In a previous article I wrote about using middleware to add concurrency keys into an Asp.Net Core project. I’d like to extend that and show how to integrate a logging platform with concurrency keys. Our .Net Core logging framework of choice is Serilog. They have great integration with common logging protocols, and there stuff is very extensible.
Serilog allows a developer to inject properties into the LogContext. The LogContext This allows us to take properties and map them to the log templates. First, we’ll create a piece of middleware to push the concurrency key into the LogContext for Serilog.
public class SerilogConcurrencyMiddleware
{
private readonly RequestDelegate next;
public SerilogConcurrencyMiddleware(RequestDelegate next)
{
this.next = next;
}
public Task Invoke(HttpContext context)
{
var key = context.Request.Headers["X-Concurrency-Key"];
if (string.IsNullOrWhiteSpace(key))
return next(context);
using (LogContext.PushProperty("ConcurrencyKey", key.FirstOrDefault()))
{
return next(context);
}
}
}
The code is not complete without the tests. Make sure you include “Serilog.Sinks.TestCorrelator” NuGet package in your test project. This allows verifying the information in the LogContext.
public class SerilogConcurrencyMiddlewareTests
{
public SerilogConcurrencyMiddlewareTests()
{
}
private HttpContext BuildContext()
{
Log.Logger = new LoggerConfiguration()
.Enrich.FromLogContext()
.WriteTo.TestCorrelator().CreateLogger();
var context = new DefaultHttpContext();
return context;
}
private async Task<LogEvent> BuildAndRunMiddleware(HttpContext context)
{
LogEvent loggedEvent = null;
var middleware = new SerilogConcurrencyMiddleware(next: (inner) =>
{
// Need to create a context specifically for this
// request or properties disappear or move to other
// unit tests (bad).
using (TestCorrelator.CreateContext())
{
Log.Information("{ConcurrencyKey} Woo!");
loggedEvent = TestCorrelator
.GetLogEventsFromCurrentContext()
.ToList().FirstOrDefault();
return Task.FromResult(0);
}
});
await middleware.Invoke(context);
return loggedEvent;
}
[Fact]
public async Task Invoke_NoHeader_DoesntThrowException()
{
var context = BuildContext();
var result = await BuildAndRunMiddleware(context);
Assert.True(result.Properties.Count < 1);
}
[Fact]
public async Task Invoke_KeyHeader_LogHasKey()
{
var context = BuildContext();
context.Request.Headers.Add("X-Concurrency-Key", "Bacon");
var result = await BuildAndRunMiddleware(context);
Assert.True(result.Properties.Count > 0);
Assert.True(result.Properties.ContainsKey("ConcurrencyKey"));
Assert.Contains("Bacon", result.RenderMessage());
}
}
Once there is middleware and tests in place, simply add the middleware to the application pipeline.
app.UseMiddleware<SerilogConcurrencyMiddleware>();
Here is an example Serilog template in the appsettings.json to display the concurrency keys.
"Serilog": {
"Using": [
"Serilog.Sinks.Console"
],
"MinimumLevel": "Warning",
"WriteTo": [
{
"Name": "Console",
"Args":
{
"outputTemplate": "{Timestamp:MMM d HH:mm:ss} {ConcurrencyKey} {Level:u4}: {Message}{NewLine}{Exception}"
}
}
],
"Enrich": ["FromLogContext"],
"Properties": {
"Application": "MyAwesomeApplication"
}
}
I hope this helps.
I'm currently the Co-Founder / CTO with an amazing team at Rentler. We build property management software for independant landlords and their renters using a plethora of technologies.
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