generate-env

Reads a .env.<Environment> file and writes .env, optionally merging in CloudFormation outputs from other deployed packages.

Usage

carlin generate-env

By default this reads .env.Staging and writes .env. The environment is resolved from the --environment flag, falling back to --default-environment (default: Staging).

Options

Option	Alias	Default	Description
--default-environment	-d	Staging	Fallback environment name when --environment is not set
--path	-p	./	Directory where .env.<Environment> source files are looked up

Merging Outputs from Other Packages

In a monorepo it is common for one package to need outputs from a stack deployed by another package (e.g. a frontend app needing the AppSync URL from a backend API package). Use envFromDeployOutputs in carlin.yml to map those outputs into your .env file.

# carlin.yml
envFromDeployOutputs:
  - dir: ../graph-api # relative path to the other package
    variables:
      VITE_APPSYNC_GRAPHQL_ENDPOINT: AppSyncApiGraphQLUrl.OutputValue
      VITE_APPSYNC_CONSOLE_URL: AppSyncApiGraphQLUrl.ExportName

Each entry under envFromDeployOutputs reads .carlin/latest-deploy.json inside dir (written by carlin deploy). The variable value is a dot-notation path into the outputs object:

• AppSyncApiGraphQLUrl — shorthand for AppSyncApiGraphQLUrl.OutputValue
• AppSyncApiGraphQLUrl.OutputValue — explicit field selection
• AppSyncApiGraphQLUrl.ExportName — any other field on the output object

If the file cannot be read, or the specified output key/field does not exist, a warning is logged and that variable is skipped.

Deploy output variables are merged into the generated .env. If a key from envFromDeployOutputs already exists in .env.<Environment>, the deploy output value wins — the static value is removed. This lets you commit a sensible default in .env.Staging and have the real deployed value override it automatically.

# .env.Staging (source)
EXISTING_VAR=from-env-staging-file
VITE_APPSYNC_GRAPHQL_ENDPOINT=https://static-placeholder.example.com/graphql

# .env (generated)
EXISTING_VAR=from-env-staging-file

VITE_APPSYNC_GRAPHQL_ENDPOINT=https://wlzbneunwjctrddgrvlllm.appsync-api.us-east-1.amazonaws.com/graphql
VITE_APPSYNC_CONSOLE_URL=MyStack:AppSyncApiGraphQLUrl

Disabling Deploy Outputs for a Specific Environment

You can set envFromDeployOutputs: null under a specific environment in carlin.yml to skip deploy output resolution entirely for that environment. This is useful when a particular environment (e.g. Production) should always use values baked into the static .env.Production file rather than pulling live stack outputs.

# carlin.yml
envFromDeployOutputs:
  - dir: ../graph-api
    variables:
      VITE_APPSYNC_GRAPHQL_ENDPOINT: AppSyncApiGraphQLUrl.OutputValue

environments:
  Staging:
    cloudfront: true
  Production:
    cloudfront: true
    envFromDeployOutputs: null # disables deploy output resolution for Production

When carlin generate-env --environment Production runs, it reads .env.Production as normal but does not attempt to read any latest-deploy.json files. The generated .env contains only the static values from .env.Production.