Added GitHub Actions and Workflow

Fixes #7

.github/actions/build-image/action.yml

@@ -0,0 +1,21 @@
+name: 'Build And Publish Image'
+description: 'Builds and publishes image'
+inputs:
+  version:
+    description: 'image tag'
+    required: true
+  dockerhub-username:
+    description: 'dockerhub username'
+    required: true
+  dockerhub-password:
+    description: 'dockerhub password'
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Build and Push image
+      uses: docker/build-push-action@v2
+      with:
+        context: .
+        push: true
+        tags: springcloud/baseimage:${{ inputs.version }}

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: CI
+
+on:
+  workflow_dispatch:
+  push:
+    paths-ignore:
+      - '.github/**'
+
+jobs:
+  build:
+    if: github.repository_owner == 'spring-cloud'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Determine version
+        run: |
+          echo baseimage_version=$(cat version.txt) >> $GITHUB_ENV
+      - name: Build and Publish Images
+        uses: ./.github/actions/build-images
+        with:
+          version: ${{ env.baseimage_version }}
+          dockerhub-username: ${{ secrets.DOCKERHUB_USERNAME }}
+          dockerhub-password: ${{ secrets.DOCKERHUB_TOKEN }}