[QUERY] How to use a custom log processor

[AlexGlassman]

Library name and version

Azure.Monitor.OpenTelemetry.AspNetCore v1.1

Query/Question

I have implemented a custom log processor to obfuscate sensitive log data. As per the OpenTelemetry docs here, it looks something like this:

public class OTelSensitiveDataEnricher : BaseProcessor<LogRecord>
{
    private readonly IEnumerable<ISensitiveDataFilter> _sensitiveDataFilters;

    public OTelSensitiveDataEnricher(IEnumerable<ISensitiveDataFilter> sensitiveDataFilters)
    {
        _sensitiveDataFilters = sensitiveDataFilters;
    }

    public override void OnEnd(LogRecord logRecord)
    { 
       //use _sensitiveDataFilters to obfuscate data in logRecord 
    }
}

My issue is understanding how I can register this processor in my Program/StartUp.cs in conjunction with the Azure Monitor Distro, as the UseAzureMonitor() extension method handles log configuration behind the scenes, and it doesn't seem like there is a way to add a Log Processor in the same way as you can add a Trace Processor or Metrics Processor as shown in the docs.

Any help would be greatly appreciated. Thanks!

Environment

.NET 8

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @cijothomas @rajkumar-rangaraj @reyang @TimothyMothra @vishweshbankwar.

[TimothyMothra]

Hi @AlexGlassman, I've got some options for you.
Note that for either option you should add your Processor BEFORE calling UseAzureMonitor to place your custom Processor earlier in the chain.

Option 1. Call AddLogging and AddOpenTelemetry

builder.Services.AddLogging(logging =>
{
    logging.AddOpenTelemetry(builderOptions =>
    {
        builderOptions.AddProcessor(new MyCustomProcessor());
    });
});

builder.Services.AddOpenTelemetry().UseAzureMonitor();

Option 2. Experimental Api: ConfigureOpenTelemetryLoggerProvider

As of today, this API is currently only available in beta versions of OpenTelemetry.

You can watch the OpenTelemetry dotnet repo to see when this API is stablized: open-telemetry/opentelemetry-dotnet#5442

builder.Services.ConfigureOpenTelemetryLoggerProvider(builder => builder.AddProcessor<MyCustomProcessor>());
builder.Services.AddOpenTelemetry().UseAzureMonitor();

[AlexGlassman]

Thanks @TimothyMothra! Option 1 worked a treat; I did initially think about this approach but erroneously assumed calling UseAzureMonitor() would override whatever custom processors were configured before it. This is a production workload so went with the more stable option, but will keep my eyes peeled for ConfigureOpenTelemetryLoggerProvider coming out of beta.

Thanks again!