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serverless-dotenv-plugin

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Preload function environment variables into Serverless. Use this plugin if you have variables stored in a .env file that you want loaded into your functions.

This used to also preload environment variables into your serverless.yml config, but no longer does with serverless>=2.26.0. See this discussion thread or the FAQ below for details on the impact of how environment variables are loaded with serverless>=2.26.0 and serverless>=3.0.0.**

Do you need this plugin?

Serverless Framework can now natively resolve ${env:xxx} variables from .env files by setting useDotenv: true in the configuration:

useDotenv: true

provider:
  environment:
    FOO: ${env:FOO}

For more complex situations, you will need to wire up dotenv yourself.

This plugin is only useful if you want to automatically import all variables from .env into functions:

plugins:
  - serverless-dotenv-plugin

provider:
  environment:
    # With the plugin enabled, all variables in .env are automatically imported

Install and Setup

First, install the plugin:

> npm i -D serverless-dotenv-plugin

Next, add the plugin to your serverless config file:

service: myService
plugins:
  - serverless-dotenv-plugin
...

Now, just like you would using dotenv in any other JS application, create your .env file in the root of your app:

DYNAMODB_TABLE=myTable
AWS_REGION=us-west-1
AUTH0_CLIENT_ID=abc12345
AUTH0_CLIENT_SECRET=12345xyz

When deploying, all the variables listed in .env will automatically be available in the deployed functions.

Automatic ENV File Resolution

By default, the plugin looks for the file: .env. In most use cases this is all that is needed. However, there are times where you want different env files based on environment. For instance:

.env.development
.env.production

When you deploy with NODE_ENV set: NODE_ENV=production sls deploy the plugin will look for files named .env, .env.production, .env.production.local. If for some reason you can't set NODE_ENV, you could always just pass it in as an option: sls deploy --env production or sls deploy --stage production. If NODE_ENV, --env or --stage is not set, it will default to development.

DEPRECATION WARNING: as of serverless>=3.0.0, --env will not be supported due to changes to the Serverless Framework. See FAQ for details.

The precedence between the options is the following: NODE_ENV > --env > --stage

The env resolution pattern follows the one used by Rail's dotenv and create-react-app

Valid .env file namesDescription
.envDefault file, always included
.env.localIncluded in all environments except test
.env.developmentIf NODE_ENV or --env or --stage is not set, will try to load .env.development.
.env.{ENV}If NODE_ENV or --env or --stage is set, will try to load .env.{env}.
.env.{ENV}.localEvery env set up in .env.{ENV}.local will override other envs

Note: .env, .env.development, and .env.production files should be included in your repository as they define defaults. .env*.local should be added to .gitignore, as those files are intended to be ignored. .env.local is where secrets can be stored.

Lambda Environment Variables

Again, remember that when you deploy your service, the plugin will inject these environment vars into every lambda functions you have and will therefore allow you to reference them as process.env.AUTH0_CLIENT_ID (Nodejs example). If this behaviour is not desireable, set include to [].

Plugin options

All options are optional.

custom:
  dotenv:
    # default: project root
    path: path/to/my/dotenvfiles

    # if set, ignores `path` option, and only uses the dotenv file at this location
    # basePath: path/to/my/.env

    # if set, uses provided dotenv parser function instead of built-in function
    dotenvParser: dotenv.config.js

    # default: adds all env variables found in your dotenv file(s)
    # this option must be set to `[]` if `provider.environment` is not a literal string
    include:
      - DDB_TABLE
      - S3_BUCKET

    # default: does not exclude any env variables found in your dotenv file(s)
    # does nothing if `include` is set
    exclude:
      - AWS_ACCESS_KEY_ID
      - AWS_SECRET_ACCESS_KEY
      - AWS_SESSION_TOKEN
      - NODE_ENV              # Can not be declared for Google Cloud Functions

    # defaults to `true`
    logging: false

    # default: plugin does not cause an error if any file or env variable is missing
    required:
      # default: []
      env:
        - API_KEY

      # default: false
      file: true

    # default: true
    variableExpansion: false

Example dotenvParser file:

// You can bring your own or use the one provided by the plugin
const dotenv = require('dotenv')
const dotenvExpand = require('dotenv-expand')

module.exports = function({ dotenv, paths }) {
  const envVarsArray = [...paths]
    .reverse()
    .map(path => {
      const parsed = dotenv.config({ path })
      return dotenvExpand(parsed).parsed
    })

  return envVarsArray.reduce((acc, curr) => ({ ...acc, ...curr }), {})
}

Examples

You can find example usage in the examples folder.

Changelog

The changelog is available in the CHANGELOG.md file in the package or on GitHub.

FAQ

This plugin loads the dotenv environment variables inside the plugin constructor. Aside from legacy reasons, this also means all your dotenv environment variables are available to the other plugins being loaded.

However, Serverless variables are not resolved in the constructor:

Variable references in the serverless instance are not resolved before a Plugin's constructor is called, so if you need these, make sure to wait to access those from your hooks. ~https://www.serverless.com/framework/docs/providers/aws/guide/plugins/#plugins/

This is important for several FAQ items below.

How has changes to the Serverless Framework affected when environment variables are loaded?

serverless>=2.26.0

serverless/serverless#8987 changed the order of when plugins are initialized in relationship to variable resolution as part of a larger initiative outlined in serverless/serverless#8364. Because of this, any env var references inside JavaScript files will now get evaluated too early in the process.

serverless>=3.0.0

env variables will get resolved before this plugin is initialized. This means env variables inside serverless.yml can no longer rely on this plugin to load them from dotenv files. See serverless/serverless#8364 for more details on the changes made to the Serverless Framework variables engine.

The Serverless Framework has basic dotenv support built-in. For support with more complicated workflows with dotenv, see serverless-dotenv-example for details.

You can continue to use this plugin to automatically load environment variables into all your functions using dotenv.

How has changes to the Serverless Framework affected configuration options?

See deprecation code UNSUPPORTED_CLI_OPTIONS for more details. This was introduced in serverless/serverless#9171.

serverless>=2.32.0

Using the --env CLI option will now result in the following warning:

Detected unrecognized CLI options: "--env".
Starting with the next major, Serverless Framework will report them with a thrown error
More Info: https://www.serverless.com/framework/docs/deprecations/#UNSUPPORTED_CLI_OPTIONS

serverless>=3.0.0

Using the --env CLI option will now result in the following error:

Error:
Detected unrecognized CLI options: "--env".

Why do env vars already defined by the system take higher precedence?

The Serverless Framework has basic dotenv support built-in. If you are loading variables from .env at the project root, it is possible the Serverless Framework preloads that env var before this plugin does.

As well, because of the variables engine changed in serverless>=2.26.0 (see above), env variables can also be resolved before this plugin runs, which means Serverless could take the values already defined in the system before the plugin loads env vars via dotenv.

Why doesn't the basePath or path options support Serverless variables?

Because Serverless variables have not been interpolated when this plugin runs, basePath and path will always be treated like literal strings (e.g. ${opt:stage} would be presented to the plugin, not the passed in via --stage). The suggested pattern is to store all your dotenv files in one folder, and rely on NODE_ENV, --env, or --stage to resolve to the right file.

There are no plans to support anything other than literal strings at this time, although you are free to discuss this in #52.

Why doesn't this plugin work when provider.environment references another file?

Upgrade to serverless>=2.26.0. The new variables engine introduced in the Serverless Framework in v2.26.0 now resolves file variables first before loading initializing any plugins.

Before v2.26.0, Serverless variables do not get interpolated before this plugin gets initialized, causing provider.environment to be presented to this plugin uninterpolated (e.g. ${file(./serverless-env.yml):environment}). Because of this, the plugin tries to append items to a string instead of a list.

To work around this, you can set the include option to [] to avoid adding any environment variables to provider.environment. However, this means you will have to wire up the environment variables yourself by referencing every single one you need. E.g.

provider:
  environment:
    - DDB_TABLE: ${env:DDB_TABLE}

More details are available at #38.

Contributing

Because of the highly dependent nature of this plugin (i.e. thousands of developers depend on this to deploy their apps to production) I cannot introduce changes that are backwards incompatible. Any feature requests must first consider this as a blocker. If submitting a PR ensure that the change is developer opt-in only meaning it must guarantee that it will not affect existing workflows, it's only available with an opt-in setting. I appreciate your patience on this. Thanks.