feat: try local apidiff

Author: erikburt

.github/workflows/api-diff.yml

@@ -3,7 +3,28 @@ on:
   pull_request:
 
 jobs:
-  analyze:
+  # analyze:
+  #   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"
+
+  #     - uses: joelanford/go-apidiff@60c4206be8f84348ebda2a3e0c3ac9cb54b8f685 # v0.8.3
+  #       with:
+  #         version: "v0.8.3"
+
+  analyze-apidiff:
     permissions:
       pull-requests: write
       contents: read
@@ -20,6 +41,7 @@ jobs:
           go-version-file: "go.mod"
           only-modules: "true"
 
-      - uses: joelanford/go-apidiff@60c4206be8f84348ebda2a3e0c3ac9cb54b8f685 # v0.8.3
-        with:
-          version: "v0.8.3"
+      - name: Run script/apidiff.sh
+        run: |
+          go install golang.org/x/exp/cmd/apidiff@latest
+          ./script/apidiff.sh

script/apidiff.sh

@@ -0,0 +1,106 @@
+#!/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, installing..."
+  go install golang.org/x/exp/apidiff@latest
+fi
+
+# Locate repository root
+repo_root=$(git rev-parse --show-toplevel)
+cd "$repo_root"
+
+echo "Repository root: $repo_root"
+
+# Determine default branch
+default_branch=$(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 Go files relative to base
+raw_changes=$(git diff --name-only "origin/$default_branch...HEAD" -- '*.go')
+if [[ -z "$raw_changes" ]]; then
+  echo "No modified Go files detected relative to origin/$default_branch. Exiting."
+  exit 0
+fi
+
+# Derive unique directories
+readarray -t changed_dirs < <(
+  printf '%s
+' "$raw_changes" |
+  xargs -n1 dirname |
+  sort -u
+)
+
+echo "Modified directories: ${changed_dirs[*]}"
+
+# Create temporary workspace
+tmp_dir=$(mktemp -d)
+trap 'rm -rf "$tmp_dir"' EXIT
+
+# Add worktrees for base and head
+git worktree add "$tmp_dir/base" "origin/$default_branch"
+git worktree add "$tmp_dir/head" HEAD
+
+# Resolve import paths for changed directories
+declare -a pkgs
+for dir in "${changed_dirs[@]}"; do
+  pkg_path=$(cd "$tmp_dir/head" && go list "./$dir")
+  pkgs+=("$pkg_path")
+done
+# Deduplicate
+readarray -t pkgs < <(printf '%s
+' "${pkgs[@]}" | sort -u)
+
+echo "Packages to compare: ${pkgs[*]}"
+
+# Prepare export dirs
+exports_dir="$tmp_dir/exports"
+base_exports="$exports_dir/base"
+head_exports="$exports_dir/head"
+mkdir -p "$base_exports" "$head_exports"
+
+# Generate exports
+generate_pkg_exports() {
+  local tree=$1 dest=$2
+  pushd "$tree" > /dev/null
+  for pkg in "${pkgs[@]}"; do
+    local file=${pkg//\//_}.export
+    echo "Exporting $pkg -> $dest/$file"
+    apidiff -w "$dest/$file" "$pkg"
+  done
+  popd > /dev/null
+}
+
+generate_pkg_exports "$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
+  echo -e "\nChecking $pkg"
+  if ! apidiff "$base_exports/$file" "$head_exports/$file"; then
+    broken=true
+  fi
+done
+
+# Clean up worktrees
+git worktree remove "$tmp_dir/base" --force
+git worktree remove "$tmp_dir/head" --force
+
+# Final status
+if [[ "$broken" == true ]]; then
+  echo -e "\nBreaking API changes detected."
+  exit 1
+else
+  echo -e "\nNo breaking API changes detected."
+fi