Add docker build and publish task

Signed-off-by: trivernis <trivernis@protonmail.com>

.github/workflows/docker.yml

@@ -0,0 +1,35 @@
+name: Publish Docker image to GitHub Package Registry
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Copy Repo Files
+        uses: actions/checkout@master
+
+      - name: Publish Docker Image to GPR
+        uses: machine-learning-apps/gpr-docker-publish@master
+        id: docker
+        with:
+          IMAGE_NAME: 'user-management-server'
+          DOCKERFILE_PATH: 'Dockerfile'
+          BUILD_CONTEXT: '.'
+          CACHE: true
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Show outputs of previous step
+        run: |
+          echo "The name:tag of the Docker Image is: $VAR1"
+          echo "The docker image is hosted at $VAR2"
+        env:
+          VAR1: ${{ steps.docker.outputs.IMAGE_SHA_NAME }}
+          VAR2: ${{ steps.docker.outputs.IMAGE_URL }}