Detection

With the runtime auto, Ferry finds the runtime from the files in the root directory.

Dockerfile. The runtime is docker.

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Ferry looks for these files in this order. The first file that it finds wins.

The files

These files tell Ferry the runtime.

File in the root directory	Runtime
`Dockerfile`	`docker`
`package.json`, `bun.lockb` or `bun.lock`	`node`
`requirements.txt`, `pyproject.toml` or `Pipfile`	`python`
`go.mod`	`go`
`Cargo.toml`	`rust`
`Gemfile`	`ruby`
`index.html`	`static`

Ferry looks in the root directory only, not in the folders below it.

Deploy log

==> Detected Node.js runtime

Case	Result
The Dockerfile path is not `Dockerfile` (`--dockerfile`)	The runtime is `docker`.
The service is a static site	nginx serves the files as they are.
All other cases	The build fails with `could not detect the runtime`.

To correct the failure, add one of the files, or set the runtime.