feat: Use a rootless hardened docker image

.dockerignore

@@ -4,3 +4,4 @@ backend/.env
 frontend/node_modules
 frontend/dist
 frontend/.tanstack
+*.exe

.github/workflows/release.yml

@@ -50,11 +50,23 @@ jobs:
       matrix:
         include:
           - name: hub
+            base_image: gcr.io/distroless/base-nossl-debian13:nonroot
           - name: agent
+            base_image: gcr.io/distroless/base-nossl-debian13:latest
     steps:
       - name: Checkout
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
+      - name: Install cosign
+        uses: sigstore/cosign-installer@cad07c2e89fa2edd6e2d7bab4c1aa38e53f76003 # v4.1.1
+
+      - name: Verify distroless base image signature
+        run: |
+          cosign verify \
+            ${{ matrix.base_image }} \
+            --certificate-oidc-issuer https://accounts.google.com \
+            --certificate-identity keyless@distroless.iam.gserviceaccount.com
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@ce360397dd3f832beb865e1373c09c0e9f86d70a # v4.0.0
 
@@ -82,6 +94,7 @@ jobs:
             type=raw,value=main,enable=${{ github.event_name == 'workflow_dispatch' }}
 
       - name: Build and push ${{ matrix.name }} image
+        id: build
         uses: docker/build-push-action@bcafcacb16a39f128d818304e6c9c0c18556b85f # v7.1.0
         with:
           context: .
@@ -98,3 +111,8 @@ jobs:
           cache-to: type=gha,mode=max
           provenance: true
           sbom: true
+
+      - name: Sign ${{ matrix.name }} image
+        run: |
+          cosign sign --yes \
+            ${{ env.IMAGE_PREFIX }}/${{ matrix.name }}@${{ steps.build.outputs.digest }}

agent.Dockerfile

@@ -1,13 +1,11 @@
 FROM bufbuild/buf:1.68 AS buf
 
-FROM golang:1.26-alpine AS builder
+FROM golang:1.26-trixie AS builder
 
 ARG VERSION=dev
 ARG COMMIT=none
 ARG BUILD_DATE=unknown
 
-RUN apk add --no-cache gcc musl-dev
-
 WORKDIR /src
 COPY backend/go.mod backend/go.sum ./
 RUN go mod download
@@ -26,7 +24,9 @@ RUN CGO_ENABLED=1 go build \
     -X github.com/OrcaCD/orca-cd/internal/version.BuildDate=${BUILD_DATE}" \
     -o /bin/agent ./cmd/agent
 
-FROM alpine:3.23
+# Not using nonroot variant as agent has access to the docker socket which is basically root access
+# Changing to nonroot user would complicate setup for users with minimal security benefits
+FROM gcr.io/distroless/base-nossl-debian13:latest
 
 WORKDIR /app
 

backend/internal/hub/data_dir.go

@@ -0,0 +1,40 @@
+package hub
+
+import (
+	"fmt"
+	"os"
+)
+
+func initDataDir() error {
+	if err := os.MkdirAll("data", 0750); err != nil {
+		return err
+	}
+	return checkDataDirWritable()
+}
+
+func checkDataDirWritable() error {
+	return checkWritable("data")
+}
+
+func checkWritable(dir string) error {
+	f, err := os.CreateTemp(dir, ".write-check-*")
+	if err == nil {
+		err = f.Close()
+		if err != nil {
+			return err
+		}
+		err = os.Remove(f.Name())
+		if err != nil {
+			return err
+		}
+		return nil
+	}
+	if !os.IsPermission(err) {
+		return err
+	}
+	uid := os.Getuid()
+	return fmt.Errorf(
+		"directory is not writable, run: sudo chown -R %d:%d ./data",
+		uid, os.Getgid(),
+	)
+}

backend/internal/hub/data_dir_test.go

@@ -0,0 +1,23 @@
+package hub
+
+import (
+	"os"
+	"testing"
+)
+
+func TestCheckWritable_WritableDir(t *testing.T) {
+	dir := t.TempDir()
+	if err := checkWritable(dir); err != nil {
+		t.Fatalf("expected nil for writable directory, got %v", err)
+	}
+}
+
+func TestCheckWritable_NonExistentDir(t *testing.T) {
+	err := checkWritable(t.TempDir() + "/does-not-exist")
+	if err == nil {
+		t.Fatal("expected error for non-existent directory, got nil")
+	}
+	if os.IsPermission(err) {
+		t.Errorf("expected a non-permission error for missing directory, got: %v", err)
+	}
+}

backend/internal/hub/data_dir_unix_test.go

@@ -0,0 +1,30 @@
+//go:build !windows
+
+package hub
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestCheckWritable_ReadOnlyDir(t *testing.T) {
+	if os.Getuid() == 0 {
+		t.Skip("skipping: chmod has no effect when running as root")
+	}
+	dir := t.TempDir()
+	if err := os.Chmod(dir, 0o444); err != nil {
+		t.Fatalf("chmod: %v", err)
+	}
+	// Restore before t.TempDir cleanup so the directory can be removed.
+	// t.Cleanup runs in LIFO order, so this runs before the TempDir cleanup.
+	t.Cleanup(func() { os.Chmod(dir, 0o750) })
+
+	err := checkWritable(dir)
+	if err == nil {
+		t.Fatal("expected error for read-only directory, got nil")
+	}
+	if !strings.Contains(err.Error(), "not writable") {
+		t.Errorf("error %q does not contain expected message", err)
+	}
+}

backend/internal/hub/server.go

@@ -111,6 +111,11 @@ func Run(cfg Config) error {
 		return err
 	}
 
+	if err := initDataDir(); err != nil {
+		Log.Error().Err(err).Msg("failed to initialize data directory")
+		return err
+	}
+
 	dbLogger := Log.With().Str("component", "gorm").Logger()
 	err := db.Connect(dbLogger, cfg.LogLevel, cfg.Demo)
 	if err != nil {

hub.Dockerfile

@@ -12,14 +12,12 @@ RUN npm run build
 
 FROM bufbuild/buf:1.68 AS buf
 
-FROM golang:1.26-alpine AS builder
+FROM golang:1.26-trixie AS builder
 
 ARG VERSION=dev
 ARG COMMIT=none
 ARG BUILD_DATE=unknown
 
-RUN apk add --no-cache gcc musl-dev sqlite-dev
-
 WORKDIR /src
 COPY backend/go.mod backend/go.sum ./
 RUN go mod download
@@ -33,19 +31,17 @@ RUN buf generate
 
 RUN CGO_ENABLED=1 go build \
     -ldflags "-s -w \
-      -X github.com/OrcaCD/orca-cd/internal/version.Version=${VERSION} \
-      -X github.com/OrcaCD/orca-cd/internal/version.Commit=${COMMIT} \
-      -X github.com/OrcaCD/orca-cd/internal/version.BuildDate=${BUILD_DATE}" \
+    -X github.com/OrcaCD/orca-cd/internal/version.Version=${VERSION} \
+    -X github.com/OrcaCD/orca-cd/internal/version.Commit=${COMMIT} \
+    -X github.com/OrcaCD/orca-cd/internal/version.BuildDate=${BUILD_DATE}" \
     -o /bin/hub ./cmd/hub
 
-FROM alpine:3.23
+FROM gcr.io/distroless/base-nossl-debian13:nonroot
 
 WORKDIR /app
 
-RUN apk add --no-cache ca-certificates sqlite-libs
-
-COPY --from=builder /bin/hub /app/hub
-COPY --from=frontend-builder /app/frontend/dist ./frontend/dist
+COPY --from=builder --chown=nonroot:nonroot /bin/hub /app/hub
+COPY --from=frontend-builder --chown=nonroot:nonroot /app/frontend/dist ./frontend/dist
 
 EXPOSE 8080