docker workflow.

.github/workflows/docker.yml

@@ -0,0 +1,58 @@
+name: Docker
+
+on:
+  push:
+
+jobs:
+  # Set variables that will be available to all builds.
+  env_vars:
+    runs-on: ubuntu-22.04
+    outputs:
+      release_version: ${{ steps.release_version.outputs.release_version }}
+      binary: ${{ steps.binary.outputs.binary }}
+    steps:
+      - id: release_version
+        run: |
+          RELEASE_VERSION=$(echo ${{ github.ref_name }} | sed -e 's/^[vt]//')
+          echo "release_version=${RELEASE_VERSION}" >> $GITHUB_OUTPUT
+      - id: binary
+        run: |
+          BINARY=$(basename ${{ github.repository }})
+          echo "binary=${BINARY}" >> $GITHUB_OUTPUT
+
+  # Build.
+  build:
+    runs-on: ubuntu-22.04
+    needs: [env_vars]
+    steps:
+      - name: Check out repository into the Go module directory
+        uses: actions/checkout@v3
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64/v8,linux/arm/v7
+          push: true
+          tags: wealdtech/ethdo:latest
+
+      - name: build and push on release
+        uses: docker/build-push-action@v4
+        if: ${{ github.event.release.tag_name != '' }}
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64/v8,linux/arm/v7
+          push: true
+          tags: wealdtech/ethdo:${{ github.event.release.tag_name }}