Getting Started

Requirements

You will need Node.js >= 12 and a PostgreSQL >= 10 database instance to be able to run Unleash.

When starting Unleash you must specify a database URI (can be set as environment variable DATABASE_URL) which includes a username and password, that have rights to migrate the database.

On startup Unleash will perform necessary migrations if needed.

Start Unleash

1. The simplest way to get started:

$ npm install unleash-server -g
$ unleash -d postgres://unleash_user:password@localhost:5432/unleash -p 4242

Unleash started on http://localhost:4242

2. Or programmatically:

You can also depend on unleash

const unleash = require('unleash-server');

unleash
  .start({
    databaseUrl: 'postgres://unleash_user:password@localhost:5432/unleash',
    port: 4242,
  })
  .then(unleash => {
    console.log(
      `Unleash started on http://localhost:${unleash.app.get('port')}`,
    );
  });

Available unleash options include:

  • db - The database configuration object taking the following properties:
    • user - the database username (DATABASE_USERNAME)
    • password - the database password (DATABASE_PASSWORD)
    • host - the database hostname (DATABASE_HOST)
    • port - the datbase port defaults to 5432 (DATABASE_PORT)
    • database - the database name to be used (DATABASE_NAME)
    • ssl - an object describing ssl options, see https://node-postgres.com/features/ssl (DATABASE_SSL, as a stringified json object)
  • databaseUrl - the postgres database url to connect to. Only used if db object is not specified. Should include username/password. This value may also be set via the DATABASE_URL environment variable. Alternatively, if you would like to read the database url from a file, you may set the DATABASE_URL_FILE environment variable with the full file path. The contents of the file must be the database url exactly.
  • databaseSchema - the postgres database schema to use. Defaults to 'public'.
  • port - which port the unleash-server should bind to. If port is omitted or is 0, the operating system will assign an arbitrary unused port. Will be ignored if pipe is specified. This value may also be set via the HTTP_PORT environment variable
  • host - which host the unleash-server should bind to. If host is omitted, the server will accept connections on the unspecified IPv6 address (::) when IPv6 is available, or the unspecified IPv4 address (0.0.0.0) otherwise. This value may also be set via the HTTP_HOST environment variable
  • pipe - parameter to identify IPC endpoints. See https://nodejs.org/api/net.html#net_identifying_paths_for_ipc_connections for more details
  • enableLegacyRoutes (boolean) - allows you to turn on/off support for legacy routes to support older clients. Disabled by default. Will be removed in 4.x.
  • serverMetrics (boolean) - use this option to turn on/off prometheus metrics.
  • preHook (function) - this is a hook if you need to provide any middlewares to express before unleash adds any. Express app instance is injected as first argument.
  • preRouterHook (function) - use this to register custom express middlewares before the unleash specific routers are added. This is typically how you would register custom middlewares to handle authentication.
  • adminAuthentication (string) - use this when implementing custom admin authentication securing-unleash. Possible values are:
    • none - will disable authentication altogether
    • unsecure - (default) will use simple cookie based authentication. UI will require the user to specify an email in order to use unleash.
    • custom - use this when you implement your own custom authentication logic.
  • ui (object) - Set of UI specific overrides. You may set the following keys: headerBackground, environment, slogan.
  • getLogger (function) - Used to register a [custom log provider](#How do I configure the log output).
  • eventHook (function(event, data)) - If provided, this function will be invoked whenever a feature is mutated. The possible values for event are 'feature-created', 'feature-updated', 'feature-archived', 'feature-revived'. The data argument contains information about the mutation. Its fields are type (string) - the event type (same as event); createdBy (string) - the user who performed the mutation; data - the contents of the change. The contents in data differs based on the event type; For 'feature-archived' and 'feature-revived', the only field will be name - the name of the feature. For 'feature-created' and 'feature-updated' the data follows a schema defined in the code here. See an example here.
  • baseUriPath (string) - use to register a base path for all routes on the application. For example /my/unleash/base (note the starting /). Defaults to /. Can also be configured through the environment variable BASE_URI_PATH.
  • secureHeaders (boolean) - use this to enable security headers (HSTS, CSP, etc) when serving Unleash from HTTPS. Can also be configured through the environment variable SECURE_HEADERS.

Disabling Auto-Start

If you're using unleash as part of a larger express app, you can disable the automatic server start by calling server.create. It takes the same options as sevrer.start, but will not begin listening for connections.

const unleash = require('unleash-server');
// ... const app = express();

unleash
  .create({
    databaseUrl: 'postgres://unleash_user:password@localhost:5432/unleash',
    port: 4242,
  })
  .then(result => {
    app.use(result.app);
    console.log(`Unleash app generated and attached to parent application`);
  });

3. Docker

You can also use the hosted docker image to start the Unleash server

docker run -d -e DATABASE_URL=postgres://user:pass@10.200.221.11:5432/unleash unleashorg/unleash-server

Securing Unleash

Unleash also have extension points where you can integrate Unleash with your authentication provider (OAuth 2.0). Read more about securing unleash.

How do I configure the log output?

By default, unleash uses log4js to log important information. It is possible to swap out the logger provider (only when using Unleash programmatically). You do this by providing an implementation of the getLogger function as This enables filtering of log levels and easy redirection of output streams.

function getLogger(name) {
  // do something with the name
  return {
    debug: console.log,
    info: console.log,
    warn: console.log,
    error: console.error,
  };
}

The logger interface with its debug, info, warn and error methods expects format string support as seen in debug or the JavaScript console object. Many commonly used logging implementations cover this API, e.g., bunyan, pino or winston.

Client SDK →