Trellis.ServiceLevelIndicators 10.0.0-preview.21

Trellis.ServiceLevelIndicators

A .NET library for emitting Service Level Indicator (SLI) latency metrics in milliseconds via the standard System.Diagnostics.Metrics API. Use it to measure operation duration across any .NET application and attach dimensions such as operation name, customer, location, and outcome so the data is useful for SLO dashboards and alerts.

For ASP.NET Core applications, see Trellis.ServiceLevelIndicators.Asp.

When To Use This Package

Choose Trellis.ServiceLevelIndicators when you want to measure operations directly in application code, especially in console apps, worker services, background jobs, libraries, or shared business logic that should stay independent from ASP.NET Core.

If you want automatic measurement of ASP.NET Core endpoints, use Trellis.ServiceLevelIndicators.Asp instead.

Installation

dotnet add package Trellis.ServiceLevelIndicators

Quick Start

1. Register with OpenTelemetry

builder.Services.AddOpenTelemetry()
    .WithMetrics(metrics =>
    {
        metrics.AddServiceLevelIndicatorInstrumentation();
        metrics.AddOtlpExporter();
    });

If you supply a custom Meter in ServiceLevelIndicatorOptions, register that same meter with OpenTelemetry:

var sliMeter = new Meter("MyCompany.ServiceLevelIndicator");

builder.Services.AddOpenTelemetry()
    .WithMetrics(metrics =>
    {
        metrics.AddServiceLevelIndicatorInstrumentation(sliMeter);
        metrics.AddOtlpExporter();
    });

builder.Services.AddServiceLevelIndicator(options =>
{
    options.Meter = sliMeter;
    options.LocationId = ServiceLevelIndicator.CreateLocationId("public", "westus3");
    options.CustomerResourceId = "my-customer";
});

2. Configure options

builder.Services.AddServiceLevelIndicator(options =>
{
    options.LocationId = ServiceLevelIndicator.CreateLocationId("public", "westus3");
    options.CustomerResourceId = "my-customer";
});

3. Measure operations

Wrap any block of code in a using StartMeasuring scope:

void DoWork(ServiceLevelIndicator sli)
{
    using var op = sli.StartMeasuring("ProcessOrder");
    // Do work...
    op.SetOutcome(SliOutcome.Success);
}

You can also pass custom attributes:

var attribute = new KeyValuePair<string, object?>("Event", "OrderCreated");
using var op = sli.StartMeasuring("ProcessOrder", attribute);

Custom attribute names must be unique and must not reuse SLI-reserved tags such as CustomerResourceId, LocationId, Operation, Outcome, activity.status.code, http.request.method, or http.response.status.code.

Emitted Metrics

By default, a meter named Trellis.SLI emits the operation.duration histogram in milliseconds. If you configure ServiceLevelIndicatorOptions.Meter, metrics are emitted from that meter instead.

StartMeasuring(...) emits the following attributes when the returned MeasuredOperation is disposed:

Direct Record(...) calls emit CustomerResourceId, LocationId, Operation, Outcome, and any custom attributes supplied to the call. Without an explicit outcome, manual/background measurements default to Ignored.

Cardinality Guidance

Required tags must be stable and meaningful. Good values: tenant, subscription, environment, region, product tier, work-item type. Bad values: per-request GUIDs, timestamps, free-form user input, or raw emails when a stable object ID is available. The same rule applies to any custom attributes you add via MeasuredOperation.AddAttribute(...).

Disposal

ServiceLevelIndicator is a sealed IDisposable and is meant to be registered as a singleton — the DI container disposes it (and the Meter it created) at host shutdown, so applications never need to call Dispose() manually. If you supply your own Meter via ServiceLevelIndicatorOptions.Meter, you own its lifetime; SLI will not dispose it.

Key APIs

Further Reading

• Full documentation and samples
• Package selection and usage reference
• OpenTelemetry .NET