CI: pre-commit check for generated files (#199)

* add pre-commit hook to check for swagger updates

* update README with 'make buf-gen'

* put correct exit codes in hook

* remove unnecessary Makefile addition

* update hook to check pb.go files and be blocking

* init-hooks -> init-git-hooks

Co-authored-by: Will Vedder <[email protected]>

* fix makefile dep typo

* change hook message wording to be more accurate

* update README to point out --no-verify

---------

Co-authored-by: Will Vedder <[email protected]>

.githooks/pre-commit

@@ -0,0 +1,29 @@
+#!/bin/sh
+# This is a simple check to ensure people remember to regenerate the docs
+# and the pb.go files if they change a .proto file.
+# It's not iron-clad but it's better than finding out later in github.
+
+# AMD = added, modified, deleted
+files=$(git diff --cached --name-only --diff-filter=AMD)
+
+LIGHT_RED='\033[1;31m'
+RESET='\033[0m' # No Color
+
+# naive regex check for .proto extension
+if [[ "$files" =~ \.proto ]]
+then
+    # Check if there's a staged diff in /docs and in the generated pb.go files
+    docs_change=$(git diff --cached --raw docs/)
+    go_change=$(git diff --cached --raw proto/openfga/)
+    if [ -n "$docs_change" ] && [ -n "$go_change" ]; then
+      # Both were changed, we're good
+      exit 0
+    else
+      # One of the two directories does not have changes, block this commit
+      echo "This commit contains .proto changes but either the docs or generated /proto files are not part of this commit."
+      echo "${LIGHT_RED}Your changes were not committed, please run 'make all' and add the resulting changes${RESET}\n"
+      exit 1
+    fi
+fi
+
+exit 0

Makefile

@@ -1,10 +1,13 @@
 all: patch-swagger-doc format
 
-buf-gen:
+buf-gen: init-git-hooks
 	./buf.gen.yaml
 
 patch-swagger-doc: buf-gen
 	./scripts/update_swagger.sh docs/openapiv2/apidocs.swagger.json
 
 format: buf-gen
 	buf format -w
+
+init-git-hooks:
+	git config --local core.hooksPath .githooks/

README.md

@@ -10,10 +10,12 @@ To generate source code from the protobuf definitions contained in this project
 > **Note**: You must have [Buf CLI](https://docs.buf.build/installation) installed to run the following command.
 > 
 ```bash
-./buf.gen.yaml
+make buf-gen
 ```
 
-The command above will generate source code in the `proto/` directory.
+The command above will generate source code in the `proto/` directory. It will also configure a local git hook to check
+that files requiring auto-generation after `.proto` changes have been updated. There are some cases where that git hook
+may be overly strict. In those cases you can bypass it with `commit --no-verify`.
 
 ## Use the generated sources in OpenFGA