add github action for build multiple cpu arch images

.github/workflows/build.yaml

@@ -0,0 +1,50 @@
+---
+name: Build nix images
+
+on:
+  push:
+    branches: [master, release-*]
+  release:
+    branches: [master, release-*]
+
+env:
+  IMAGE_REPO: "muzi502"
+  IMAGE_NAME: "nixos-nix"
+  IMAGE_REGISTRY: "ghcr.io"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Define image tags by current git repo tag and branch
+        shell: bash
+        run: |
+          git describe --tags --always | sed 's/^/IMAGE_TAG=/' >> $GITHUB_ENV
+          git branch --show-current | sed 's/master/latest/;s/release-//;s/^/IMAGE_TAG_BY_BRANCH=/' >> $GITHUB_ENV
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Log in to GitHub Docker Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ${{ env.IMAGE_REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build image
+        run: |
+          docker buildx build \
+                 --pull \
+                 --push \
+                 --platform="linux/amd64,linux/arm64" \
+                 -t ${IMAGE_REGISTRY}/${IMAGE_REPO}/${IMAGE_NAME}:${IMAGE_TAG} \
+                 -t ${IMAGE_REGISTRY}/${IMAGE_REPO}/${IMAGE_NAME}:${IMAGE_TAG_BY_BRANCH} \
+                 -f Dockerfile \
+                 .

Dockerfile

@@ -4,7 +4,8 @@ FROM alpine
 
 # Enable HTTPS support in wget and set nsswitch.conf to make resolution work within containers
 RUN apk add --no-cache --update openssl \
-  && echo hosts: files dns > /etc/nsswitch.conf
+  && echo hosts: files dns > /etc/nsswitch.conf \
+  && rm -rf /var/cache/apk/*
 
 # Download Nix and install it into the system.
 ARG NIX_VERSION=2.3.12
@@ -14,10 +15,11 @@ RUN wget https://nixos.org/releases/nix/nix-${NIX_VERSION}/nix-${NIX_VERSION}-$(
   && for i in $(seq 1 30); do adduser -S -D -h /var/empty -g "Nix build user $i" -u $((30000 + i)) -G nixbld nixbld$i ; done \
   && mkdir -m 0755 /etc/nix \
   && echo 'sandbox = false' > /etc/nix/nix.conf \
+  && echo 'use-sqlite-wal = false' >> /etc/nix/nix.conf \
+  && echo 'filter-syscalls = false' >> /etc/nix/nix.conf \
   && mkdir -m 0755 /nix && USER=root sh nix-${NIX_VERSION}-$(uname -m)-linux/install \
   && ln -s /nix/var/nix/profiles/default/etc/profile.d/nix.sh /etc/profile.d/ \
   && rm -r /nix-${NIX_VERSION}-$(uname -m)-linux* \
-  && rm -rf /var/cache/apk/* \
   && /nix/var/nix/profiles/default/bin/nix-collect-garbage --delete-old \
   && /nix/var/nix/profiles/default/bin/nix-store --optimise \
   && /nix/var/nix/profiles/default/bin/nix-store --verify --check-contents