diff --git a/owlbot-postprocessor/Dockerfile b/owlbot-postprocessor/Dockerfile
index bb0e56cc..da94207e 100644
--- a/owlbot-postprocessor/Dockerfile
+++ b/owlbot-postprocessor/Dockerfile
@@ -18,7 +18,7 @@ RUN apt-get update \
     && apt-get -y autoremove \
     && apt-get -y autoclean
 RUN mkdir /ruby-postprocessor \
-    && gem install toys:0.21.0 rexml:3.4.4
+    && gem install toys:0.21.0 rexml:3.4.4 json:2.19.2
 WORKDIR /ruby-postprocessor
 COPY lib/*.rb /ruby-postprocessor/
 COPY lib/owlbot /ruby-postprocessor/owlbot
diff --git a/owlbot-postprocessor/cloudbuild.yaml b/owlbot-postprocessor/cloudbuild.yaml
index 74db885c..94cd31f6 100644
--- a/owlbot-postprocessor/cloudbuild.yaml
+++ b/owlbot-postprocessor/cloudbuild.yaml
@@ -1,4 +1,17 @@
 steps:
+  - name: 'gcr.io/cloud-builders/gcloud'
+    entrypoint: '/bin/bash'
+    args:
+      - '-c'
+      - |
+        PREV_DIGEST=$(gcloud container images list-tags gcr.io/cloud-devrel-public-resources/owlbot-ruby --filter="tags=latest" --format="value(digest)" 2>/dev/null || true)
+        if [ ! -z "$PREV_DIGEST" ]; then
+          HEX_DIGEST=${PREV_DIGEST#sha256:}
+          echo "Previous latest digest found: $PREV_DIGEST. Adding deprecation tag..."
+          gcloud container images add-tag gcr.io/cloud-devrel-public-resources/owlbot-ruby@$PREV_DIGEST gcr.io/cloud-devrel-public-resources/owlbot-ruby:deprecated-public-image-$HEX_DIGEST --quiet
+        else
+          echo "No previous latest image found to deprecate."
+        fi
   - name: 'gcr.io/cloud-builders/docker'
     entrypoint: '/bin/bash'
     args:
@@ -6,9 +19,11 @@ steps:
       - |
         docker build \
           -t gcr.io/cloud-devrel-public-resources/owlbot-ruby:${_VERSION} \
+          -t gcr.io/cloud-devrel-public-resources/owlbot-ruby:public-image-${_VERSION} \
           -t gcr.io/cloud-devrel-public-resources/owlbot-ruby:latest \
           -f owlbot-postprocessor/Dockerfile \
           owlbot-postprocessor
 images:
   - 'gcr.io/cloud-devrel-public-resources/owlbot-ruby:${_VERSION}'
+  - 'gcr.io/cloud-devrel-public-resources/owlbot-ruby:public-image-${_VERSION}'
   - 'gcr.io/cloud-devrel-public-resources/owlbot-ruby:latest'
diff --git a/owlbot-postprocessor/test/test_owlbot_releases.rb b/owlbot-postprocessor/test/test_owlbot_releases.rb
index 908cdf77..821a7f55 100644
--- a/owlbot-postprocessor/test/test_owlbot_releases.rb
+++ b/owlbot-postprocessor/test/test_owlbot_releases.rb
@@ -42,7 +42,7 @@ def run_process cmd, output: false
     ::FileUtils.rm_rf repo_dir
     ::FileUtils.mkdir_p repo_dir
     ::Dir.chdir repo_dir do
-      run_process ["git", "init"]
+      run_process ["git", "init", "--ref-format=files"]
       run_process ["git", "commit", "--allow-empty", "-m", "commit 1"]
       run_process ["git", "commit", "--allow-empty", "-m", "commit 2"]
     end