allow to set the server hostname via environment variable HOST

Author: striezel

changelog.md

@@ -11,13 +11,18 @@ application, major version changes in Plotly.js will also trigger a major
 version change in this application.
 
 
-## Version 1.5.0-pre1 (2021-08-01)
+## Version 1.5.0 (2021-08-01)
 
 * __[new feature]__
 The port to which the server binds can now be changed by setting the environment
 variable `PORT`. If `PORT` is not set or is not a valid port number, then the
 default port 3000 is used.
 
+* __[new feature]__
+The hostname which the server shall use can now be changed by setting the
+environment variable `HOST`. If `HOST` is not set, then `localhost` will be
+used as default.
+
 ## Version 1.4.2 (2021-08-01)
 
 * __[maintenance]__

export-server/package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "plotly-node-export-server",
-  "version": "1.5.0-pre1",
+  "version": "1.5.0",
   "description": "Plotly.js Node.js export server",
   "repository": {
     "url": "https://gitlab.com/striezel/plotly-node-export-server.git",

export-server/package.json

@@ -26,7 +26,8 @@ const phantomize = require('./phantomize.js');
 const url = require('url');
 const uuidv4 = require('uuid/v4');
 
-const hostname = 'localhost';
+// Use hostname from environment variable HOST, if it is set.
+const hostname = process.env.HOST || 'localhost';
 // Use port from environment variable PORT, if it is set and valid.
 const parsedPort = parseInt(process.env.PORT);
 if (process.env.PORT) {

export-server/server.js

@@ -69,6 +69,16 @@ npm start
 In these cases the server will bind to port 4000 instead of the default port
 3000.
 
+The hostname can be changed, too, by setting the `HOST` environment variable in
+the same manner, e. g.:
+
+``` bash
+export HOST=0.0.0.0
+npm start
+```
+
+If `HOST` is not set, then `localhost` will be used as hostname.
+
 ## Usage
 
 To generate a PNG file of a Plotly plot, just send an HTTP POST request to the