rules_nextjs

Bazel rules for Next.js. Runs next build as a hermetic Bazel action with the workspace's deps as explicit inputs and the .next/ tree as the declared output.

• rule: next_build — see docs/defs.md.
• rule/macro: next_standalone — turn an output = "standalone" build into a bazel run-able server and a deployable bundle for pkg_tar/oci_image.
• provider: NextBuildInfo — wraps the .next output tree so future rules (deploy targets, oci_image wrappers, doc-site extractors) can consume builds programmatically.

Install

Add the registry to your .bazelrc:

common --registry=https://raw.githubusercontent.com/fastverk/bazel-registry/main/
common --registry=https://bcr.bazel.build/

In your MODULE.bazel:

bazel_dep(name = "rules_nextjs", version = "0.1.0")

You'll also need aspect_rules_js (or equivalent) to expose next as a js_binary-compatible target — this rule consumes the CLI via next_bin, doesn't bring its own.

Quick start

load("@npm//:my-app/next/package_json.bzl", next_bin_gen = "bin")
load("@rules_nextjs//next:defs.bzl", "next_build")

# Real js_binary wrapping node_modules/next/dist/bin/next. The rule needs
# an executable target — `:node_modules/next/dir` is a directory and
# cannot be exec'd directly. aspect_rules_js generates `bin.next_binary`
# for any npm package that declares a bin in its package.json.
next_bin_gen.next_binary(name = "next_cli")

next_build(
    name = "build",
    srcs = glob(["src/**/*", "public/**/*"]) + [
        "next.config.ts",
        "tsconfig.json",
    ],
    deps = [
        "//packages/some-lib:lib",
        ":node_modules/next",
        ":node_modules/react",
        ":node_modules/react-dom",
    ],
    data = [
        # Runtime assets dropped into public/ before the build.
        "//db/migrations:bundle",
    ],
    next_bin = ":next_cli",
)

bazel build //:build produces bazel-bin/build.out/ containing the full .next/ tree (standalone/, static/, trace files).

Standalone: runnable server + deployable bundle

next build's output: 'standalone' emits the self-contained server (.next/standalone) and the hashed client assets (.next/static) as siblings — neither runs on its own. next_standalone re-stitches them into one tree (matching the hand-written Dockerfile COPY layout) and exposes it two ways:

load("@rules_nextjs//next:defs.bzl", "next_build", "next_standalone")

next_build(
    name = "build",
    # ... as above ...
    output = "standalone",  # the default; static/vercel get no runnable
    next_bin = ":next_cli",
)

next_standalone(
    name = "app",
    build = ":build",
    next_bin = ":next_cli",  # borrowed for the hermetic Node
)

• bazel run //:app — serve the app on the hermetic Node (honors PORT / HOSTNAME).

• //:app.bundle — a TreeArtifact ready for an image:

  load("@rules_pkg//pkg:tar.bzl", "pkg_tar")
  load("@rules_oci//oci:defs.bzl", "oci_image")
  
  pkg_tar(name = "app_layer", srcs = ["//:app.bundle"], package_dir = "/app")
  oci_image(
      name = "image",
      base = "@distroless_nodejs",
      tars = [":app_layer"],
      workdir = "/app",
      # The bundle drops a fixed-name entry shim at its root (it discovers the
      # nested server.js for you), so the cmd never changes per app:
      cmd = ["__next_standalone_server.cjs"],
  )

The standalone server resolves /_next/static/* relative to the cwd, so the runnable and the entry shim both cd to the bundle root, where .next/static is re-stitched.

next_build repairs the standalone node_modules so dynamic runtime requires (e.g. next's require-hook → styled-jsx) resolve — without it the deref'd standalone crashes on boot. The trade-off is a heavier node_modules than a pnpm-built standalone; see the CHANGELOG 0.3.0 note.

Hermeticity

The rule forces three Next.js env vars:

• NEXT_TELEMETRY_DISABLED=1
• NEXT_PRIVATE_STANDALONE=1
• NODE_ENV=production

The rest of the hermeticity scrub lives in each app's next.config.ts — rules_nextjs deliberately doesn't try to patch from the outside. Consumer-side checklist:

Bring under control	How
Font CDN fetches	Vendor under public/fonts/ or use next/font/local; next/font/google reaches fonts.googleapis.com at build time
Image optimizer pre-fetches	images: { unoptimized: true } or explicit remotePatterns
Build-time network from instrumentation	Audit instrumentation*.ts for module-init side effects
Next version	Pin via root package.json catalog

Validate the scrub by building with --network none after the migration lands.

Compatibility

• Bazel: 7.4+, bzlmod required.
• Next.js: 14+ tested. Earlier versions may work — next build <app-dir> and the env-var contract have been stable.
• Workspace shape: assumes aspect_rules_js-style npm linking (:node_modules/next/dir).

Contributing

Reference docs (docs/defs.md) are stardoc-generated. After editing rule docstrings:

bazel run //docs:update

CI gates this via bazel test //docs/....

License

MIT.