Improve Docker support

.github/workflows/docker.yml

@@ -0,0 +1,27 @@
+name: Build Docker image
+on:
+  push:
+    branches:
+      - 'main'
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: nexryai/summaly-go:latest

Dockerfile

@@ -4,7 +4,8 @@ WORKDIR /app
 
 COPY . ./
 
-RUN apk add --no-cache git ca-certificates build-base \
+RUN sed -i 's#https\?://dl-cdn.alpinelinux.org/alpine#https://mirrors.xtom.com.hk/alpine#g' /etc/apk/repositories \
+ && apk add --no-cache git ca-certificates build-base \
  && go build -ldflags="-s -w" -trimpath -o summaly main.go
 
 FROM alpine:3.12
@@ -13,7 +14,8 @@ WORKDIR /app
 
 COPY --from=builder /app/summaly /app/summaly
 
-RUN apk add --no-cache ca-certificates tini \
+RUN sed -i 's#https\?://dl-cdn.alpinelinux.org/alpine#https://mirrors.xtom.com.hk/alpine#g' /etc/apk/repositories \
+ && apk add --no-cache ca-certificates tini \
  && addgroup -g 749 app \
  && adduser -u 749 -G app -D -h /app app \
  && chmod +x /app/summaly \