.github: Add workflow to build dev container

It's multi-arch, too!

Signed-off-by: Zack Cerza <[email protected]>

.github/workflows/dev_container.yml

@@ -0,0 +1,40 @@
+---
+name: dev_container
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - '*'
+  workflow_dispatch:
+  pull_request:
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Login to Quay.io
+        uses: docker/login-action@v3
+        with:
+          registry: quay.io
+          username: ${{ secrets.QUAY_USERNAME }}
+          password: ${{ secrets.QUAY_ROBOT_TOKEN }}
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        env:
+          QUAY_URI: quay.io/ceph-infra/teuthology-dev
+          QUAY_TAG: ${{ github.event_name == 'pull_request' && github.head_ref || github.ref_name }}
+        with:
+          context: .
+          file: containers/teuthology-dev/Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ env.QUAY_URI }}:${{ env.QUAY_TAG }}
+          outputs: type=image,name=target
+