From dac20e22a386f6bde91fe7e2824444c8c6fa51ad Mon Sep 17 00:00:00 2001
From: kruskall <99559985+kruskall@users.noreply.github.com>
Date: Thu, 12 Sep 2024 01:47:48 +0200
Subject: [PATCH 1/2] feat(apm-*): only build docs if there's a doc change

extend the check to all apm repositories and use a switch to
make it easier to add more repo that share common file patterns
---
 .buildkite/scripts/build_pr.sh | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/.buildkite/scripts/build_pr.sh b/.buildkite/scripts/build_pr.sh
index caf05ea2979c..85923e6f7e8b 100755
--- a/.buildkite/scripts/build_pr.sh
+++ b/.buildkite/scripts/build_pr.sh
@@ -54,12 +54,27 @@ if [[ "${GITHUB_PR_BASE_REPO}" != 'docs' ]]; then
       git fetch origin pull/$GITHUB_PR_NUMBER/head:pr_$GITHUB_PR_NUMBER &&
       git switch pr_$GITHUB_PR_NUMBER
 
-  if [[ "${GITHUB_PR_BASE_REPO}" == 'apm-agent-go' ]]; then
-    git fetch origin "$GITHUB_PR_TARGET_BRANCH"
-    docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs CHANGELOG.asciidoc)
-  else
-    docs_diff="always build"
-  fi
+  case $GITHUB_PR_BASE_REPO in
+
+    "apm-aws-lambda" | "apm-agent-android" | "apm-agent-nodejs" | "apm-agent-python" | "apm-agent-ruby" | "apm-agent-rum-js" | "apm-agent-go" | "apm-agent-java" | "apm-agent-dotnet" | "apm-agent-php" | "apm-agent-ios")
+      git fetch origin "$GITHUB_PR_TARGET_BRANCH"
+      docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs CHANGELOG.asciidoc)
+      ;;
+
+    "apm-k8s-attacher")
+      git fetch origin "$GITHUB_PR_TARGET_BRANCH"
+      docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs)
+      ;;
+
+    "apm-server")
+      git fetch origin "$GITHUB_PR_TARGET_BRANCH"
+      docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs ./changelogs CHANGELOG.asciidoc)
+      ;;
+
+    *)
+      docs_diff="always build"
+      ;;
+  esac
 
   if [[ -z $docs_diff ]]; then
     echo "pull/${GITHUB_PR_NUMBER} in ${GITHUB_PR_BASE_REPO} has no docs changes compared to ${GITHUB_PR_TARGET_BRANCH}"

From 0772c90620b832aca950f55b207957910b6c2163 Mon Sep 17 00:00:00 2001
From: Brandon Morelli <bmorelli25@gmail.com>
Date: Wed, 11 Sep 2024 17:46:47 -0700
Subject: [PATCH 2/2] add comments

---
 .buildkite/scripts/build_pr.sh | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/.buildkite/scripts/build_pr.sh b/.buildkite/scripts/build_pr.sh
index 85923e6f7e8b..70fa3c9cd8ce 100755
--- a/.buildkite/scripts/build_pr.sh
+++ b/.buildkite/scripts/build_pr.sh
@@ -54,33 +54,42 @@ if [[ "${GITHUB_PR_BASE_REPO}" != 'docs' ]]; then
       git fetch origin pull/$GITHUB_PR_NUMBER/head:pr_$GITHUB_PR_NUMBER &&
       git switch pr_$GITHUB_PR_NUMBER
 
+  # Some repositories allow the documentation build to exit early if there are no doc-related changes
+  # For these repos, we fetch the latest changes from the target branch of the pull request and check
+  # for changes in specified files and directories with git diff.
   case $GITHUB_PR_BASE_REPO in
 
+    # repositories with a docs dir and changelog
     "apm-aws-lambda" | "apm-agent-android" | "apm-agent-nodejs" | "apm-agent-python" | "apm-agent-ruby" | "apm-agent-rum-js" | "apm-agent-go" | "apm-agent-java" | "apm-agent-dotnet" | "apm-agent-php" | "apm-agent-ios")
       git fetch origin "$GITHUB_PR_TARGET_BRANCH"
       docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs CHANGELOG.asciidoc)
       ;;
-
+      
+    # repositories with a docs dir
     "apm-k8s-attacher")
       git fetch origin "$GITHUB_PR_TARGET_BRANCH"
       docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs)
       ;;
-
+      
+    # repositories with a docs dir, changelogs dir, and changelog
     "apm-server")
       git fetch origin "$GITHUB_PR_TARGET_BRANCH"
       docs_diff=$(git diff --stat "origin/$GITHUB_PR_TARGET_BRANCH"...HEAD -- ./docs ./changelogs CHANGELOG.asciidoc)
       ;;
 
+    # All other repos will always build
     *)
       docs_diff="always build"
       ;;
   esac
 
+  # If docs_diff is empty, exit early and succeed
   if [[ -z $docs_diff ]]; then
     echo "pull/${GITHUB_PR_NUMBER} in ${GITHUB_PR_BASE_REPO} has no docs changes compared to ${GITHUB_PR_TARGET_BRANCH}"
     exit 0
   fi
 
+  # Regardless of whether we build or not, we print out the diff
   echo "diff:"
   echo "$docs_diff"