Runtime configuration

Load typed variables without exposing secrets to the browser.

Runable reads .env files for the active Vite mode and variables from process.env. It keeps names prefixed with RUN_, or VITE_.

Declare values

RUN_PUBLIC_API_BASE=/api
RUN_PUBLIC_FEATURE_ENABLED=true
RUN_DATABASE_URL=postgres://localhost/acme
RUN_RETRY_COUNT=3

The PUBLIC_ segment determines visibility:

Variable	Generated access	Client	Server
`RUN_PUBLIC_API_BASE`	`runtime.public.apiBase`	Yes	Yes
`RUN_PUBLIC_FEATURE_ENABLED`	`runtime.public.featureEnabled`	Yes	Yes
`RUN_DATABASE_URL`	`runtime.databaseUrl`	No	Yes
`RUN_RETRY_COUNT`	`runtime.retryCount`	No	Yes

const runtime = useRuntime();

const apiBase = runtime.public.apiBase;

if (import.meta.server) {
  console.log(runtime.databaseUrl);
}

Runable removes the prefix, converts names to camelCase, and infers booleans, numbers, arrays, JSON objects, null, and undefined.

Static accesses are also replaced during compilation:

const apiBase = import.meta.env.RUN_PUBLIC_API_BASE;

Dynamic notation such as import.meta.env[key] is not transformed. Prefer useRuntime() for the public separation and generated types.

Runable writes .app/runtime.d.ts at startup. Restart the server after adding or renaming a variable to regenerate the declaration.

A public variable is never secret

Every *_PUBLIC_* value is included in the client bundle. Never use one for a password, private token, or connection string.

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