Fixes and enhancements for handling multiple discovery servers

CHANGELOG.md

@@ -5,6 +5,7 @@ This repo is part of the app-server Zowe Component, and the change logs here may
 
 ## 2.14.0
 - Bugfix: App-server would not correctly detect when it was running in a high-availability configuration environment.
+- Bugfix: App-server could not load when multiple discovery servers were present and the app-server was unable to reach the first one specified. Now, the app-server will iterate through the list of servers until an accessible one is reached.
 
 ## 2.13.0
 - Added support for using zowe.network and components.app-server.zowe.network to set listener IP and TLS properties including max and min version, ciphers, and ECDH curves. (#511)

lib/apiml.js

@@ -77,9 +77,9 @@ const MEDIATION_LAYER_INSTANCE_DEFAULTS = (zluxProto, zluxHostname, zluxPort) =>
   }
 }};
 
-function ApimlConnector({ hostName, port, isHttps, discoveryHost,
+function ApimlConnector({ hostName, port, isHttps, discoveryUrls,
     discoveryPort, tlsOptions, eurekaOverrides }) {
-  Object.assign(this, { hostName, port, isHttps, discoveryHost,
+  Object.assign(this, { hostName, port, isHttps, discoveryUrls,
     discoveryPort, tlsOptions, eurekaOverrides });
   this.vipAddress = hostName;
 }
@@ -110,23 +110,13 @@ ApimlConnector.prototype = {
     const end = Date.now() + timer;
 
     return new Promise((resolve, reject) => {
-      const options = Object.assign({
-        host: this.discoveryHost,
-        port: this.discoveryPort,
-        method: 'GET',
-        path: `/eureka/apps/${serviceName}`,
-        headers: {'accept':'application/json'}
-      }, this.tlsOptions);
-
-      if (!this.tlsOptions.rejectUnauthorized) {
-        //Keeping these certs causes an openssl error 46, unknown cert error in a dev environment
-        delete options.cert;
-        delete options.key;
-      } //else, apiml expects a cert and will give a 403.
+      const optionsArray = this.getRequestOptionsArray('GET', `/eureka/apps/${serviceName}`);
+      let optionsIndex = 0;
 
       const issueRequest = () => {
+        const options = optionsArray[optionsIndex];
         if (Date.now() > end) {
-          log.warn(`ZWED0045`, this.discoveryHost, this.discoveryPort);
+          log.warn(`ZWED0045W`, this.discoveryHost, this.discoveryPort);
           return reject(new Error(`Call timeout when fetching agent status from APIML`));
         }
 
@@ -156,7 +146,9 @@ ApimlConnector.prototype = {
           reject(new Error(`Call timeout when fetching agent status from APIML`));
         });
         req.on('error', (error) => {
-          log.warn("APIML query error:", error.message);
+          log.warn("ZWED0180W", options.host, options.port, error.message);
+          //
+          optionsIndex = (optionsIndex+1) % optionsArray.length;
           setTimeout(issueRequest, AGENT_CHECK_RECONNECT_DELAY);
         });
         req.end();
@@ -249,8 +241,7 @@ ApimlConnector.prototype = {
     }
     log.debug("ZWED0144I", JSON.stringify(zluxProxyServerInstanceConfig, null, 2)); //log.debug("zluxProxyServerInstanceConfig: " 
         //+ JSON.stringify(zluxProxyServerInstanceConfig, null, 2))
-    const defaultUrl = `https://${this.discoveryHost}:${this.discoveryPort}/eureka/apps`;
-    const serviceUrls = this.getServiceUrls(defaultUrl);
+    const serviceUrls = this.getServiceUrls();
     zluxProxyServerInstanceConfig.eureka.serviceUrls = { default: serviceUrls };
     log.info(`ZWED0020I`, serviceUrls.join(',')); //log.info(`Registering at ${url}...`);
     log.debug("ZWED0145I", JSON.stringify(zluxProxyServerInstanceConfig)); //log.debug(`zluxProxyServerInstanceConfig ${JSON.stringify(zluxProxyServerInstanceConfig)}`)
@@ -285,17 +276,29 @@ ApimlConnector.prototype = {
     });
   },
 
-  getServiceUrls(defaultUrl) {
-    const discoveryServiceList = process.env['ZWE_DISCOVERY_SERVICES_LIST'] || '';
-    const serviceUrls = discoveryServiceList
-      .split(',')
-      .map(url => url.trim())
-      .filter(url => url.length > 0)
-      .map(url => url + (url.endsWith('/') ? '' : '/') + 'apps');
-    if (serviceUrls.length === 0) {
-      serviceUrls.push(defaultUrl);
-    }
-    return serviceUrls;
+  getServiceUrls() {
+    return this.discoveryUrls.map(url => url + (url.endsWith('/') ? '' : '/') + 'apps');
+  },
+
+  getRequestOptionsArray(method, path) {
+    return this.discoveryUrls.map((url)=>{
+      //in the form of https://host:port/eureka/, trim from https:// and following slash.
+      const hostAndPort = url.substring(8, url.indexOf('/', 8)).split(':');
+      const options = Object.assign({
+        host: hostAndPort[0],
+        port: hostAndPort[1],
+        method: method,
+        path: path,
+        headers: {'accept':'application/json'}
+      }, this.tlsOptions);
+
+      if (!this.tlsOptions.rejectUnauthorized) {
+        //Keeping these certs causes an openssl error 46, unknown cert error in a dev environment
+        delete options.cert;
+        delete options.key;
+      } //else, apiml expects a cert and will give a 403.
+      return options;
+    });
   }
 
   /*

lib/assets/i18n/log/messages_en.json

@@ -307,6 +307,7 @@
   "ZWED0177W":"Unable to load %s for '%s' into config",
   "ZWED0178W":"Skipping authentication plugin %s because it's not HA compatible",
   "ZWED0179W":"Unable to retrieve the list of certificate authorities from the keyring=%s owner=%s Error: %s",
+  "ZWED0180W":"Failed to query discovery server (%s:%s) for agent access: %s",
 
   "ZWED0001E":"RESERVED: Error: %s",
   "ZWED0002E":"Could not stop language manager for types=%s",

lib/index.js

@@ -219,8 +219,7 @@ Server.prototype = {
           hostName: webAppOptions.hostname,
           port: this.port,
           isHttps: util.isServerHttps(this.zoweConfig),
-          discoveryHost: apimlConfig.server.hostname,
-          discoveryPort: apimlConfig.server.port,
+          discoveryUrls: apimlConfig.server.discoveryUrls || [`https://${apimlConfig.server.hostname}:${apimlConfig.server.port}/eureka/`],
           tlsOptions: this.tlsOptions,
           eurekaOverrides: apimlConfig.eureka
         });
@@ -236,7 +235,7 @@ Server.prototype = {
          && this.componentConfig.agent.mediationLayer.serviceName
          && this.componentConfig.node.mediationLayer.server?.gatewayPort) {
         //at this point, we expect zss to also be attached to the mediation layer, so lets adjust.
-        webAppOptions.proxiedHost = apimlConfig.server.hostname;
+        webAppOptions.proxiedHost = apimlConfig.server.gatewayHostname;
         webAppOptions.proxiedPort = this.componentConfig.node.mediationLayer.server.gatewayPort;
         if (firstWorker) {
           yield this.apiml.checkAgent(this.componentConfig.agent.handshakeTimeout,

lib/webapp.js

@@ -268,7 +268,8 @@ function getUserEnv(rbac, zoweConfig){
           "ZWED_node_mediationLayer_enabled": nodeConfig.mediationLayer.enabled,
 
           "ZWED_node_mediationLayer_server_hostname": nodeConfig.mediationLayer.server.hostname,
-
+          "ZWED_node_mediationLayer_server_gatewayHostname": nodeConfig.mediationLayer.server.gatewayHostname,
+
           //may diverge from above
           "ZWE_EXTERNAL_HOSTS": process.env.ZWE_EXTERNAL_HOSTS ? process.env.ZWE_EXTERNAL_HOSTS : zoweConfig.zowe.externalDomains.join(','),
           "ZWE_zowe_externalDomains": zoweConfig.zowe.externalDomains.join(','),

plugins/sso-auth/lib/apimlHandler.js

@@ -55,7 +55,7 @@ class ApimlHandler {
   constructor(pluginDef, pluginConf, serverConf, context) {
     this.logger = context.logger;    
     this.apimlConf = serverConf.node.mediationLayer.server;    
-    this.gatewayUrl = `https://${this.apimlConf.hostname}:${this.apimlConf.gatewayPort}`;
+    this.gatewayUrl = `https://${this.apimlConf.gatewayHostname}:${this.apimlConf.gatewayPort}`;
     this.httpsAgent = new https.Agent(context.tlsOptions);
   }
 
@@ -66,7 +66,7 @@ class ApimlHandler {
       }
       const gatewayUrl = this.gatewayUrl;
       const options = {
-        hostname: this.apimlConf.hostname,
+        hostname: this.apimlConf.gatwayHostname,
         port: this.apimlConf.gatewayPort,
 //TODO uncertainty about using apicatalog route instead of something part of the gateway itself
         path: '/apicatalog/api/v1/auth/logout',
@@ -194,7 +194,7 @@ class ApimlHandler {
     }
 
     return {
-      hostname: this.apimlConf.hostname,
+      hostname: this.apimlConf.gatewayHostname,
       port: this.apimlConf.gatewayPort,
       path: path,
       method: method,

plugins/sso-auth/lib/ssoAuth.js

@@ -18,7 +18,7 @@ const apimlHandlerFactory = require('./apimlHandler');
 function doesApimlExist(serverConf) {
   return ((serverConf.node.mediationLayer !== undefined)
     && (serverConf.node.mediationLayer.server !== undefined)
-    && (serverConf.node.mediationLayer.server.hostname !== undefined)
+    && (serverConf.node.mediationLayer.server.gatewayHostname !== undefined)
     && (serverConf.node.mediationLayer.server.gatewayPort !== undefined)
     && (serverConf.node.mediationLayer.server.port !== undefined)
     && (serverConf.node.mediationLayer.enabled == true))