use manifest-tool to create multi-arch image

.github/workflows/tip.yaml

@@ -49,3 +49,24 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Docker push
         run: nix develop --command skopeo copy "docker-archive:result" "docker://ghcr.io/connet-dev/connet:latest-arm64"
+
+  docker-multiarch:
+    name: Tag multi-arch
+    runs-on: ubuntu-latest
+    needs: [docker-build-x86, docker-build-arm]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - name: Docker login
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Docker tag
+        run: nix develop --command manifest-tool push from-args --platforms linux/amd64,linux/arm64 --template connet-dev/connet:latest-ARCHVARIANT --target connet-dev/connet:latest
+

flake.nix

@@ -6,7 +6,7 @@
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { nixpkgs, flake-utils, ... }:
     {
       nixosModules.default = ./nix/client-module.nix;
       nixosModules.server = ./nix/server-module.nix;
@@ -30,6 +30,7 @@
             gopls
             golangci-lint
             fd
+            manifest-tool
             protobuf
             protoc-gen-go
             process-compose