feat: try local apidiff

Author: erikburt

.github/workflows/api-diff.yml

@@ -23,3 +23,24 @@ jobs:
       - uses: joelanford/go-apidiff@60c4206be8f84348ebda2a3e0c3ac9cb54b8f685 # v0.8.3
         with:
           version: "v0.8.3"
+
+  analyze-apidiff:
+    permissions:
+      pull-requests: write
+      contents: read
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Go
+        uses: ./.github/actions/setup-go
+        with:
+          go-version-file: "go.mod"
+          only-modules: "true"
+
+      - name: Run script/apidiff.sh
+        run: |
+          ./script/apidiff.sh

script/apidiff.sh

@@ -0,0 +1,101 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# script/apidiff.sh
+# Compare API of only modified Go packages between PR HEAD and default branch using apidiff.
+# Usage: ./script/apidiff.sh
+
+# Ensure apidiff is installed
+if ! command -v apidiff &> /dev/null; then
+  echo "apidiff not found"
+  exit 1
+fi
+
+# Locate repository root
+repo_root=$(git rev-parse --show-toplevel)
+cd "$repo_root"
+
+echo "Repository root: $repo_root"
+
+# Determine default branch (e.g. main or master)
+default_branch=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's|refs/remotes/origin/||' || echo "main")
+echo "Default branch: $default_branch"
+
+# Fetch latest origin
+git fetch origin "$default_branch"
+
+# Determine modified directories containing Go files
+mapfile -t changed_dirs < <(git diff --name-only "origin/$default_branch...HEAD" | grep '\.go$' | xargs -n1 dirname | sort -u)
+if [ ${#changed_dirs[@]} -eq 0 ]; then
+  echo "No modified Go files detected relative to origin/$default_branch. Exiting."
+  exit 0
+fi
+
+echo "Modified directories: ${changed_dirs[*]}"
+
+# Create temporary workspace
+tmp_dir=$(mktemp -d)
+trap 'rm -rf "$tmp_dir"' EXIT
+
+# Add worktrees for default branch and PR HEAD
+git worktree add "$tmp_dir/base" "origin/$default_branch"
+git worktree add "$tmp_dir/head" HEAD
+
+# Resolve import paths for changed directories using head worktree
+declare -a pkgs
+for dir in "${changed_dirs[@]}"; do
+  pkg_path=$(cd "$tmp_dir/head" && go list "./$dir")
+  pkgs+=("$pkg_path")
+done
+# Deduplicate
+mapfile -t pkgs < <(printf '%s
+' "${pkgs[@]}" | sort -u)
+
+echo "Packages to compare: ${pkgs[*]}"
+
+# Prepare export directories
+exports_dir="$tmp_dir/exports"
+base_exports="$exports_dir/base"
+head_exports="$exports_dir/head"
+mkdir -p "$base_exports" "$head_exports"
+
+# Generate exports for specified packages
+generate_pkg_exports() {
+  local tree_path=$1 dest_dir=$2
+  pushd "$tree_path" > /dev/null
+  for pkg in "${pkgs[@]}"; do
+    local rel_name=${pkg//\//_}.export
+    echo "Writing export for $pkg -> $dest_dir/$rel_name"
+    apidiff -w "$dest_dir/$rel_name" "$pkg"
+  done
+  popd > /dev/null
+}
+
+# Run exports
+generate_pkg_exports "$tmp_dir/base" "$base_exports"
+generate_pkg_exports "$tmp_dir/head" "$head_exports"
+
+# Compare exports for breaking changes
+echo -e "\nComparing API for breaking changes..."
+broken=false
+for pkg in "${pkgs[@]}"; do
+  file=${pkg//\//_}.export
+  base_file="$base_exports/$file"
+  head_file="$head_exports/$file"
+  echo -e "\nChecking $pkg"
+  if ! apidiff "$base_file" "$head_file"; then
+    broken=true
+  fi
+done
+
+# Cleanup worktrees
+git worktree remove "$tmp_dir/base" --force
+git worktree remove "$tmp_dir/head" --force
+
+# Exit status based on breakages
+if [[ "$broken" == true ]]; then
+  echo -e "\nBreaking API changes detected."
+  exit 1
+else
+  echo -e "\nNo breaking API changes detected."
+fi