Add workflow to publish image

.github/workflows/build.yml

@@ -1,6 +1,6 @@
 name: Lint & build
 
-on: [push, pull_request]
+on: [pull_request]
 
 jobs:
     build:

.github/workflows/publish-image.yml

@@ -0,0 +1,42 @@
+name: Publish Docker image
+
+on:
+    push:
+        branches: master
+
+jobs:
+    main:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Set up Buildx
+              uses: docker/setup-buildx-action@v1
+              
+            - name: Cache Docker layers
+              uses: actions/cache@v2
+              with:
+                path: /tmp/.buildx-cache
+                key: ${{ runner.os }}-buildx-${{ github.sha }}
+                restore-keys: |
+                  ${{ runner.os }}-buildx-
+                  
+            - name: Login to DockerHub
+              uses: docker/login-action@v1
+              with:
+                username: ${{ secrets.DOCKERHUB_USERNAME }}
+                password: ${{ secrets.DOCKERHUB_TOKEN }}
+                
+            - name: Build and push
+              id: docker_build
+              uses: docker/build-push-action@v2
+              with:
+                push: true
+                tags: codetheweb/muse:latest
+                platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/ppc64le,linux/s390x
+                
+            - name: Update Docker Hub description
+              uses: peter-evans/dockerhub-description@v2.1.0
+              env:
+                DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+                DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
+                DOCKERHUB_REPOSITORY: peterevans/dockerhub-description
+