added buildah image with chroot capabilities

.github/workflows/buildah.yml

@@ -0,0 +1,45 @@
+name: Build Buildah
+
+on:
+  push:
+    branches: ["*"]
+    paths: 'buildah/**'
+    tags: ["v*"]
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Generate container metadata
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: ghcr.io/obmondo/buildah
+          tags: |
+            type=semver,pattern={{version}},value=v1.32.0
+            type=ref,event=tag
+          flavor: |
+            latest=false
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build & push container image
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          file: "./buildah/Dockerfile"
+          context: .
+          labels: ${{ steps.meta.outputs.labels }}
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}

buildah/Dockerfile

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+FROM quay.io/buildah/stable:v1.32.0
+
+RUN touch /etc/subgid /etc/subuid \
+&& chmod g=u /etc/subgid /etc/subuid /etc/passwd \
+&& echo build:10000:65536 > /etc/subuid \
+&& echo build:10000:65536 > /etc/subgid
+
+# Use chroot since the default runc does not work when running rootless
+RUN echo "export BUILDAH_ISOLATION=chroot" >> /home/build/.bashrc
+
+# Use VFS since fuse does not work
+RUN mkdir -p /home/build/.config/containers \
+&& (echo '[storage]';echo 'driver = "vfs"') > /home/build/.config/containers/storage.conf
+
+# The buildah container will run as `build` user
+USER build
+WORKDIR /home/build