Azure App Service Logging vs Application Insights Integration

Question

Azure App Service Logging vs Application Insights Integration

Cosmin Stirbu 171

Hello,

I'm trying to better understand when should we enable diagnostics logging for apps in Azure App Service (Monitoring ->App Service logs) and when it's enough to just configure Application Insights (Settings -> Application Insights).

This question was triggered by the following recommendations made by https://www.checkov.io/:

Thank you,
Cosmin

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Answer 1

Jaliya Udagedara 2,836 MVP Volunteer Moderator

Azure provides built-in diagnostics mechanism (App Service Logs) to assist with debugging an App Service app. There basically you will have to go through the logs to see what is happening.

Application Insights as the name suggests (Insights) provides a lot more features on top of just being able to view logs. Most importantly you can query the logs. Have a look at App Insights Overview.

To answer your question, I use App Service Logs when an App Service is failing to start, etc. For everything else, I use Application Insights.

Cosmin Stirbu 171 Reputation points

2021-08-02T16:35:14.703+00:00

How about in terms of the information being logged?

Is there any information that can be found by using App Service Logs and that's not available in App Insights?

Basically I'm interested if I can rely exclusively on App Insights or if I should also enabled App Service Logs.
Matthew Newbill 1 Reputation point

2021-10-01T18:52:05.57+00:00

@Cosmin Stirbu Did you ever get an answer to this? I'm asking myself the same question. I would rather not setup the app service logs retention/storage if I can get everything I need from App Insights.
Cosmin Stirbu 171 Reputation points

2021-10-03T08:06:36.357+00:00
@Matthew Newbill - after doing some more research this is what I've found:

App Service Application Logging is just another "logging provider" / "sink" (similar to Application Insights) for your ILogger logs. It can be added by turning it on in your Azure App Service and adding Microsoft.Extensions.Logging.AzureAppServices to your project (see https://learn.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-5.0#azure-app-service-1). We're using App Service Application Logging with Blob Support to log larger entries such as request / response payloads. These would be too big to be logged to AI and also it would be too costly.

App Service Web server logging are the logs from IIS - not particularly helpful though, they only contain minimum information about the requests made to your App Service. You can turn them on and see.

After doing some more research, it turns out the documentation from this link actually makes sense https://learn.microsoft.com/en-us/azure/app-service/troubleshoot-diagnostic-logs#overview
Matthew Newbill 1 Reputation point

2021-10-06T19:53:45.017+00:00

@Cosmin Stirbu Thank you so much for the reply! This was super helpful!
Josh Sutterfield 1 Reputation point

2023-10-06T15:09:00.2766667+00:00

I'm skeptical of this answer because it says "lots of features" and then the one specific feature emphasized is you can query the logs, not just view them. But that is already something you get (or I've certainly got in 2023) from as long as you turn on basic App service logging and query under the Monitoring section. Alas I'm seeing a lot of strange things with the logs captured and what's queryable vs. what is visibly logged otherwise so maybe ApplicationInsights does a better job of it while doing its many other things.

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Azure App Service Logging vs Application Insights Integration

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