switch to use inputs.

action.yml

@@ -6,6 +6,18 @@ inputs:
     description: 'GITHUB_TOKEN or a Repo scoped PAT'
     required: true
     default: ${{ github.token }}
+  base_ref:
+    description: 'The target branch of a pull request'
+    default: ${{ github.base_ref }}
+    required: false
+  head_ref:
+    description: 'The source branch of a pull request'
+    default: ${{ github.head_ref }}
+    required: false
+  ref:
+    description: 'The branch that triggered the workflow run.'
+    default: ${{ github.ref }}
+    required: false
 
 outputs:
   base_ref_branch:
@@ -18,6 +30,10 @@ outputs:
 runs:
   using: 'docker'
   image: 'Dockerfile'
+  args:
+    - ${{ inputs.base_ref }}
+    - ${{ inputs.head_ref }}
+    - ${{ inputs.ref }}
 branding:
   icon: git-branch
   color: white

entrypoint.sh

@@ -2,6 +2,6 @@
 
 set -e
 
-echo "::set-output name=base_ref_branch::${INPUT_BASE_REF/refs\/heads\//}"
-echo "::set-output name=head_ref_branch::${INPUT_HEAD_REF/refs\/heads\//}"
-echo "::set-output name=ref_branch::${INPUT_REF/refs\/heads\//}"
+echo "::set-output name=base_ref_branch::${0/refs\/heads\//}"
+echo "::set-output name=head_ref_branch::${1/refs\/heads\//}"
+echo "::set-output name=ref_branch::${2/refs\/heads\//}"