infer image tag from config yaml

.github/workflows/hermetic_library_generation.yaml

@@ -33,7 +33,6 @@ jobs:
         [ -z "$(git config user.name)" ] && git config --global user.name "cloud-java-bot"
         bash generation/hermetic_library_generation.sh \
           --target_branch ${{ github.base_ref }} \
-          --current_branch ${{ github.head_ref }} \
-          --image_tag $(cat generation_config.yaml | yq .gapic_generator_version)
+          --current_branch ${{ github.head_ref }}
       env:
         GH_TOKEN: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}

generation/hermetic_library_generation.sh

@@ -21,7 +21,6 @@ set -e
 # The parameters of this script is:
 # 1. target_branch, the branch into which the pull request is merged.
 # 2. current_branch, the branch with which the pull request is associated.
-# 3. image_tag, the tag of gcr.io/cloud-devrel-public-resources/java-library-generation.
 # 3. [optional] generation_config, the path to the generation configuration,
 # the default value is generation_config.yaml in the repository root.
 while [[ $# -gt 0 ]]; do
@@ -35,10 +34,6 @@ case "${key}" in
     current_branch="$2"
     shift
     ;;
-  --image_tag)
-    image_tag="$2"
-    shift
-    ;;
   --generation_config)
     generation_config="$2"
     shift
@@ -61,14 +56,9 @@ if [ -z "${current_branch}" ]; then
   exit 1
 fi
 
-if [ -z "${image_tag}" ]; then
-  echo "missing required argument --image_tag"
-  exit 1
-fi
-
 if [ -z "${generation_config}" ]; then
   generation_config=generation_config.yaml
-  echo "Use default generation config: ${generation_config}"
+  echo "Using default generation config: ${generation_config}"
 fi
 
 workspace_name="/workspace"
@@ -88,6 +78,9 @@ fi
 git show "${target_branch}":"${generation_config}" > "${baseline_generation_config}"
 config_diff=$(diff "${generation_config}" "${baseline_generation_config}" || true)
 
+# parse image tag from the generation configuration.
+image_tag=$(grep "gapic_generator_version" "${generation_config}" | cut -d ':' -f 2 | xargs)
+
 # run hermetic code generation docker image.
 docker run \
   --rm \