feat: introduce feature toggles (#1121)

feat: introduce feature toggles

.env.example

@@ -22,3 +22,16 @@
 # FLOGO_LIB_VERSION=latest
 ## only if FLOGO_LIB_VERSION is not set:
 # FLOGO_WEB_LIB_VERSION=latest
+
+### Feature toggles
+### Enable/Disable features
+### Syntax: FLOGO_FEATURES_<name of the flag
+
+## Enable a flag
+# FLOGO_FEATURES_STREAMS=1
+
+### Disable a flag
+### Give an empty value to disable the flag
+### NOTE these values are always considered as strings and providing a value different than the empty string will be
+### considered as a truthy value. This means that values like false, 'false' or 0 won't work.
+# FLOGO_FEATURES_FLAG_X=''

apps/client/src/flogo/flogo.module.ts

@@ -14,6 +14,7 @@ import {
   FLOGO_VERSION,
   HOSTNAME,
   initializer,
+  FEATURE_TOGGLES_APP_INITIALIZER,
 } from '@flogo-web/lib-client/core';
 import { LanguageService, createTranslateLoader } from '@flogo-web/lib-client/language';
 import { ContribInstallerService } from '@flogo-web/lib-client/contrib-installer';
@@ -76,6 +77,7 @@ import { resourcePlugins } from '../plugins';
       deps: [TranslateService],
       multi: true,
     },
+    FEATURE_TOGGLES_APP_INITIALIZER,
     { provide: APP_BASE_HREF, useValue: '/' },
     appRoutingProviders,
     ContribInstallerService,

apps/server/src/api/v2/index.ts

@@ -26,5 +26,10 @@ export function createRouter(container: Container): Router {
   mountServices(router);
   mountEngine(router);
   mountTestRunner(router);
+
+  router.get('/_/features', context => {
+    context.body = config.features;
+  });
+
   return router;
 }

apps/server/src/config/app-config.js

@@ -1,6 +1,8 @@
 import * as path from 'path';
 
 import './load-env';
+import { parseFeatureToggles } from './parse-features-toggles';
+const features = parseFeatureToggles(process.env);
 
 const rootPath = path.resolve(__dirname, '..');
 const PUBLIC_DIR =
@@ -41,6 +43,7 @@ const config = {
   logsPath: path.join(LOCAL_DIR, 'logs'),
   logLevel,
   localPath: LOCAL_DIR,
+  features,
   defaultAppJsonPath: path.join(rootPath, 'config', 'sample-app.json'),
   defaultFlogoDescriptorPath:
     process.env.FLOGO_WEB_DEFAULT_DESCRIPTOR ||

apps/server/src/config/index.ts

@@ -0,0 +1,3 @@
+export { config } from './app-config';
+
+export { isFeatureEnabled } from './is-feature-enabled';

apps/server/src/config/is-feature-enabled.ts

@@ -0,0 +1,5 @@
+import { config } from './app-config';
+
+export function isFeatureEnabled(featureName: string) {
+  return config.features && config.features[featureName];
+}

apps/server/src/config/parse-features-toggles.ts

@@ -0,0 +1,13 @@
+const FEATURES_PREFIX = 'FLOGO_FEATURES_';
+const FEATURES_PREFIX_LENGTH = FEATURES_PREFIX.length;
+
+function featuresReducer(features, [envKey, envValue]: [string, any]) {
+  if (envKey.startsWith(FEATURES_PREFIX)) {
+    features[envKey.slice(FEATURES_PREFIX_LENGTH)] = envValue;
+  }
+  return features;
+}
+
+export function parseFeatureToggles(fromEnv: NodeJS.ProcessEnv) {
+  return Object.entries(fromEnv).reduce(featuresReducer, {});
+}

libs/lib-client/core/src/services/feature-toggles.ts

@@ -0,0 +1,36 @@
+import { Injectable, APP_INITIALIZER, FactoryProvider } from '@angular/core';
+import { tap, catchError } from 'rxjs/operators';
+import { EMPTY } from 'rxjs';
+import { RestApiService } from './restapi';
+
+@Injectable({ providedIn: 'root' })
+export class FeatureToggleService {
+  features: { [featureName: string]: any };
+
+  isFeatureEnabled(featureName: string) {
+    return this.features && !!this.features[featureName];
+  }
+}
+
+// needed to be exported because of AoT
+export function featureToggleServiceFactory(
+  apiService: RestApiService,
+  featureService: FeatureToggleService
+) {
+  return () => {
+    return apiService
+      .get('_/features')
+      .pipe(
+        tap(features => (featureService.features = features)),
+        catchError(() => EMPTY)
+      )
+      .toPromise();
+  };
+}
+
+export const FEATURE_TOGGLES_APP_INITIALIZER: FactoryProvider = {
+  provide: APP_INITIALIZER,
+  useFactory: featureToggleServiceFactory,
+  deps: [RestApiService, FeatureToggleService],
+  multi: true,
+};

libs/lib-client/core/src/services/index.ts

@@ -12,3 +12,5 @@ export * from './service-url-config.model';
 export * from './app-resource.service';
 export * from './log.service';
 export * from './activated-resource-route';
+
+export * from './feature-toggles';