Updated to use a composite action

Dockerfile

@@ -1,9 +0,0 @@
-FROM alpine:3.12
-
-LABEL maintainer="Tonye Jack <jtonye@ymail.com>"
-
-RUN apk add bash
-
-COPY entrypoint.sh /entrypoint.sh
-RUN chmod +x /entrypoint.sh
-ENTRYPOINT ["/entrypoint.sh"]

action.yml

@@ -21,19 +21,24 @@ inputs:
 
 outputs:
   base_ref_branch:
+    value: ${{ steps.branch.outputs.base_ref_branch }}
     description: 'The target branch of a pull request'
   head_ref_branch:
+    value: ${{ steps.branch.outputs.head_ref_branch }}
     description: 'The source branch of a pull request'
   ref_branch:
+    value: ${{ steps.branch.outputs.ref_branch }}
     description: 'The branch that triggered the workflow run.'
 
 runs:
-  using: 'docker'
-  image: 'Dockerfile'
-  args:
-    - ${{ inputs.base_ref }}
-    - ${{ inputs.head_ref }}
-    - ${{ inputs.ref }}
+  using: "composite"
+  steps:
+    - id: branch
+      run: |
+        echo "::set-output name=base_ref_branch::${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\//}"
+      shell: bash
 branding:
   icon: git-branch
   color: white

entrypoint.sh

@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-
-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\//}"