Fix: Add support for IPC connections.

Read this for more details:
https://nodejs.org/api/net.html#net_identifying_paths_for_ipc_connections

docs/getting-started.md

@@ -45,7 +45,9 @@ Available unleash options include:
 
 - **databaseUrl** - the postgres database url to connect to. Should include username/password.
 - **databaseSchema** - the postgres database schema to use. Defaults to 'public'.
-- **port** - which port the unleash-server should bind to.
+- **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.
+- **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.
+- **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. Enabled by default.
 - **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.

lib/options.js

@@ -10,6 +10,7 @@ const DEFAULT_OPTIONS = {
     databaseSchema: 'public',
     port: process.env.HTTP_PORT || process.env.PORT || 4242,
     host: process.env.HTTP_HOST,
+    pipe: undefined,
     baseUriPath: process.env.BASE_URI_PATH || '',
     serverMetrics: true,
     enableLegacyRoutes: true,
@@ -40,6 +41,10 @@ module.exports = {
             );
         }
 
+        options.listen = options.pipe
+            ? { path: options.pipe }
+            : { port: options.port, host: options.host };
+
         return options;
     },
 };

lib/server-impl.js

@@ -46,8 +46,8 @@ async function createApp(options) {
         });
     }
 
-    const server = app.listen({ port: options.port, host: options.host }, () =>
-        logger.info(`Unleash started on port ${server.address().port}`)
+    const server = app.listen(options.listen, () =>
+        logger.info('Unleash has started.', server.address())
     );
 
     return new Promise((resolve, reject) => {