[main] Adding round robin retry for snippet script src loading

AISKU/src/Snippet.ts

@@ -15,4 +15,5 @@ export interface Snippet {
  queue?: Array<() => void>;
  sv?: string;
  version?: number;
+ cr?: boolean; // cdn retry would be proceed if ture
 }

tools/applicationinsights-web-snippet/src/snippet.ts

@@ -98,7 +98,7 @@ declare var cfg:ISnippetConfig;
  let ingest = conString[strIngestionendpoint];
  let endpointUrl = ingest ? ingest + "/v2/track" : aiConfig.endpointUrl; // only add /v2/track when from connectionstring
 
- let message = "SDK LOAD Failure: Failed to load Application Insights SDK script (See stack for details)";
+ let message = "SDK LOAD Failure: Failed to load Application Insights SDK script via " + targetSrc + " (See stack for details)";
  let evts:IEnvelope[] = [];
  evts.push(_createException(iKey, message, targetSrc, endpointUrl));
  evts.push(_createInternal(iKey, message, targetSrc, endpointUrl));
@@ -183,6 +183,19 @@ declare var cfg:ISnippetConfig;
 
  return envelope;
  }
+
+ let domainRetryIndex = -1;
+ let domains = [
+ "js.monitor.azure.com",
+ "js.cdn.applicationinsights.io",
+ "js.cdn.monitor.azure.com",
+ "js0.cdn.applicationinsights.io",
+ "js0.cdn.monitor.azure.com",
+ // "js1.cdn.monitor.azure.com",
+ "js2.cdn.applicationinsights.io",
+ "js2.cdn.monitor.azure.com",
+ "az416426.vo.msecnd.net"
+ ]
 
  // Assigning these to local variables allows them to be minified to save space:
  let targetSrc : string = (aiConfig as any)["url"] || cfg.src
@@ -194,12 +207,24 @@ declare var cfg:ISnippetConfig;
  });
  // let message = "Load Version 2 SDK instead to support IE"; // where to report this error?
  }
+ if (appInsights.cr){
+ for (var i = 0; i < domains.length; i++){
+ if (targetSrc.indexOf(domains[i])){
+ domainRetryIndex = 0;
+ break;
+ }
+ }
  const _handleError = (evt?: any) => {
- loadFailed = true;
  appInsights.queue = []; // Clear the queue
  if (!handled) {
- handled = true;
- _reportFailure(targetSrc);
+ // start retry
+ if (domainRetryIndex > 0 && domainRetryIndex < domains.length){
+ theScript = _createScript("https://" + domains[domainRetryIndex] + "/scripts/b/ai.2.min.js");
+ } else {
+ handled = true;
+ loadFailed = true;
+ _reportFailure(targetSrc);
+ }
  }
  }
 
@@ -213,11 +238,12 @@ declare var cfg:ISnippetConfig;
  }
  }, 500);
  }
+ loadFailed = false;
  }
 
- const _createScript = () => {
+ const _createScript = (src: string) => {
  let scriptElement : HTMLElement = doc.createElement(scriptText);
- (scriptElement as any)["src"] = targetSrc;
+ (scriptElement as any)["src"] = src;
  // Allocate Cross origin only if defined and available
  let crossOrigin = cfg[strCrossOrigin];
  if ((crossOrigin || crossOrigin === "") && scriptElement[strCrossOrigin] != strUndefined) {
@@ -235,7 +261,8 @@ declare var cfg:ISnippetConfig;
  return scriptElement;
  }
 
- let theScript = _createScript();
+ let theScript = _createScript(targetSrc);
+
  if (cfg.ld && cfg.ld < 0) {
  // if user wants to append tag to document head, blocking page load
  let headNode = doc.getElementsByTagName("head")[0];