Add an action to validate generated code

.github/workflows/validate-generated-code.yaml

@@ -0,0 +1,28 @@
+name: "Validate Generated Code"
+
+on:
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  my_first_job:
+    steps:
+      - name: My first step
+        uses: docker://gcr.io/cloud-builders/gradle
+
+jobs:
+  analyze:
+    name: Analyze
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+    - name: Generate code
+      uses: docker://gcr.io/pipecd/codegen:0.2.0
+      with:
+        args: /github/workspace
+     - name: Show Git status
+      shell: bash
+      run: git status
+    - name: Validate
+      shell: bash
+      run: test -z "$(git status --porcelain)"

Makefile

@@ -133,4 +133,4 @@ update-docsy:
 
 .PHONY: codegen
 codegen:
-	docker run --rm -v ${PWD}:/repo -it gcr.io/pipecd/codegen:0.1.0
+	docker run --rm -v ${PWD}:/repo -it gcr.io/pipecd/codegen:0.2.0 /repo

dockers/codegen/DOCKER_BUILD

@@ -1,2 +1,2 @@
-version: 0.1.0
+version: 0.2.0
 registry: gcr.io/pipecd/codegen

dockers/codegen/codegen.sh

@@ -4,6 +4,14 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
+while [[ -z "$1" ]]
+do
+    echo "Missing path to the root of repository"
+    exit 1
+done
+
+cd $1
+
 # Generate Go files from proto files.
 goProtoDirs=(
   "pkg/model"