Blazor Client Side (WASM) Application Insights

Question

Does Application Insights SDK work for Blazor WASM?

I'm trying connect my application but it doesn't send any metrics. Even when instantiating TelemetryClient it's simply hanging.

Answer 1

Unlike Blazor Server-side, you can't just add a singleton into IoC and then inject it to pages. The first thing I tried was this way too! I know, that should be the way... Blazor team needs to handle this behind the scene I think.

But anyway, here is what you should do:

Our approach will assume that we will use the Application Insight javascript SDK.

Copy the snippet mentioned on here: https://docs.microsoft.com/en-us/azure/azure-monitor/app/javascript#snippet-based-setup

(if you are too lazy, find below)

<script type="text/javascript">
!function(T,l,y){var S=T.location,u="script",k="instrumentationKey",D="ingestionendpoint",C="disableExceptionTracking",E="ai.device.",I="toLowerCase",b="crossOrigin",w="POST",e="appInsightsSDK",t=y.name||"appInsights";(y.name||T[e])&&(T[e]=t);var n=T[t]||function(d){var g=!1,f=!1,m={initialize:!0,queue:[],sv:"4",version:2,config:d};function v(e,t){var n={},a="Browser";return n[E+"id"]=a[I](),n[E+"type"]=a,n["ai.operation.name"]=S&&S.pathname||"_unknown_",n["ai.internal.sdkVersion"]="javascript:snippet_"+(m.sv||m.version),{time:function(){var e=new Date;function t(e){var t=""+e;return 1===t.length&&(t="0"+t),t}return e.getUTCFullYear()+"-"+t(1+e.getUTCMonth())+"-"+t(e.getUTCDate())+"T"+t(e.getUTCHours())+":"+t(e.getUTCMinutes())+":"+t(e.getUTCSeconds())+"."+((e.getUTCMilliseconds()/1e3).toFixed(3)+"").slice(2,5)+"Z"}(),iKey:e,name:"Microsoft.ApplicationInsights."+e.replace(/-/g,"")+"."+t,sampleRate:100,tags:n,data:{baseData:{ver:2}}}}var h=d.url||y.src;if(h){function a(e){var t,n,a,i,r,o,s,c,p,l,u;g=!0,m.queue=[],f||(f=!0,t=h,s=function(){var e={},t=d.connectionString;if(t)for(var n=t.split(";"),a=0;a<n.length;a++){var i=n[a].split("=");2===i.length&&(e[i[0][I]()]=i[1])}if(!e[D]){var r=e.endpointsuffix,o=r?e.location:null;e[D]="https://"+(o?o+".":"")+"dc."+(r||"services.visualstudio.com")}return e}(),c=s[k]||d[k]||"",p=s[D],l=p?p+"/v2/track":config.endpointUrl,(u=[]).push((n="SDK LOAD Failure: Failed to load Application Insights SDK script (See stack for details)",a=t,i=l,(o=(r=v(c,"Exception")).data).baseType="ExceptionData",o.baseData.exceptions=[{typeName:"SDKLoadFailed",message:n.replace(/\./g,"-"),hasFullStack:!1,stack:n+"\nSnippet failed to load ["+a+"] -- Telemetry is disabled\nHelp Link: https://go.microsoft.com/fwlink/?linkid=2128109\nHost: "+(S&&S.pathname||"_unknown_")+"\nEndpoint: "+i,parsedStack:[]}],r)),u.push(function(e,t,n,a){var i=v(c,"Message"),r=i.data;r.baseType="MessageData";var o=r.baseData;return o.message='AI (Internal): 99 message:"'+("SDK LOAD Failure: Failed to load Application Insights SDK script (See stack for details) ("+n+")").replace(/\"/g,"")+'"',o.properties={endpoint:a},i}(0,0,t,l)),function(e,t){if(JSON){var n=T.fetch;if(n&&!y.useXhr)n(t,{method:w,body:JSON.stringify(e),mode:"cors"});else if(XMLHttpRequest){var a=new XMLHttpRequest;a.open(w,t),a.setRequestHeader("Content-type","application/json"),a.send(JSON.stringify(e))}}}(u,l))}function i(e,t){f||setTimeout(function(){!t&&m.core||a()},500)}var e=function(){var n=l.createElement(u);n.src=h;var e=y[b];return!e&&""!==e||"undefined"==n[b]||(n[b]=e),n.onload=i,n.onerror=a,n.onreadystatechange=function(e,t){"loaded"!==n.readyState&&"complete"!==n.readyState||i(0,t)},n}();y.ld<0?l.getElementsByTagName("head")[0].appendChild(e):setTimeout(function(){l.getElementsByTagName(u)[0].parentNode.appendChild(e)},y.ld||0)}try{m.cookie=l.cookie}catch(p){}function t(e){for(;e.length;)!function(t){m[t]=function(){var e=arguments;g||m.queue.push(function(){m[t].apply(m,e)})}}(e.pop())}var n="track",r="TrackPage",o="TrackEvent";t([n+"Event",n+"PageView",n+"Exception",n+"Trace",n+"DependencyData",n+"Metric",n+"PageViewPerformance","start"+r,"stop"+r,"start"+o,"stop"+o,"addTelemetryInitializer","setAuthenticatedUserContext","clearAuthenticatedUserContext","flush"]),m.SeverityLevel={Verbose:0,Information:1,Warning:2,Error:3,Critical:4};var s=(d.extensionConfig||{}).ApplicationInsightsAnalytics||{};if(!0!==d[C]&&!0!==s[C]){method="onerror",t(["_"+method]);var c=T[method];T[method]=function(e,t,n,a,i){var r=c&&c(e,t,n,a,i);return!0!==r&&m["_"+method]({message:e,url:t,lineNumber:n,columnNumber:a,error:i}),r},d.autoExceptionInstrumented=!0}return m}(y.cfg);(T[t]=n).queue&&0===n.queue.length&&n.trackPageView({})}(window,document,{
src: "https://az416426.vo.msecnd.net/scripts/b/ai.2.min.js", // The SDK URL Source
//name: "appInsights", // Global SDK Instance name defaults to "appInsights" when not supplied
//ld: 0, // Defines the load delay (in ms) before attempting to load the sdk. -1 = block page load and add to head. (default) = 0ms load after timeout,
//useXhr: 1, // Use XHR instead of fetch to report failures (if available),
//crossOrigin: "anonymous", // When supplied this will add the provided value as the cross origin attribute on the script tag 
cfg: { // Application Insights Configuration
    instrumentationKey: "YOUR_INSTRUMENTATION_KEY_GOES_HERE"
    /* ...Other Configuration Options... */
}});
</script>

Copy above code into index.html in <head>, ideally before link and script tags

Next, you need to inject IJSRuntime to call JavaScript methods from .Net code.

Inject it like this on top of the page:

@inject IJSRuntime _jsRuntime

Then you can call whatever Application Insight methods you want via like this:

await _jsRuntime.InvokeVoidAsync("appInsights.trackPageView");

You can find the full list of methods for AI JS SDK here:

https://github.com/microsoft/ApplicationInsights-JS/blob/master/API-reference.md

if you don't want to deal with JSRuntime, @IvanJosipovic created a BlazorApplicationInsight library that wraps everything for you.

Simply follow the instructions on his readme file: https://github.com/IvanJosipovic/BlazorApplicationInsights

Sample telemetry results from my Blazor WebAssembly project:

Hope it helps 🤞