> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thebay.cloud/llms.txt
> Use this file to discover all available pages before exploring further.

# supersonic.json

> The one file Bay reads, and the one command that writes a draft of it.

You do not have to write this file. `bay init` writes a draft from the
repository, and a repo with no config at all still ships — detection runs
instead. The file exists for everything detection cannot prove.

```json theme={null}
{
  "version": 1,
  "resources": {
    "database": { "engine": "postgres" }
  },
  "services": [
    {
      "name": "app",
      "dir": ".",
      "language": "node",
      "runtime": "node22",
      "install": "npm install",
      "start": "npm start",
      "path": "/",
      "uses": ["database"],
      "secrets": []
    }
  ]
}
```

<Note>
  The filename is still `supersonic.json`, not `bay.json`. It is read by the
  control plane, not typed by a person, and renaming it would break every config
  already committed for no gain.
</Note>

## The three top-level keys

<ResponseField name="version" type="number">
  The config format. `1` today.
</ResponseField>

<ResponseField name="resources" type="object">
  What is provisioned **once per app** — a database, a bucket. Two services share
  one database. See [Resources](/configuration/resources).
</ResponseField>

<ResponseField name="services" type="array" required>
  One entry per thing that gets built and run. See
  [Services](/configuration/services).
</ResponseField>

## Validate before you ship

```bash theme={null}
bay check
```

Resolves this file exactly as a deploy would and prints what each phase runs.
Non-zero exit on any problem. It touches no cloud and takes about two seconds.

## The lock file

A ship writes `supersonic.lock.json` next to your config: what that ship
decided — the runtime it picked, the base image, the commands it resolved. It is
there so a decision made on your behalf is one you can read and change, rather
than one you have to reverse-engineer from a build log.