How builds work

Services with a GitHub source are built by the Fjordrun builder. It clones the commit, decides how to build it, and produces a container image. Services from a Docker image or a template skip the build.

Decision order

The builder looks at the service's root directory and takes the first match:

1. A Dockerfile — Dockerfile, dockerfile or Containerfile, or the path set in Settings → Build → Dockerfile path. A repository Dockerfile always wins, whatever else is in the repository. See Dockerfiles.
2. Nixpacks selected — if you set the builder to Nixpacks in the service settings.
3. A Node.js project (package.json) — the builder detects the framework and generates a multi-stage Dockerfile for it (below).
4. A plain static site — an index.html at the root, or only in dist/, public/, build/, site/, www/, out/ or _site/ — served by nginx.
5. Anything else (Python, Go, Ruby, PHP, ...) — built with Nixpacks.

The build log starts with the decision, and the deployment stores it as its build plan:

Fjordrun builder: detected Vite + React (static) · npm · Node 22
  install  npm ci
  build    npm run build
  serve    dist/ with nginx   (port $PORT)

Node.js frameworks

For a Node.js project, the builder reads package.json (dependencies, scripts, engines), the lockfile and the framework's config file, and picks one of three ways to run it.

Static sites, served by nginx

These are built with your build script and the output is served by nginx (non-root nginx-unprivileged) on $PORT, with gzip, long caching for content-hashed assets, no-cache for HTML, and a /healthz endpoint. Single-page apps get a fallback to index.html for client-side routes; multi-page sites return real 404s (using your 404.html if there is one).

Framework	Detected when	Output served
Vite (React, Vue, Svelte, Solid, Preact, Lit)	vite with a vite.config.*, an index.html or a vite build script	dist (or build.outDir)
Create React App	react-scripts	build
Vue CLI	@vue/cli-service	dist
Angular (no SSR)	@angular/core	outputPath from angular.json (dist/<project>/browser)
Astro (static)	astro without a server adapter	dist (or outDir)
Nuxt (static)	ssr: false, a static preset, or nuxt generate as the build script	.output/public
Next.js (export)	output: 'export' in next.config.*	out
SvelteKit (static)	@sveltejs/adapter-static	build (or pages)
React Router 7 (SPA)	ssr: false in react-router.config.*	build/client
Gatsby	gatsby	public
Docusaurus	@docusaurus/core	build
VitePress	vitepress	<src>/.vitepress/dist
Eleventy	@11ty/eleventy	_site (or --output)

If the expected folder is missing after the build, the builder also tries dist, build, out, .output/public, public, _site, site and www.

Server-side rendering and servers, run with Node.js

These run their own server as the unprivileged node user:

Framework	Runs
Nuxt (SSR)	node .output/server/index.mjs
Next.js with output: 'standalone'	node server.js from the standalone output
Next.js (default)	next start -H 0.0.0.0 -p $PORT
Astro with @astrojs/node (standalone)	node ./dist/server/entry.mjs
Astro with @astrojs/node (middleware)	your start script
SvelteKit with @sveltejs/adapter-node	node build
Angular with @angular/ssr	node dist/<project>/server/server.mjs
Remix / React Router 7 (SSR)	your start script, else remix-serve / react-router-serve
NestJS	start:prod script, else node dist/main
Express, Fastify, Koa, Hono, hapi, others	your start script, else node + main, server.js, index.js, app.js...

Development dependencies are pruned after the build when the run command does not need them.

Unsupported adapters

Some framework adapters produce output that only runs on one hosting provider. The build stops with a clear message instead of deploying something that cannot start:

• Astro with @astrojs/vercel, @astrojs/netlify, @astrojs/cloudflare or @astrojs/deno → use @astrojs/node (mode: 'standalone') or remove the adapter for a static site.
• SvelteKit with adapter-auto or a provider adapter → use @sveltejs/adapter-node or @sveltejs/adapter-static.

Monorepos

• Set the root directory to the app's folder, or
• leave it at the repository root: if the root package.json delegates to a sub-folder (npm --prefix web run build, cd web && ..., pnpm --filter web build, npm -w web ...), or is a workspace with exactly one framework app, the builder finds the app. Workspaces are installed at the root.

Other languages: Nixpacks

Python, Go, Ruby, PHP, Java, Rust, Elixir and other languages fall back to Nixpacks. See the guides for Python and Go. You can also select Nixpacks explicitly in the service settings.

What gets ignored

The builder deletes macOS metadata files (._* and .DS_Store) from the checkout before building, and never sends .git or node_modules into the build context.

Next

• Build settings: root directory, build and start command overrides, watch paths
• Build variables: VITE_*, NEXT_PUBLIC_* and other build-time values
• Node.js and package managers
• Build resources: memory per plan and build timeouts
• Troubleshooting