Added github workflow for automatic docker building on release

.github/workflows/docker.yml

@@ -0,0 +1,34 @@
+name: Docker Build and Publish Image
+on:
+  release:
+    types: [published]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    env:
+      DOCKER_IMAGE: sybila/parasim
+    steps:
+    - name: Checkout the code
+      uses: actions/checkout@v2
+    - name: Prepare
+      id: prepare
+      run: |
+        echo ::set-output name=docker_image::${DOCKER_IMAGE}
+        echo ::set-output name=release_tag::${{ github.event.release.tag_name }}
+    - name: Login to Docker Hub
+      uses: docker/login-action@v1
+      with:
+        username: ${{ secrets.DOCKER_USERNAME }}
+        password: ${{ secrets.DOCKER_PASSWORD }}
+    - name: Build Docker image
+      run: |
+        docker build \
+        --tag ${{ steps.prepare.outputs.docker_image }}:latest \
+        --tag ${{ steps.prepare.outputs.docker_image }}:${{ github.event.release.tag_name }} \
+        .
+    - name: Publish Docker image
+      # Only deploy if using master on original repo (and not for pull requests or forks)
+      if: github.repository_owner == 'sybila' && github.ref == 'refs/heads/master'
+      run: |
+        docker push --all-tags ${{ steps.prepare.outputs.docker_image }}

Dockerfile

@@ -1,4 +1,4 @@
-# Download base image ubuntu 20.04
+# Download base image ubuntu 16.04
 FROM ubuntu:16.04
 MAINTAINER Matej Trojak <xtrojak@fi.muni.cz>