Configuring Log Level for Azure Functions

Question

I have an Azure Function App which has Application Insights configured. My functions have some LogTrace() messages in but they are not being captured by AppInsights. Do I have to configure a minimum loglevel somewhere?

Answer 1

Please take a look at this article on how to set log level for function v1 or v2.

In the file host.json, for the filed "Function", set its value to Trace. Then LogTrace() can be logged into application insights.

Sample host.json for Azure function v2, which can log trace messages to Application Insights:

{
  "version": "2.0",
  "logging": {
    "fileLoggingMode": "always",
    "logLevel": {
      "default": "Information",
      "Host.Results": "Error",
      "Function": "Trace",
      "Host.Aggregator": "Trace"
    }
  }
}

And if you publish your function app with visual studio, you can modify your host.json file as per the above before publishing.

And if you want to change the log level in azure portal, please follow this:

In Azure portal, navigate to your function app -> in the function app settings, make sure enable the Read/Write, then change log level to trace in the host.json.