From 026b9547b91e5500d974c4021f23f37ae7165ae2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fredrik=20Adel=C3=B6w?= <freben@gmail.com>
Date: Thu, 18 Jun 2020 20:52:25 +0200
Subject: [PATCH] address comments

---
 app-config.yaml                               |  3 +-
 .../src/service/lib/ServiceBuilderImpl.ts     | 37 ++++---------------
 .../backend-common/src/service/lib/config.ts  | 28 ++++++++++----
 3 files changed, 30 insertions(+), 38 deletions(-)

diff --git a/app-config.yaml b/app-config.yaml
index c5777be4fa..39527c20bd 100644
--- a/app-config.yaml
+++ b/app-config.yaml
@@ -4,8 +4,7 @@ app:
 
 backend:
   baseUrl: http://localhost:7000
-  bindPort: 7000
-  bindHost: localhost
+  listen: 0.0.0.0:7000
   cors:
     origin: http://localhost:3000
     methods: [GET, POST, PUT, DELETE]
diff --git a/packages/backend-common/src/service/lib/ServiceBuilderImpl.ts b/packages/backend-common/src/service/lib/ServiceBuilderImpl.ts
index 3cceec0e87..19418b2671 100644
--- a/packages/backend-common/src/service/lib/ServiceBuilderImpl.ts
+++ b/packages/backend-common/src/service/lib/ServiceBuilderImpl.ts
@@ -57,11 +57,11 @@ export class ServiceBuilderImpl implements ServiceBuilder {
     }
 
     const baseOptions = readBaseOptions(backendConfig);
-    if (baseOptions.bindPort) {
-      this.port = baseOptions.bindPort;
+    if (baseOptions.listenPort) {
+      this.port = baseOptions.listenPort;
     }
-    if (baseOptions.bindHost) {
-      this.host = baseOptions.bindHost;
+    if (baseOptions.listenHost) {
+      this.host = baseOptions.listenHost;
     }
 
     const corsOptions = readCorsOptions(backendConfig);
@@ -122,7 +122,7 @@ export class ServiceBuilderImpl implements ServiceBuilder {
 
       const server = stoppable(
         app.listen(port, host, () => {
-          logger.info(`Listening on port ${port}`);
+          logger.info(`Listening on ${host}:${port}`);
         }),
         0,
       );
@@ -143,31 +143,10 @@ export class ServiceBuilderImpl implements ServiceBuilder {
     logger: Logger;
     corsOptions?: cors.CorsOptions;
   } {
-    let port: number;
-    if (this.port !== undefined) {
-      port = this.port;
-    } else {
-      port = parseInt(process.env.PORT ?? '', 10) || DEFAULT_PORT;
-    }
-
-    let host: string;
-    if (this.host !== undefined) {
-      host = this.host;
-    } else {
-      host = process.env.HOST || DEFAULT_HOST;
-    }
-
-    let logger: Logger;
-    if (this.logger) {
-      logger = this.logger;
-    } else {
-      logger = getRootLogger();
-    }
-
     return {
-      port,
-      host,
-      logger,
+      port: this.port ?? DEFAULT_PORT,
+      host: this.host ?? DEFAULT_HOST,
+      logger: this.logger ?? getRootLogger(),
       corsOptions: this.corsOptions,
     };
   }
diff --git a/packages/backend-common/src/service/lib/config.ts b/packages/backend-common/src/service/lib/config.ts
index ead13cccec..064eacc4f2 100644
--- a/packages/backend-common/src/service/lib/config.ts
+++ b/packages/backend-common/src/service/lib/config.ts
@@ -18,8 +18,8 @@ import { ConfigReader } from '@backstage/config';
 import { CorsOptions } from 'cors';
 
 export type BaseOptions = {
-  bindPort?: number;
-  bindHost?: string;
+  listenPort?: number;
+  listenHost?: string;
 };
 
 /**
@@ -31,16 +31,17 @@ export type BaseOptions = {
  * @example
  * ```json
  * {
- *   baseUrl: "http://localhost:7000"
- *   bindPort: 7000
- *   bindHost: "0.0.0.0"
+ *   baseUrl: "http://localhost:7000",
+ *   listen: "0.0.0.0:7000"
  * }
  * ```
  */
 export function readBaseOptions(config: ConfigReader): BaseOptions {
+  // TODO(freben): Expand this to support more addresses and perhaps optional
+  const { host, port } = parseListenAddress(config.getString('listen'));
   return removeUnknown({
-    bindPort: config.getOptionalNumber('bindPort'),
-    bindHost: config.getOptionalString('bindHost'),
+    listenPort: port,
+    listenHost: host,
   });
 }
 
@@ -110,3 +111,16 @@ function removeUnknown<T extends object>(obj: T): T {
     Object.entries(obj).filter(([, v]) => v !== undefined),
   ) as T;
 }
+
+function parseListenAddress(value: string): { host?: string; port?: number } {
+  const parts = value.split(':');
+  if (parts.length === 1) {
+    return { port: parseInt(parts[0], 10) };
+  }
+  if (parts.length === 2) {
+    return { host: parts[0], port: parseInt(parts[1], 10) };
+  }
+  throw new Error(
+    `Unable to parse listen address ${value}, expected <port> or <host>:<port>`,
+  );
+}