Diff generated code from proto files (#4863)

Add a static check that ensures the generated files from the proto definitions have not changed. 

Fix #4669

Signed-off-by: Zahari Dichev <zaharidichev@gmail.com>

.github/workflows/static_checks.yml

@@ -30,6 +30,17 @@ jobs:
       uses: actions/checkout@722adc6
     - name: Format
       run: bin/fmt
+  proto_diff:
+    name: Proto diff
+    runs-on: ubuntu-18.04
+    container:
+      image: golang:1.13.4
+    steps:
+      - name: Checkout code
+        # actions/checkout@v2
+        uses: actions/checkout@722adc6
+      - name: Diff proto files
+        run: bin/protoc-diff
   shellcheck:
     name: shellcheck
     runs-on: ubuntu-18.04

bin/protoc-diff

@@ -0,0 +1,22 @@
+#!/usr/bin/env sh
+
+set -eu
+
+# Install unzip if not already installed (Linux only)
+system=$(uname -s)
+if [ "$system" = Linux ] && ! [ -x "$(command -v unzip)" ]; then
+  apt-get update
+  apt-get install unzip
+fi
+
+bin/protoc-go.sh
+
+dir_dirty=$(git diff HEAD)
+if [ -z "$dir_dirty" ]; then
+  echo "Protobuf definitions match generated code"
+  exit 0
+else
+  echo "Protobuf definitions diverge from generated code:"
+  echo "$(git status)"
+  exit 64
+fi