build: added selfhost workflow

Author: jatinlodhi2002

.github/workflows/sparrowproxy-selfhost.yml

@@ -0,0 +1,41 @@
+name: Self-host Docker Image
+on:
+  push:
+    branches: [ main ]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+env:
+  DOCKER_IMAGE_VERSION: ${{ vars.SELF_HOST_DOCKER_IMAGE_VERSION }}  
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    environment: self-host
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+
+      - name: Build and push (multi-arch)
+        run: |
+          docker buildx build \
+            --platform linux/amd64,linux/arm64 \
+            --build-arg GITHUB_TOKEN=${{ secrets.SPARROW_GITHUB_TOKEN }} \
+            -t ssparrowapi/sparrow-proxy:self-host-${DOCKER_IMAGE_VERSION} \
+            -t ssparrowapi/sparrow-proxy:latest \
+            --push .