feat: add oci container definitions build with nix

.github/workflows/release.yaml

@@ -7,6 +7,7 @@ on:
 
 permissions:
   contents: write
+  packages: write
 
 jobs:
   release-linux:
@@ -48,3 +49,78 @@ jobs:
           args: release --clean --config .goreleaser-darwin.yaml --skip=validate
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  release-containers:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        variant: [alpine, debian, ubuntu, scratch]
+        include:
+          - variant: alpine
+            is_default: true
+          - variant: debian
+            is_default: false
+          - variant: ubuntu
+            is_default: false
+          - variant: scratch
+            is_default: false
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: DeterminateSystems/nix-installer-action@v17
+
+      - uses: nix-community/cache-nix-action@v6
+        with:
+          primary-key: nix-${{ runner.os }}-${{ hashFiles('flake.lock') }}
+          restore-prefixes-first-match: nix-${{ runner.os }}-
+
+      - name: login to ghcr
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: build container
+        run: nix build ".#snitch-${{ matrix.variant }}" --print-out-paths
+
+      - name: load and push container
+        env:
+          VERSION: ${{ github.ref_name }}
+          REPO: ghcr.io/${{ github.repository_owner }}/snitch
+          VARIANT: ${{ matrix.variant }}
+          IS_DEFAULT: ${{ matrix.is_default }}
+        run: |
+          VERSION="${VERSION#v}"
+
+          docker load < result
+
+          IMAGE_TAG=$(docker images --format '{{.Repository}}:{{.Tag}}' | grep "snitch:.*-${VARIANT}" | head -1)
+
+          if [ -z "$IMAGE_TAG" ]; then
+            echo "error: could not find loaded image for ${VARIANT}"
+            exit 1
+          fi
+
+          docker tag "$IMAGE_TAG" "${REPO}:${VERSION}-${VARIANT}"
+          docker tag "$IMAGE_TAG" "${REPO}:latest-${VARIANT}"
+          docker push "${REPO}:${VERSION}-${VARIANT}"
+          docker push "${REPO}:latest-${VARIANT}"
+
+          if [ "$IS_DEFAULT" = "true" ]; then
+            docker tag "$IMAGE_TAG" "${REPO}:${VERSION}"
+            docker tag "$IMAGE_TAG" "${REPO}:latest"
+            docker push "${REPO}:${VERSION}"
+            docker push "${REPO}:latest"
+          fi
+
+      - name: summary
+        env:
+          VERSION: ${{ github.ref_name }}
+          REPO: ghcr.io/${{ github.repository_owner }}/snitch
+          VARIANT: ${{ matrix.variant }}
+        run: |
+          VERSION="${VERSION#v}"
+          echo "pushed ${REPO}:${VERSION}-${VARIANT}" >> $GITHUB_STEP_SUMMARY

README.md

@@ -107,6 +107,47 @@ curl -sSL https://raw.githubusercontent.com/karol-broda/snitch/master/install.sh
 
 > **macos:** the install script automatically removes the quarantine attribute (`com.apple.quarantine`) from the binary to allow it to run without gatekeeper warnings. to disable this, set `KEEP_QUARANTINE=1`.
 
+### docker
+
+pre-built oci images available from github container registry:
+
+```bash
+# pull from ghcr.io
+docker pull ghcr.io/karol-broda/snitch:latest          # alpine (default)
+docker pull ghcr.io/karol-broda/snitch:latest-alpine   # alpine (~17MB)
+docker pull ghcr.io/karol-broda/snitch:latest-scratch  # minimal, binary only (~9MB)
+docker pull ghcr.io/karol-broda/snitch:latest-debian   # debian trixie
+docker pull ghcr.io/karol-broda/snitch:latest-ubuntu   # ubuntu 24.04
+
+# or use a specific version
+docker pull ghcr.io/karol-broda/snitch:0.2.0-alpine
+```
+
+alternatively, build locally via nix flake:
+
+```bash
+nix build github:karol-broda/snitch#snitch-alpine
+docker load < result
+```
+
+**running the container:**
+
+```bash
+# basic usage - sees host sockets but not process names
+docker run --rm --net=host snitch:latest ls
+
+# full info - includes PID, process name, user
+docker run --rm --net=host --pid=host --cap-add=SYS_PTRACE snitch:latest ls
+```
+
+| flag | purpose |
+|------|---------|
+| `--net=host` | share host network namespace (required to see host connections) |
+| `--pid=host` | share host pid namespace (needed for process info) |
+| `--cap-add=SYS_PTRACE` | read process details from `/proc/<pid>` |
+
+> **note:** `CAP_NET_ADMIN` and `CAP_NET_RAW` are not required. snitch reads from `/proc/net/*` which doesn't need special network capabilities.
+
 ### binary
 
 download from [releases](https://github.com/karol-broda/snitch/releases):

flake.nix

@@ -80,11 +80,18 @@
     in
     {
       packages = eachSystem (system:
-        let pkgs = pkgsFor system; in
-        {
-          default = mkSnitch pkgs;
+        let
+          pkgs = pkgsFor system;
           snitch = mkSnitch pkgs;
-        }
+          # containers only available on linux
+          containers = if pkgs.stdenv.isLinux
+            then import ./nix/containers.nix { inherit pkgs snitch; }
+            else { };
+        in
+        {
+          default = snitch;
+          inherit snitch;
+        } // containers
       );
 
       devShells = eachSystem (system:
@@ -94,7 +101,7 @@
         in
         {
           default = pkgs.mkShell {
-            packages = [ go pkgs.git pkgs.vhs ];
+            packages = [ go pkgs.git pkgs.vhs pkgs.nix-prefetch-docker ];
             env.GOTOOLCHAIN = "local";
             shellHook = ''
               echo "go toolchain: $(go version)"

nix/containers.nix

@@ -0,0 +1,121 @@
+# oci container definitions for snitch
+# builds containers based on different base images: alpine, debian trixie, ubuntu
+#
+# base images are pinned by imageDigest (immutable content hash), not by tag.
+# even if the upstream tag gets a new image, builds remain reproducible.
+#
+# to update base image hashes, run:
+#   nix-prefetch-docker --image-name alpine --image-tag 3.21
+#   nix-prefetch-docker --image-name debian --image-tag trixie-slim
+#   nix-prefetch-docker --image-name ubuntu --image-tag 24.04
+#
+# this outputs both imageDigest and sha256 values needed below
+{ pkgs, snitch }:
+let
+  commonConfig = {
+    name = "snitch";
+    tag = snitch.version;
+    config = {
+      Entrypoint = [ "${snitch}/bin/snitch" ];
+      Env = [ "PATH=/bin" ];
+      Labels = {
+        "org.opencontainers.image.title" = "snitch";
+        "org.opencontainers.image.description" = "a friendlier ss/netstat for humans";
+        "org.opencontainers.image.source" = "https://github.com/karol-broda/snitch";
+        "org.opencontainers.image.licenses" = "MIT";
+      };
+    };
+  };
+
+  # alpine-based container
+  alpine = pkgs.dockerTools.pullImage {
+    imageName = "alpine";
+    imageDigest = "sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c";
+    sha256 = "sha256-WNbRh44zld3lZtKARhdeWFte9JKgD2bgCuKzETWgGr8=";
+    finalImageName = "alpine";
+    finalImageTag = "3.21";
+  };
+
+  # debian trixie (testing) based container
+  debianTrixie = pkgs.dockerTools.pullImage {
+    imageName = "debian";
+    imageDigest = "sha256:e711a7b30ec1261130d0a121050b4ed81d7fb28aeabcf4ea0c7876d4e9f5aca2";
+    sha256 = "sha256-W/9A7aaPXFCmmg+NTSrFYL+QylsAgfnvkLldyI18tqU=";
+    finalImageName = "debian";
+    finalImageTag = "trixie-slim";
+  };
+
+  # ubuntu based container
+  ubuntu = pkgs.dockerTools.pullImage {
+    imageName = "ubuntu";
+    imageDigest = "sha256:c35e29c9450151419d9448b0fd75374fec4fff364a27f176fb458d472dfc9e54";
+    sha256 = "sha256-0j8xM+mECrBBHv7ZqofiRaeSoOXFBtLYjgnKivQztS0=";
+    finalImageName = "ubuntu";
+    finalImageTag = "24.04";
+  };
+
+  # scratch container (minimal, just the snitch binary)
+  scratch = pkgs.dockerTools.buildImage {
+    name = "snitch";
+    tag = "${snitch.version}-scratch";
+    copyToRoot = pkgs.buildEnv {
+      name = "snitch-root";
+      paths = [ snitch ];
+      pathsToLink = [ "/bin" ];
+    };
+    config = commonConfig.config;
+  };
+
+in
+{
+  snitch-alpine = pkgs.dockerTools.buildImage {
+    name = "snitch";
+    tag = "${snitch.version}-alpine";
+    fromImage = alpine;
+    copyToRoot = pkgs.buildEnv {
+      name = "snitch-root";
+      paths = [ snitch ];
+      pathsToLink = [ "/bin" ];
+    };
+    config = commonConfig.config;
+  };
+
+  snitch-debian = pkgs.dockerTools.buildImage {
+    name = "snitch";
+    tag = "${snitch.version}-debian";
+    fromImage = debianTrixie;
+    copyToRoot = pkgs.buildEnv {
+      name = "snitch-root";
+      paths = [ snitch ];
+      pathsToLink = [ "/bin" ];
+    };
+    config = commonConfig.config;
+  };
+
+  snitch-ubuntu = pkgs.dockerTools.buildImage {
+    name = "snitch";
+    tag = "${snitch.version}-ubuntu";
+    fromImage = ubuntu;
+    copyToRoot = pkgs.buildEnv {
+      name = "snitch-root";
+      paths = [ snitch ];
+      pathsToLink = [ "/bin" ];
+    };
+    config = commonConfig.config;
+  };
+
+  snitch-scratch = scratch;
+
+  oci-default = pkgs.dockerTools.buildImage {
+    name = "snitch";
+    tag = snitch.version;
+    fromImage = alpine;
+    copyToRoot = pkgs.buildEnv {
+      name = "snitch-root";
+      paths = [ snitch ];
+      pathsToLink = [ "/bin" ];
+    };
+    config = commonConfig.config;
+  };
+}
+