Env Validation

Miso automatically loads .env files into your scripts — you don’t need --env for that. The --env flag and miso env are for validation: checking that variables exist and match their expected types before running.

Usage

miso env validates environment variables from your .env files against rules defined in miso.json.


miso env

Or use --env as a flag behind other commands to validate before running:


miso dev --env
miso build --env

Quick Start

Add an env array to miso.json, with one entry per app or .env file:

>miso.json

{
	"env": [
		{
			"label": "web",
			"path": "apps/web/.env.local",
			"variables": {
				"PORT": "port",
				"DATABASE_URL": "url"
			}
		},
		{
			"label": "api",
			"path": "apps/api/.env",
			"variables": {
				"REDIS_URL": {
					"type": "url",
					"schemes": ["redis", "rediss"]
				}
			}
		}
	]
}

Run miso env before starting your app (or in CI):


miso env && miso dev

Each entry is validated independently. If a variable fails in the api entry, the error will say so:


api: missing required variable: REDIS_URL

Auto-Discovery

Even without an env block in miso.json, Miso automatically loads a .env file into every script it runs. It walks the following candidates in order and loads the first one it finds:

Priority	File
1	`.env.local`
2	`.env.production`
3	`.env.development`
4	`.env`

Variables already set in the shell environment take precedence over values in the file — Miso never overrides a variable that is already present in the process environment.

In a monorepo, auto-discovery searches the workspace root rather than the project root when you run a workspace-scoped script.

Next Steps

Configure labels, paths, required variables, and validation rules
See the Types & VarConfig reference for all supported types and options