runners.
+    steps:
-      github-hosted-runner-label: ubuntu-22.04
+      - name: Checkout
-      self-hosted-image-name: servo-ubuntu2204
+        uses: actions/checkout@v4
-      force-github-hosted-runner: ${{ inputs.upload || inputs.force-github-hosted-runner }}
+        with:
+          sparse-checkout: '.github'
+      - name: Runner select
+        id: select
+        uses: ./.github/actions/runner-select
+        with:
+          monitor-api-token: ${{ secrets.SERVO_CI_MONITOR_API_TOKEN }}
+          # Before updating the GH action runner image for the nightly job, ensure
+          # that the system has a glibc version that is compatible with the one
+          # used by the wpt.fyi runners.
+          github-hosted-runner-label: ubuntu-22.04
+          self-hosted-image-name: servo-ubuntu2204
+          # You can disable self-hosted runners globally by creating a repository variable named
+          # NO_SELF_HOSTED_RUNNERS with any non-empty value.
+          # <https://github.com/servo/servo/settings/variables/actions>
+          NO_SELF_HOSTED_RUNNERS: ${{ vars.NO_SELF_HOSTED_RUNNERS }}
+          # Any other boolean conditions that disable self-hosted runners go here.
+          force-github-hosted-runner: ${{ inputs.upload || inputs.force-github-hosted-runner }}
   runner-timeout:
     needs:
       - runner-select

.github/workflows/mac.yml

@@ -85,12 +85,29 @@ jobs:
   # Runs the underlying job (“workload”) on a self-hosted runner if available,
   # with the help of a `runner-select` job and a `runner-timeout` job.
   runner-select:
-    uses: ./.github/workflows/self-hosted-runner-select.yml
+    runs-on: ubuntu-22.04
-    secrets: inherit
+    outputs:
-    with:
+      unique-id: ${{ steps.select.outputs.unique-id }}
-      github-hosted-runner-label: macos-13
+      selected-runner-label: ${{ steps.select.outputs.selected-runner-label }}
-      self-hosted-image-name: servo-macos13
+      is-self-hosted: ${{ steps.select.outputs.is-self-hosted }}
-      force-github-hosted-runner: ${{ inputs.force-github-hosted-runner }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          sparse-checkout: '.github'
+      - name: Runner select
+        id: select
+        uses: ./.github/actions/runner-select
+        with:
+          monitor-api-token: ${{ secrets.SERVO_CI_MONITOR_API_TOKEN }}
+          github-hosted-runner-label: macos-13
+          self-hosted-image-name: servo-macos13
+          # You can disable self-hosted runners globally by creating a repository variable named
+          # NO_SELF_HOSTED_RUNNERS with any non-empty value.
+          # <https://github.com/servo/servo/settings/variables/actions>
+          NO_SELF_HOSTED_RUNNERS: ${{ vars.NO_SELF_HOSTED_RUNNERS }}
+          # Any other boolean conditions that disable self-hosted runners go here.
+          force-github-hosted-runner: ${{ inputs.force-github-hosted-runner }}
   runner-timeout:
     needs:
       - runner-select

.github/workflows/self-hosted-runner-select.yml

@@ -1,100 +0,0 @@
-name: Select Self-hosted Runner
-on:
-  workflow_call:
-    inputs:
-      github-hosted-runner-label:
-        required: true
-        type: string
-      self-hosted-image-name:
-        required: true
-        type: string
-      self-hosted-runner-scope:
-        required: false
-        type: string
-        default: /orgs/${{ github.repository_owner }}/actions/runners
-      force-github-hosted-runner:
-        required: false
-        type: boolean
-        default: false
-    outputs:
-      unique-id:
-        value: ${{ jobs.runner-select.outputs.unique-id }}
-      selected-runner-label:
-        value: ${{ jobs.runner-select.outputs.selected-runner-label }}
-      is-self-hosted:
-        value: ${{ jobs.runner-select.outputs.is-self-hosted }}
-
-jobs:
-  # Selects a self-hosted runner if available, or else a GitHub-hosted runner.
-  # We generate a unique id for the workload, then ask our monitor API to
-  # reserve a self-hosted runner for us.
-  runner-select:
-    name: Select Runner
-    runs-on: ubuntu-latest
-    outputs:
-      unique-id: ${{ steps.select.outputs.unique_id }}
-      selected-runner-label: ${{ steps.select.outputs.selected_runner_label }}
-      is-self-hosted: ${{ steps.select.outputs.is_self_hosted }}
-    steps:
-      - name: Select and reserve best available runner
-        id: select
-        run: |
-          github_hosted_runner_label='${{ inputs.github-hosted-runner-label }}'
-          self_hosted_image_name='${{ inputs.self-hosted-image-name }}'
-          self_hosted_runner_scope='${{ inputs.self-hosted-runner-scope }}'
-
-          set -euo pipefail
-
-          fall_back_to_github_hosted() {
-            echo 'Falling back to GitHub-hosted runner'
-            echo "selected_runner_label=$github_hosted_runner_label" | tee -a $GITHUB_OUTPUT
-            echo 'is_self_hosted=false' | tee -a $GITHUB_OUTPUT
-            exit 0
-          }
-
-          # Generate a unique id that allows the workload job to find the runner
-          # we are reserving for it (via runner labels), and allows the timeout
-          # job to find the workload job run (via the job’s friendly name), even
-          # if there are multiple instances in the workflow call tree.
-          unique_id=$(uuidgen)
-          echo "unique_id=$unique_id" | tee -a $GITHUB_OUTPUT
-
-          # Disable self-hosted runners by creating a repository variable named
-          # NO_SELF_HOSTED_RUNNERS with any non-empty value.
-          # <https://github.com/servo/servo/settings/variables/actions>
-          if [ -n '${{ vars.NO_SELF_HOSTED_RUNNERS }}' ]; then
-            echo 'NO_SELF_HOSTED_RUNNERS is set!'
-            fall_back_to_github_hosted
-          fi
-
-          if [ '${{ inputs.force-github-hosted-runner }}' = true ]; then
-            echo 'inputs.force-github-hosted-runner is set!'
-            fall_back_to_github_hosted
-          fi
-
-          for monitor_api_base_url in $(printf \%s\\n \
-            https://ci0.servo.org \
-            https://ci1.servo.org \
-            https://ci2.servo.org \
-          | shuf); do
-            # Use the monitor API to reserve a runner. If we get an object with
-            # runner details, we succeeded. If we get null, we failed.
-            take_runner_url=$monitor_api_base_url/profile/$self_hosted_image_name/take\?unique_id=$unique_id\&qualified_repo=${{ github.repository }}\&run_id=${{ github.run_id }}
-            result=$(mktemp)
-            echo
-            echo POST "$take_runner_url"
-            if curl -sS --fail-with-body --connect-timeout 5 --max-time 30 -X POST "$take_runner_url" \
-                -H 'Authorization: Bearer ${{ secrets.SERVO_CI_MONITOR_API_TOKEN }}' > $result \
-                && jq -e . $result > /dev/null; then
-              echo
-              echo "selected_runner_label=reserved-for:$unique_id" | tee -a $GITHUB_OUTPUT
-              echo 'is_self_hosted=true' | tee -a $GITHUB_OUTPUT
-              exit 0
-            fi
-          done
-
-          cat $result
-          echo
-          echo
-          echo 'No self-hosted runners available!'
-          fall_back_to_github_hosted

.github/workflows/windows.yml

@@ -76,12 +76,29 @@ jobs:
   # Runs the underlying job (“workload”) on a self-hosted runner if available,
   # with the help of a `runner-select` job and a `runner-timeout` job.
   runner-select:
-    uses: ./.github/workflows/self-hosted-runner-select.yml
+    runs-on: ubuntu-22.04
-    secrets: inherit
+    outputs:
-    with:
+      unique-id: ${{ steps.select.outputs.unique-id }}
-      github-hosted-runner-label: windows-2022
+      selected-runner-label: ${{ steps.select.outputs.selected-runner-label }}
-      self-hosted-image-name: servo-windows10
+      is-self-hosted: ${{ steps.select.outputs.is-self-hosted }}
-      force-github-hosted-runner: ${{ inputs.force-github-hosted-runner }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          sparse-checkout: '.github'
+      - name: Runner select
+        id: select
+        uses: ./.github/actions/runner-select
+        with:
+          monitor-api-token: ${{ secrets.SERVO_CI_MONITOR_API_TOKEN }}
+          github-hosted-runner-label: windows-2022
+          self-hosted-image-name: servo-windows10
+          # You can disable self-hosted runners globally by creating a repository variable named
+          # NO_SELF_HOSTED_RUNNERS with any non-empty value.
+          # <https://github.com/servo/servo/settings/variables/actions>
+          NO_SELF_HOSTED_RUNNERS: ${{ vars.NO_SELF_HOSTED_RUNNERS }}
+          # Any other boolean conditions that disable self-hosted runners go here.
+          force-github-hosted-runner: ${{ inputs.force-github-hosted-runner }}
   runner-timeout:
     needs:
       - runner-select