Possibility to switch between different environments

.eslintrc

@@ -1,4 +1,7 @@
 {
+    "parserOptions": {
+        "ecmaVersion": 2018
+    },
     "env": {
         "browser": false,
         "es6": true,
@@ -19,12 +22,21 @@
         "no-eval": 2,
         "no-unused-vars": 2,
         "no-lonely-if": 2,
-        "quotes": [2, "single"],
-        "strict": [2, "global"],
-        "prettier/prettier": [2, {
-            "singleQuote": true,
-            "tabWidth": 4
-        }]
+        "quotes": [
+            2,
+            "single"
+        ],
+        "strict": [
+            2,
+            "global"
+        ],
+        "prettier/prettier": [
+            2,
+            {
+                "singleQuote": true,
+                "tabWidth": 4
+            }
+        ]
     },
     "globals": {
         "require": false,

lib/parse-environment.js

@@ -0,0 +1,9 @@
+'use strict';
+
+module.exports = url => {
+    const percentRegEx = /\{([^}]+)\}/;
+    const matches = percentRegEx.exec(url);
+    return matches != null && Object.keys(process.env).includes(matches[1])
+        ? url.replace(matches[0], process.env[matches[1]])
+        : url;
+};

lib/request-fragment.js

@@ -5,6 +5,7 @@ const https = require('https');
 const url = require('url');
 const { globalTracer, FORMAT_HTTP_HEADERS } = require('opentracing');
 const tracer = globalTracer();
+const parseEnvironmentVariables = require('./parse-environment');
 
 // By default tailor supports gzipped response from fragments
 const requiredHeaders = {
@@ -30,7 +31,7 @@ module.exports = filterHeaders => (
     span = null
 ) =>
     new Promise((resolve, reject) => {
-        const parsedUrl = url.parse(fragmentUrl);
+        const parsedUrl = url.parse(parseEnvironmentVariables(fragmentUrl));
         const options = Object.assign(
             {
                 headers: Object.assign(

tests/parse-environment.js

@@ -0,0 +1,54 @@
+'use strict';
+const assert = require('assert');
+const parseEnvironmentVariables = require('../lib/parse-environment');
+
+describe('Parse Environment', () => {
+    it('should return the same url when no brackets found', () => {
+        const fragmentUrl = 'https://test.zalando.de/#/blub/12';
+        assert.strictEqual(
+            parseEnvironmentVariables(fragmentUrl),
+            fragmentUrl,
+            'The url is not the same anymore'
+        );
+    });
+
+    it('should return the same url when only one bracket is found', () => {
+        let fragmentUrl = 'https://{test.zalando.de/#/blub/12';
+        assert.strictEqual(
+            parseEnvironmentVariables(fragmentUrl),
+            fragmentUrl,
+            'The url is not the same anymore'
+        );
+
+        fragmentUrl = 'https://test.zalando.de}/#/blub/12';
+        assert.strictEqual(
+            parseEnvironmentVariables(fragmentUrl),
+            fragmentUrl,
+            'The url is not the same anymore'
+        );
+    });
+
+    it('should return the same url when no environment variable is found', () => {
+        const envVarName = `TEST__ROOT_HOST_${+new Date()}`;
+        const fragmentUrl = `https://{${envVarName}}/#/blub/12`;
+        delete process.env[envVarName];
+        assert.strictEqual(
+            parseEnvironmentVariables(fragmentUrl),
+            fragmentUrl,
+            'The url is not the same anymore'
+        );
+    });
+
+    it('should return the modified url when everything is given', () => {
+        const envVarName = `TEST__ROOT_HOST_${+new Date()}`;
+        const envVarValue = 'test.zalando.de';
+        const fragmentUrl = `https://{${envVarName}}/#/blub/12`;
+        process.env[envVarName] = envVarValue;
+        assert.strictEqual(
+            parseEnvironmentVariables(fragmentUrl),
+            fragmentUrl.replace(`{${envVarName}}`, envVarValue),
+            'The url is the same'
+        );
+        delete process.env[envVarName];
+    });
+});