CI: Skip aio jobs based on changed files

We don't always want to run all aio jobs - it can be wasteful of CI
resources and slows down merging changes.

This change uses the dorny/paths-filter action to detect changed files
and skip jobs as appropriate.

Note that we can't use the workflow-level paths attribute since this
would skip the workflow entirely, and would prevent us from making the
aio jobs required to pass (a skip counts as a pass).

Author: markgoddard

.github/path-filters.yml

@@ -0,0 +1,36 @@
+# This file is a list of path filters for the PR workflow in .github/workflows/stackhpc-pull-request.yml.
+aio:
+  - '.automation'
+  - '.automation.conf/config.sh'
+  - '.automation.conf/tempest/load-lists/default'
+  - '.automation.conf/tempest/load-lists/platform.2022.11-test-list.txt'
+  - '.automation.conf/tempest/load-lists/refstack-2019.11-test-list.txt'
+  - '.automation.conf/tempest/tempest-ci-aio.overrides.conf'
+  - '.github/workflows/stackhpc-all-in-one.yml'
+  - '.github/workflows/stackhpc-build-kayobe-image.yml'
+  - '.github/workflows/stackhpc-pull-request-aio.yml'
+  - 'etc/kayobe/**'
+  - '!etc/kayobe/ansible/**'
+  - 'etc/kayobe/ansible/configure-aio-resources.yml'
+  - 'etc/kayobe/ansible/growroot.yml'
+  - 'etc/kayobe/ansible/requirements.yml'
+  - 'etc/kayobe/ansible/scripts/aio-init.sh'
+  - '!etc/kayobe/bifrost.yml'
+  - '!etc/kayobe/bmc.yml'
+  - '!etc/kayobe/cephadm.yml'
+  - '!etc/kayobe/containers/**'
+  - '!etc/kayobe/environments/aufn-ceph/**'
+  - '!etc/kayobe/environments/ci-builder/**'
+  - '!etc/kayobe/environments/ci-multinode/**'
+  - '!etc/kayobe/inspector.yml'
+  - '!etc/kayobe/ipa.yml'
+  - '!etc/kayobe/kolla/config/bifrost/bifrost.yml'
+  - '!etc/kayobe/kolla/kolla-build.conf'
+  - '!etc/kayobe/overcloud-dib.yml'
+  - '!etc/kayobe/seed*'
+  - '!etc/kayobe/stackhpc-overcloud-dib.yml'
+  - '!etc/kayobe/stackhpc-overcloud-host-images.yml'
+  - '!etc/kayobe/vault.yml'
+  - 'kayobe-env'
+  - 'requirements.txt'
+  - 'terraform/aio/**'

.github/workflows/stackhpc-pull-request.yml

@@ -8,6 +8,25 @@ name: Pull request
 'on':
   pull_request:
 jobs:
+  # Detect which files have changed and use this to run jobs conditionally.
+  # Note that we can't use the workflow-level paths attribute since this
+  # would skip the workflow entirely, and would prevent us from making the
+  # aio jobs required to pass (a skip counts as a pass).
+  check-changes:
+    runs-on: ubuntu-20.04
+    permissions:
+      pull-requests: read
+    name: Check changed files
+    if: github.repository == 'stackhpc/stackhpc-kayobe-config'
+    outputs:
+      aio: ${{ steps.changes.outputs.aio }}
+    steps:
+      - name: Check changed files
+        uses: dorny/path-filter@v2
+        id: changes
+        with:
+          # Filters are defined in this file.
+          filters: .github/path-filters.yml
   tox:
     runs-on: ubuntu-20.04
     permissions: {}
@@ -36,8 +55,12 @@ jobs:
 
   build-kayobe-image:
     name: Build Kayobe Image
+    needs:
+      - check-changes
     uses: ./.github/workflows/stackhpc-build-kayobe-image.yml
-    if: github.repository == 'stackhpc/stackhpc-kayobe-config'
+    if:
+      - github.repository == 'stackhpc/stackhpc-kayobe-config'
+      - needs.check-changes.outputs.aio == 'true'
 
   all-in-one-centos-ovs:
     name: aio (CentOS OVS)