From 5c728cbb30ba48bfc28f543aa05d751bf9a50527 Mon Sep 17 00:00:00 2001
From: Scott Dickerson <sdickers@redhat.com>
Date: Thu, 12 Sep 2024 13:56:11 -0400
Subject: [PATCH] :seedling: Skip PR CI actions for docs/hacks changes (#2084)

When a PR only contains changes to root level markdown, or anything
under `docs/` or `hack/`, there is no need to run the CI github actions.

To satisfy branch protection rules that may exist that require the
"unit-test" job to run, the `ci-repo.yml` action looks up details about
a PR and will skip the unit test if it detects that the only changes
made in the PR are docs or hacks.

The ignores do not apply to pushes to main, pushes to release, or
workflow calls.

Signed-off-by: Scott J Dickerson <sdickers@redhat.com>
---
 .github/workflows/ci-global.yml      |  4 ++
 .github/workflows/ci-image-build.yml |  4 ++
 .github/workflows/ci-repo.yml        | 59 ++++++++++++++++++++++++++--
 3 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/ci-global.yml b/.github/workflows/ci-global.yml
index f6d8d6d618..3497b0acc9 100644
--- a/.github/workflows/ci-global.yml
+++ b/.github/workflows/ci-global.yml
@@ -6,6 +6,10 @@ on:
       - "main"
 
   pull_request:
+    paths-ignore:
+      - "docs/**"
+      - "hack/**"
+      - "*.md"
     branches:
       - "main"
 
diff --git a/.github/workflows/ci-image-build.yml b/.github/workflows/ci-image-build.yml
index 6199750d93..6a165b27df 100644
--- a/.github/workflows/ci-image-build.yml
+++ b/.github/workflows/ci-image-build.yml
@@ -2,6 +2,10 @@ name: CI (test image build for a PR with build related changes)
 
 on:
   pull_request:
+    paths-ignore:
+      - "docs/**"
+      - "hack/**"
+      - "*.md"
     branches:
       - "main"
       - "release-*"
diff --git a/.github/workflows/ci-repo.yml b/.github/workflows/ci-repo.yml
index 9920661914..3089ef5174 100644
--- a/.github/workflows/ci-repo.yml
+++ b/.github/workflows/ci-repo.yml
@@ -20,10 +20,12 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  unit-test-lookup-image:
+  unit-test-lookup:
     runs-on: ubuntu-latest
     outputs:
       builder-image: ${{ steps.grepBuilder.outputs.builder }}
+      should-test: ${{ steps.check-changes.outputs.should-test }}
+
     steps:
       - uses: actions/checkout@v4
 
@@ -31,15 +33,64 @@ jobs:
         id: grepBuilder
         run: |
           builder=$(grep 'as builder' Dockerfile | sed -e 's/^FROM \(.*\) as builder$/\1/')
-          echo "Builder image: \`$builder\`" >> "$GITHUB_STEP_SUMMARY"
           echo "builder=$builder" >> "$GITHUB_OUTPUT"
 
+      - name: Did docs and hacks change?
+        id: docs-and-hacks
+        uses: tj-actions/changed-files@v44
+        with:
+          files: |
+            docs/**
+            hack/**
+            *.md
+
+      - name: Check if only docs and hacks changes have been made in a PR
+        id: check-changes
+        env:
+          IS_PR: ${{ !!github.event.pull_request }}
+          ONLY_DOCS: ${{ steps.docs-and-hacks.outputs.only_modified }}
+        run: |
+          SHOULD_TEST=$(
+            if [[ $IS_PR == true ]] && [[ $ONLY_DOCS == true ]]; then
+              echo "false"
+            else
+              echo "true"
+            fi
+          )
+
+          echo "is-pr=$IS_PR" >> "$GITHUB_OUTPUT"
+          echo "changes_only_docs=${ONLY_DOCS:-false}" >> "$GITHUB_OUTPUT"
+          echo "should-test=$SHOULD_TEST" >> "$GITHUB_OUTPUT"
+
+      - name: Summarize findings
+        env:
+          ONLY_DOCS: ${{ steps.docs-and-hacks.outputs.only_modified }}
+          MODIFIED_FILES: ${{ steps.docs-and-hacks.outputs.all_modified_files }}
+        run: |
+          cat >> "$GITHUB_STEP_SUMMARY" <<EOF
+          ## Build container
+            - CI will run on container: \`${{ steps.grepBuilder.outputs.builder }}\`
+
+          ## Findings
+            - The action is PR triggered? \`${{ steps.check-changes.outputs.is-pr }}\`
+            - Changes are only to docs and hacks? \`${{ steps.check-changes.outputs.changes_only_docs }}\`
+            - Should the unit test run? \`${{ steps.check-changes.outputs.should-test }}\`
+          EOF
+
+          if [[ $ONLY_DOCS == true ]] && [[ -n "$MODIFIED_FILES" ]]; then
+            echo "## Modified docs and hacks files that do not impact the build" >> "$GITHUB_STEP_SUMMARY"
+            for file in ${MODIFIED_FILES}; do
+              echo "  - \`$file\`" >> "$GITHUB_STEP_SUMMARY"
+            done
+          fi
+
   unit-test:
     runs-on: ubuntu-latest
-    needs: unit-test-lookup-image
+    needs: unit-test-lookup
+    if: ${{ needs.unit-test-lookup.outputs.should-test == 'true' }}
 
     # Use the same container as the Dockerfile's "FROM * as builder"
-    container: ${{ needs.unit-test-lookup-image.outputs.builder-image }}
+    container: ${{ needs.unit-test-lookup.outputs.builder-image }}
 
     steps:
       - uses: actions/checkout@v4