Add feature to allow force pushes when changes are just to images

Author: dhgarber

action.yml

@@ -16,6 +16,12 @@ inputs:
       deploy-pr/<environment> branch and open a PR for review
     required: false
     default: .*(staging|production).*
+  force-push-on-image-change:
+    description: |
+      When true the action will push to the <environment> branch if there 
+      only image changes detected.
+    required: false
+    default: false
   dry-run:
     description: |
       On a dry-run only the kustomize build will occur and the built branch will
@@ -175,6 +181,13 @@ runs:
         edit-mode: replace
         token: ${{ inputs.token }}
 
+    - name: Detect pure Image Changes and Force push if true
+      if: ${{ inputs.force-push-on-image-change == 'true') }
+      id: detect-image-changes
+      shell: bash
+      working-directory: ${{ inputs.working-directory }}
+      run: sha-change.sh
+
     - name: Commit to ${{ env.PUSH_BRANCH }}
       shell: bash
       working-directory: ${{ inputs.working-directory }}

sha-change.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# Get the git diff output of staged changes
+
+DIFF_OUTPUT=$(git diff  "origin/${DIFF_BRANCH}" --unified=0 | grep '^[+-]' | grep -Ev '^(---|\+\+\+|index)')
+
+echo "Diff lines:"
+echo $DIFF_OUTPUT
+
+# Check if there are any changes
+if [[ -z "$DIFF_OUTPUT" ]]; then
+    echo "No changes found in git diff."
+    exit 1
+fi
+
+# Define the allowed pattern
+ALLOWED_PATTERN='^[+-][[:space:]]*image:.*'
+
+# Check each line of the diff output
+while IFS= read -r line; do
+    if [[ ! "$line" =~ $ALLOWED_PATTERN ]]; then
+        echo "Invalid change detected: $line"
+        exit 1
+    fi
+done <<< "$DIFF_OUTPUT"
+
+echo "All changes match the allowed pattern, Forcing Deploy method to PUSH."
+echo "DEPLOY_METHOD=PUSH" >> "${GITHUB_ENV}"
+
+exit 0