feat: add env var config layer for EurekaClient intervals — GH#4774

onboarding-enabler-nodejs/src/EurekaClient.js

@@ -62,6 +62,7 @@ import ConfigClusterResolver from './ConfigClusterResolver.js';
 import DnsClusterResolver from './DnsClusterResolver.js';
 import Logger from './Logger.js';
 import defaultConfig from './defaultConfig.js';
+import envConfig from './envConfig.js';
 import https from 'https';
 
 function noop() {}
@@ -113,7 +114,7 @@ export default class Eureka extends EventEmitter {
     const envYml = getYaml(path.join(cwd, `${filename}-${env}.yml`));
 
     // apply config overrides in appropriate order
-    this.config = merge({}, defaultConfig, defaultYml, envYml, config);
+    this.config = merge({}, defaultConfig, defaultYml, envYml, envConfig(), config);
 
     // Validate the provided the values we need:
     this.validateConfig(this.config);

onboarding-enabler-nodejs/src/envConfig.js

@@ -0,0 +1,55 @@
+/*
+ * This program and the accompanying materials are made available under the terms of the
+ * Eclipse Public License v2.0 which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-v20.html
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Copyright Contributors to the Zowe Project.
+ */
+
+// envConfig.js — maps EUREKA_CLIENT_* env vars to eureka config properties
+import Logger from './Logger.js';
+
+const logger = new Logger();
+
+const ENV_MAP = [
+  {
+    env: 'EUREKA_CLIENT_REGISTRYFETCHINTERVALSECONDS',
+    key: 'registryFetchInterval',
+    unit: 'seconds',
+  },
+  {
+    env: 'EUREKA_CLIENT_INSTANCEINFOREPLICATIONINTERVALSECONDS',
+    key: 'heartbeatInterval',
+    unit: 'seconds',
+  },
+  // Future: add entries here for circuit breaker properties (#4775)
+  // { env: 'EUREKA_CLIENT_MAXFAILURES',   key: 'maxFailures',   unit: 'milliseconds' },
+  // { env: 'EUREKA_CLIENT_COOLDOWNTIME',  key: 'cooldownTime',  unit: 'seconds' },
+  // { env: 'EUREKA_CLIENT_BACKOFFMAX',    key: 'backoffMax',    unit: 'seconds' },
+];
+
+function parsePositiveInt(envName) {
+  const raw = process.env[envName];
+  if (raw === undefined || raw === '') return undefined;
+  const parsed = parseInt(raw, 10);
+  if (isNaN(parsed) || parsed <= 0) {
+    const msg = `Invalid value for ${envName}: "${raw}". `
+      + 'Expected a positive integer. Using default.';
+    logger.warn(msg);
+    return undefined;
+  }
+  return parsed;
+}
+
+export default function envConfig() {
+  const result = { eureka: {} };
+  for (const { env, key, unit } of ENV_MAP) {
+    const value = parsePositiveInt(env);
+    if (value !== undefined) {
+      result.eureka[key] = unit === 'seconds' ? value * 1000 : value;
+    }
+  }
+  return result;
+}

onboarding-enabler-nodejs/src/index.js

@@ -75,7 +75,7 @@ function init() {
       };
     } else {
       throw new Error(
-          'Invalid TLS configuration: provide either p12File or certificate + keystore'
+        'Invalid TLS configuration: provide either p12File or certificate + keystore'
       );
     }
 

onboarding-enabler-nodejs/test/EurekaClient.test.js

@@ -1420,4 +1420,58 @@ describe('Eureka client', () => {
       expect(client.cache.app.THEAPP).to.have.length(0);
     });
   });
+
+  describe('env var configuration', () => {
+    const REGISTRY_ENV = 'EUREKA_CLIENT_REGISTRYFETCHINTERVALSECONDS';
+    const HEARTBEAT_ENV = 'EUREKA_CLIENT_INSTANCEINFOREPLICATIONINTERVALSECONDS';
+
+    afterEach(() => {
+      delete process.env[REGISTRY_ENV];
+      delete process.env[HEARTBEAT_ENV];
+    });
+
+    it('should override registryFetchInterval from env var', () => {
+      process.env[REGISTRY_ENV] = '60';
+      const client = new Eureka(makeConfig());
+      expect(client.config.eureka.registryFetchInterval).to.equal(60000);
+    });
+
+    it('should override heartbeatInterval from env var', () => {
+      process.env[HEARTBEAT_ENV] = '45';
+      const client = new Eureka(makeConfig());
+      expect(client.config.eureka.heartbeatInterval).to.equal(45000);
+    });
+
+    it('should let constructor config override env var', () => {
+      process.env[REGISTRY_ENV] = '60';
+      const client = new Eureka(makeConfig({
+        eureka: { registryFetchInterval: 9999 },
+      }));
+      expect(client.config.eureka.registryFetchInterval).to.equal(9999);
+    });
+
+    it('should use default values when env var is not set', () => {
+      const client = new Eureka(makeConfig());
+      expect(client.config.eureka.registryFetchInterval).to.equal(30000);
+      expect(client.config.eureka.heartbeatInterval).to.equal(30000);
+    });
+
+    it('should fall back to default on non-numeric env var', () => {
+      process.env[REGISTRY_ENV] = 'sixty';
+      sinon.spy(console, 'warn');
+      const client = new Eureka(makeConfig());
+      expect(client.config.eureka.registryFetchInterval).to.equal(30000);
+      expect(console.warn).to.have.been.calledWith(sinon.match('Invalid value for EUREKA_CLIENT_REGISTRYFETCHINTERVALSECONDS'));
+      console.warn.restore();
+    });
+
+    it('should fall back to default on zero env var', () => {
+      process.env[REGISTRY_ENV] = '0';
+      sinon.spy(console, 'warn');
+      const client = new Eureka(makeConfig());
+      expect(client.config.eureka.registryFetchInterval).to.equal(30000);
+      expect(console.warn).to.have.been.calledWith(sinon.match('Invalid value for EUREKA_CLIENT_REGISTRYFETCHINTERVALSECONDS'));
+      console.warn.restore();
+    });
+  });
 });