Add Environment Variable Override (#4085)

* Add Environment Variable Override

I need to be able to manage settings on this service via Environment Variables.   I've added the ability to override anything in the settings schema with a corresponding environment variable.  

e.g. to override settings.serial.port you can set ZIGBEE2MQTT_SERIAL_PORT=/dev/ttyS0
to override the mqtt username you can set ZIGBEE2MQTT_MQTT_USER=testusername

This new addition will not perform any action on existing installations unless the matching environment variable is set.  I have tested this setting string, number, boolean, object and array values.

* Adding test case for environment variables and slight modification to ensure 100% code coverage.

* Adding a test to confirm that env variables will set non default values.  Also realized that I was errantly applying the env variables to the defaults for testing.  Understanding what this is doing more clearly I realize that should be clean.

* Refactoring to

1. Remove the test variables from the schema and defaults and manually reflect the tests in the test.

2. Rename environment variable base from ZIGBEE2MQTT_ to ZIGBEE2MQTT_CONFIG_

* Small improvements

* Removing the unneeded test.

Co-authored-by: Koen Kanters <koenkanters94@gmail.com>

lib/util/settings.js

@@ -438,9 +438,52 @@ function read() {
     return s;
 }
 
+function applyEnvironmentVariables(settings) {
+    const iterate = (obj, path) => {
+        Object.keys(obj).forEach((key) => {
+            if (key !== 'type') {
+                if (key !== 'properties') {
+                    const type = (obj[key].type || 'object').toString();
+                    const envPart = path.reduce((acc, val) => `${acc}${val}_`, '');
+                    const envVariableName = (`ZIGBEE2MQTT_CONFIG_${envPart}${key}`).toUpperCase();
+                    if (process.env[envVariableName]) {
+                        const setting = path.reduce((acc, val, index) => {
+                            acc[val] = acc[val] || {};
+                            return acc[val];
+                        }, settings);
+
+                        if (type.indexOf('object') >= 0 || type.indexOf('array') >= 0) {
+                            setting[key] = JSON.parse(process.env[envVariableName]);
+                        }
+                        if (type.indexOf('number') >= 0) {
+                            setting[key] = process.env[envVariableName] * 1;
+                        }
+                        if (type.indexOf('boolean') >= 0) {
+                            setting[key] = process.env[envVariableName].toLowerCase() === 'true';
+                        }
+                        if (type.indexOf('string') >= 0) {
+                            setting[key] = process.env[envVariableName];
+                        }
+                    }
+                }
+
+                if (typeof obj[key] === 'object') {
+                    const newPath = [...path];
+                    if (key !== 'properties') {
+                        newPath.push(key);
+                    }
+                    iterate(obj[key], newPath);
+                }
+            }
+        });
+    };
+    iterate(schema.properties, []);
+}
+
 function get() {
     if (!_settings) {
         _settings = read();
+        applyEnvironmentVariables(_settings);
     }
 
     return _settings;
@@ -743,11 +786,14 @@ module.exports = {
     // For tests only
     _write: write,
     _reRead: () => {
-        _settings = read();
-        _settingsWithDefaults = objectAssignDeep.noMutate(defaults, get());
+        _settings = null;
+        get();
+        _settingsWithDefaults = null;
+        getWithDefaults();
     },
     _clear: () => {
         _settings = null;
+        _settingsWithDefaults = null;
     },
     _getDefaults: () => defaults,
 };

test/settings.test.js

@@ -9,6 +9,7 @@ const devicesFile = data.joinPath('devices.yaml');
 const groupsFile = data.joinPath('groups.yaml');
 const secretFile = data.joinPath('secret.yaml');
 const yaml = require('js-yaml');
+const objectAssignDeep = require(`object-assign-deep`);
 
 const minimalConfig = {
     permit_join: true,
@@ -27,11 +28,19 @@ describe('Settings', () => {
     const remove = (file) => {
         if (fs.existsSync(file)) fs.unlinkSync(file);
     }
+    const clearEnvironmentVariables = () => {
+        Object.keys(process.env).forEach((key) => { 
+            if(key.indexOf('ZIGBEE2MQTT_CONFIG_') >= 0) {
+                delete process.env[key];
+            }
+        });
+    }
 
     beforeEach(() => {
         remove(configurationFile);
         remove(devicesFile);
         remove(groupsFile);
+        clearEnvironmentVariables();
     });
 
     it('Should return default settings', () => {
@@ -53,6 +62,29 @@ describe('Settings', () => {
         expect(s).toStrictEqual(expected);
     });
 
+    it('Should apply environment variables', () => {
+        process.env['ZIGBEE2MQTT_CONFIG_SERIAL_DISABLE_LED'] = 'true';
+        process.env['ZIGBEE2MQTT_CONFIG_ADVANCED_SOFT_RESET_TIMEOUT'] = 1;
+        process.env['ZIGBEE2MQTT_CONFIG_EXPERIMENTAL_OUTPUT'] = 'csvtest';
+        process.env['ZIGBEE2MQTT_CONFIG_ADVANCED_AVAILABILITY_BLOCKLIST'] = '["0x43597f0dac781b1e", "x223b0aef2ae8d1b0"]';
+        process.env['ZIGBEE2MQTT_CONFIG_MAP_OPTIONS_GRAPHVIZ_COLORS_FILL'] = '{"enddevice": "#ff0000", "coordinator": "#00ff00", "router": "#0000ff"}';
+        process.env['ZIGBEE2MQTT_CONFIG_MQTT_BASE_TOPIC'] = 'testtopic';
+
+        write(configurationFile, {});
+        const s = settings.get();
+        const expected = objectAssignDeep.noMutate({}, settings._getDefaults());
+        expected.devices = {};
+        expected.groups = {};
+        expected.serial.disable_led = true;
+        expected.advanced.soft_reset_timeout = 1;
+        expected.experimental.output = 'csvtest';
+        expected.advanced.availability_blocklist = ['0x43597f0dac781b1e', 'x223b0aef2ae8d1b0'];
+        expected.map_options.graphviz.colors.fill = {enddevice: '#ff0000', coordinator: '#00ff00', router: '#0000ff'};
+        expected.mqtt.base_topic = 'testtopic';
+
+        expect(s).toStrictEqual(expected);
+    });
+
     it('Should add devices', () => {
         write(configurationFile, {});
         settings.addDevice('0x12345678');