feat(config): add support for environment variable placeholders in config

apps/generator-cli/src/README.md

@@ -30,7 +30,7 @@ To make that happen, a version management was added to the package.
 The first time you run the command `openapi-generator-cli` the last stable version 
 of [OpenAPITools/openapi-generator](https://github.com/OpenAPITools/openapi-generator) is downloaded by default. 
 
-That version is saved in the file *openapitools.json*. Therefore you should include this file in your version control, 
+That version is saved in the file *openapitools.json*. Therefore, you should include this file in your version control, 
 to ensure that the correct version is being used next time you call the command.
 
 If you would like to use a different version of the [OpenAPITools/openapi-generator](https://github.com/OpenAPITools/openapi-generator), 
@@ -66,7 +66,7 @@ After the installation has finished you can run `npx openapi-generator-cli` or a
   "name": "my-cool-package",
   "version": "0.0.0",
   "scripts": {
-    "my-awesome-script-name": "openapi-generator-cli generate -i docs/openapi.yaml -g typescript-angular -o generated-sources/openapi --additional-properties=ngVersion=6.1.7,npmName=restClient,supportsES6=true,npmVersion=6.9.0,withInterfaces=true",
+    "my-awesome-script-name": "openapi-generator-cli generate -i docs/openapi.yaml -g typescript-angular -o generated-sources/openapi --additional-properties=ngVersion=6.1.7,npmName=restClient,supportsES6=true,npmVersion=6.9.0,withInterfaces=true"
   }
 }
 ```
@@ -164,17 +164,18 @@ is automatically used to generate your code. 🎉
 
 ##### Available placeholders
 
-| placeholder  | description                                                   | example                                               |
-|--------------|---------------------------------------------------------------|-------------------------------------------------------|
-| name         | just file name                                                | auth                                                  |
-| Name         | just file name, but starting with a capital letter            | Auth                                                  |
-| cwd          | the current cwd                                               | /Users/some-user/projects/some-project                |
-| base         | file name and extension                                       | auth.yaml                                             |
-| path         | full path and filename                                        | /Users/some-user/projects/some-project/docs/auth.yaml |
-| dir          | path without the filename                                     | /Users/some-user/projects/some-project/docs           |
-| relDir       | directory name of file relative to the glob provided          | docs                                                  |
-| relPath      | file name and extension of file relative to the glob provided | docs/auth.yaml                                        |
-| ext          | just file extension                                           | yaml                                                  |
+| placeholder | description                                                   | example                                               |
+|-------------|---------------------------------------------------------------|-------------------------------------------------------|
+| name        | just file name                                                | auth                                                  |
+| Name        | just file name, but starting with a capital letter            | Auth                                                  |
+| cwd         | the current cwd                                               | /Users/some-user/projects/some-project                |
+| base        | file name and extension                                       | auth.yaml                                             |
+| path        | full path and filename                                        | /Users/some-user/projects/some-project/docs/auth.yaml |
+| dir         | path without the filename                                     | /Users/some-user/projects/some-project/docs           |
+| relDir      | directory name of file relative to the glob provided          | docs                                                  |
+| relPath     | file name and extension of file relative to the glob provided | docs/auth.yaml                                        |
+| ext         | just file extension                                           | yaml                                                  |
+| env.<name>  | environment variable (use ${env.name} syntax)                 |                                                       |
 
 ### Using custom / private maven registry 
 
@@ -196,6 +197,17 @@ If you're using a private maven registry you can configure the `downloadUrl` and
 
 If the `version` property param is set it is not necessary to configure the `queryUrl`.
 
+`queryUrl` and `downloadUrl` can use the following placeholders:
+
+| placeholder | description                                        |
+|-------------|----------------------------------------------------|
+| groupId     | maven groupId where '.' has been replace with /    |
+| artifactId  | maven artifactId where '.' has been replace with / |
+| versionName | maven version (only for downloadUrl)               |
+| group.id    | maven groupId                                      |
+| artifact.id | maven artifactId                                   |
+| env.<name>  | environment variable name                          |
+
 ### Use locally built JAR
 In order to use a locally built jar of the generator CLI, you can copy the jar from your local build (i.e. if you were to `build` the [OpenAPITools/openapi-generator](https://github.com/OpenAPITools/openapi-generator) repository it would be in `~/openapi-generator/modules/openapi-generator-cli/target/openapi-generator-cli.jar`) into `./node_modules/@openapitools/openapi-generator-cli/versions/` and change the `version` in the `openapitools.json` file to the base name of the jar file.
 E.g.:
@@ -210,7 +222,7 @@ and then:
   "$schema": "./node_modules/@openapitools/openapi-generator-cli/config.schema.json",
   "spaces": 2,
   "generator-cli": {
-    "version": "my-local-snapshot",
+    "version": "my-local-snapshot"
   }
 }
 ```
@@ -232,7 +244,7 @@ Change your `openapitools.json` to:
 ```
 
 Example is with a snapshot of `7.17.0`, please change the `version` and `downloadUrl` accordingly.
-You can find the published snapshots in the build log of the [Publish to Maven Central Github workflow](https://github.com/OpenAPITools/openapi-generator/actions/workflows/maven-release.yml) in OpenAPI Generator repo, e.g.
+You can find the published snapshots in the build log of the [Publish to Maven Central GitHub workflow](https://github.com/OpenAPITools/openapi-generator/actions/workflows/maven-release.yml) in OpenAPI Generator repo, e.g.
 
 ```
 [INFO] Uploading to central: https://central.sonatype.com/repository/maven-snapshots/org/openapitools/openapi-generator-cli/7.17.0-SNAPSHOT/openapi-generator-cli-7.17.0-20251003.020930-8.jar

apps/generator-cli/src/app/services/config.service.spec.ts

@@ -12,6 +12,7 @@ describe('ConfigService', () => {
   let program: Command;
 
   const log = jest.fn();
+  const error = jest.fn();
 
   beforeEach(async () => {
     program = createCommand();
@@ -20,7 +21,7 @@ describe('ConfigService', () => {
     const moduleRef = await Test.createTestingModule({
       providers: [
         ConfigService,
-        { provide: LOGGER, useValue: { log } },
+        { provide: LOGGER, useValue: { log, error } },
         { provide: COMMANDER_PROGRAM, useValue: program },
       ],
     }).compile();
@@ -92,6 +93,43 @@ describe('ConfigService', () => {
       });
     });
 
+    describe('the config has values having placeholders', () => {
+      let originalEnv: NodeJS.ProcessEnv;
+
+      beforeEach(() => {
+        originalEnv = { ...process.env };
+
+        fs.readJSONSync.mockReturnValue({
+          $schema: 'foo.json',
+          spaces: 4,
+          'generator-cli': {
+            version: '1.2.3',
+            repository: {
+              queryUrl: 'https://${env.__unit_test_username}:${env.__unit_test_password}@server/api',
+              downloadUrl: 'https://${env.__unit_test_non_matching}@server/api'
+            }
+          },
+        });
+        process.env['__unit_test_username'] = 'myusername';
+        process.env['__unit_test_password'] = 'mypassword';
+      });
+
+      afterEach(() => {
+        process.env = { ...originalEnv };
+      });
+
+      it('verify placeholder replaced with env vars', () => {
+        const value = fixture.get('generator-cli.repository.queryUrl');
+        expect(value).toEqual('https://myusername:mypassword@server/api');
+      });
+
+      it('verify placeholders not matching env vars are not replaced', () => {
+        const value = fixture.get('generator-cli.repository.downloadUrl');
+        expect(value).toEqual('https://${env.__unit_test_non_matching}@server/api');
+        expect(error).toHaveBeenCalledWith('Environment variable for placeholder \'__unit_test_non_matching\' not found.');
+      });
+    });
+
     describe('has()', () => {
       beforeEach(() => {
         fs.readJSONSync.mockReturnValue({
@@ -184,5 +222,60 @@ describe('ConfigService', () => {
         });
       });
     });
+
+    describe('replacePlaceholders', () => {
+      let originalEnv: NodeJS.ProcessEnv;
+
+      beforeEach(() => {
+        jest.clearAllMocks();
+        originalEnv = { ...process.env };
+      });
+
+      afterEach(() => {
+        process.env = { ...originalEnv };
+      });
+
+      it('replaces a simple placeholder with an environment variable', () => {
+        process.env.TEST_VAR = 'value1';
+        const input = { key: 'Hello ${TEST_VAR}' };
+        const result = fixture['replacePlaceholders'](input);
+        expect(result.key).toBe('Hello value1');
+      });
+
+      it('leaves placeholder unchanged and logs error if env var is missing', () => {
+        delete process.env.MISSING_VAR;
+        const input = { key: 'Hello ${MISSING_VAR}' };
+        const result = fixture['replacePlaceholders'](input);
+        expect(result.key).toBe('Hello ${MISSING_VAR}');
+        expect(error).toHaveBeenCalledWith(expect.stringContaining('MISSING_VAR'));
+      });
+
+      it('replaces placeholders in nested objects and arrays', () => {
+        process.env.NESTED_VAR = 'nested';
+        const input = {
+          arr: ['${NESTED_VAR}', { inner: '${NESTED_VAR}' }],
+          obj: { deep: '${NESTED_VAR}' },
+        };
+        const result = fixture['replacePlaceholders'](input);
+        expect(result.arr[0]).toBe('nested');
+        expect((result.arr[1] as { inner: string }).inner).toBe('nested');
+        expect((result.obj as { deep: string }).deep).toBe('nested');
+      });
+
+      it('handles env. prefix in placeholders', () => {
+        process.env.PREFIX_VAR = 'prefix';
+        const input = { key: 'Value: ${env.PREFIX_VAR}' };
+        const result = fixture['replacePlaceholders'](input);
+        expect(result.key).toBe('Value: prefix');
+      });
+
+      it('replaces multiple placeholders in a single string', () => {
+        process.env.FIRST = 'one';
+        process.env.SECOND = 'two';
+        const input = { key: 'Values: ${FIRST}, ${SECOND}' };
+        const result = fixture['replacePlaceholders'](input);
+        expect(result.key).toBe('Values: one, two');
+      });
+    });
   });
 });

apps/generator-cli/src/app/services/config.service.ts

@@ -7,41 +7,41 @@ import { Command } from 'commander';
 @Injectable()
 export class ConfigService {
 
-  public readonly cwd = process.env.PWD || process.env.INIT_CWD || process.cwd()
+  public readonly cwd = process.env.PWD || process.env.INIT_CWD || process.cwd();
   public readonly configFile = this.configFileOrDefault();
 
   private configFileOrDefault() {
     this.program.parseOptions(process.argv);
     const conf = this.program.opts().openapitools;
 
-    if(!conf) {
+    if (!conf) {
       return path.resolve(this.cwd, 'openapitools.json');
     }
 
     return path.isAbsolute(conf) ? conf : path.resolve(this.cwd, conf);
   }
 
-  public get useDocker()  {
+  public get useDocker() {
     return this.get('generator-cli.useDocker', false);
   }
 
-  public get dockerImageName()  {
+  public get dockerImageName() {
     return this.get('generator-cli.dockerImageName', 'openapitools/openapi-generator-cli');
   }
 
   private readonly defaultConfig = {
-    $schema: './node_modules/@openapitools/openapi-generator-cli/config.schema.json',
+    $schema:
+      './node_modules/@openapitools/openapi-generator-cli/config.schema.json',
     spaces: 2,
     'generator-cli': {
       version: undefined,
     },
-  }
+  };
 
   constructor(
     @Inject(LOGGER) private readonly logger: LOGGER,
     @Inject(COMMANDER_PROGRAM) private readonly program: Command,
-  ) {
-  }
+  ) {}
 
   get<T = unknown>(path: string, defaultValue?: T): T {
     const getPath = (
@@ -110,9 +110,9 @@ export class ConfigService {
 
   private read() {
     const deepMerge = (
-      target: object,
+      target: Record<string, unknown>,
       source: object,
-    ): object => {
+    ): Record<string, unknown> => {
       if (!source || typeof source !== 'object') return target;
 
       const result = { ...target };
@@ -124,7 +124,7 @@ export class ConfigService {
             typeof source[key] === 'object' &&
             !Array.isArray(source[key])
           ) {
-            const value = (result[key] || {});
+            const value = (result[key] || {}) as Record<string, unknown>;
             result[key] = deepMerge(value, source[key]);
           } else {
             result[key] = source[key];
@@ -137,10 +137,57 @@ export class ConfigService {
 
     fs.ensureFileSync(this.configFile);
 
-    return deepMerge(
+    const config = deepMerge(
       this.defaultConfig,
       fs.readJSONSync(this.configFile, { throws: false, encoding: 'utf8' }),
     );
+
+    return this.replacePlaceholders(config);
+  }
+
+  private replacePlaceholders(config: Record<string, unknown>): Record<string, unknown> {
+    const replacePlaceholderInString = (inputString: string): string => {
+      return inputString.replace(/\${(.*?)}/g, (fullMatch, placeholderKey) => {
+        const environmentVariableKey = placeholderKey.startsWith('env.')
+          ? placeholderKey.substring(4)
+          : placeholderKey;
+
+        const environmentVariableValue = process.env[environmentVariableKey];
+
+        if (environmentVariableValue === undefined) {
+          this.logger.error(
+            `Environment variable for placeholder '${environmentVariableKey}' not found.`,
+          );
+          return fullMatch;
+        }
+
+        return environmentVariableValue;
+      });
+    };
+
+    const traverseConfigurationObject = (
+      configurationValue: unknown,
+    ): unknown => {
+      if (typeof configurationValue === 'string') {
+        return replacePlaceholderInString(configurationValue);
+      }
+      if (Array.isArray(configurationValue)) {
+        return configurationValue.map(traverseConfigurationObject);
+      }
+      if (configurationValue && typeof configurationValue === 'object') {
+        return Object.fromEntries(
+          Object.entries(configurationValue as Record<string, unknown>).map(
+            ([propertyKey, propertyValue]) => [
+              propertyKey,
+              traverseConfigurationObject(propertyValue),
+            ],
+          ),
+        );
+      }
+      return configurationValue;
+    };
+
+    return traverseConfigurationObject(config) as Record<string, unknown>;
   }
 
   private write(config) {