WARNING: This project is a work in progress and not yet ready for production

OpenTracing gRPC Instrumentation

OpenTracing instrumentation for gRPC.

Installation

Install the NuGet package:

Install-Package OpenTracing.Contrib.Grpc

Usage

Server

• Instantiate tracer
• Create a ServerTracingInterceptor
• Intercept a service

using Grpc.Core;
using Grpc.Core.Interceptors;
using OpenTracing.Contrib.Grpc;

    public class YourServer {

        private readonly string host;
        private readonly int port;
        private readonly Server server;
        private readonly Tracer tracer;

        private void Start() {
            ServerTracingInterceptor tracingInterceptor = new ServerTracingInterceptor(this.tracer);

            Server server = new Server
            {
                Ports = { new ServerPort(this.host, this.port, ServerCredentials.Insecure) },
                Services = { SomeService.BindService(new SomeServiceImpl()).Intercept(tracingInterceptor) }
            };
            server.Start();
        }
    }

Client

• Instantiate a tracer
• Create a ClientTracingInterceptor
• Intercept the client channel

using Grpc.Core;
using Grpc.Core.Interceptors;
using OpenTracing.Contrib.Grpc;

    public class YourClient {

        private readonly Channel channel;
        private readonly Tracer tracer;
        private readonly SomeServiceClient client;

        public YourClient(string host, int port) {
            this.channel = new Channel(host, port, ChannelCredentials.Insecure);

            ClientTracingInterceptor tracingInterceptor = new ClientTracingInterceptor(this.tracer);
            this.client = new SomeService.SomeServiceClient(this.channel.Intercept(tracingInterceptor));
        }
    }

Server Tracing

A ServerTracingInterceptor uses default settings, which you can override by creating it using a ServerTracingInterceptor.Builder.

• WithOperationName(IOperationNameConstructor operationName): Define how the operation name is constructed for all spans created for this intercepted server. Default is the name of the RPC method. More details in the Operation Name section.
• WithStreaming(): Logs to the server span whenever a message is received. Note: This package supports streaming but has not been rigorously tested. If you come across any issues, please let us know.
• WithVerbosity(): Logs to the server span additional events, such as message received, headers received and call complete. Default only logs if a call is cancelled.
• WithTracedAttributes(params ServerRequestAttribute[] attrs): Sets tags on the server span in case you want to track information about the RPC call.

Example

ServerTracingInterceptor tracingInterceptor = new ServerTracingInterceptor
    .Builder(tracer)
    .WithStreaming()
    .WithVerbosity()
    .WithOperationName(new PrefixOperationNameConstructor("Server"))
    .WithTracedAttributes(ServerTracingConfiguration.RequestAttribute.Headers,
        ServerTracingConfiguration.RequestAttribute.MethodType)
    .Build();

Client Tracing

A ClientTracingInterceptor also has default settings, which you can override by creating it using a ClientTracingInterceptor.Builder.

• WithOperationName(IOperationNameConstructor operationName): Define how the operation name is constructed for all spans created for this intercepted client. Default is the name of the RPC method. More details in the Operation Name section.
• WithStreaming(): Logs to the client span whenever a message is sent or a response is received. Note: This package supports streaming but has not been rigorously tested. If you come across any issues, please let us know.
• WithVerbosity(): Logs to the client span additional events, such as call started, message sent, headers received, response received, and call complete. Default only logs if a call is cancelled.
• WithTracedAttributes(params ClientRequestAttribute[] attrs): Sets tags on the client span in case you want to track information about the RPC call.

Example

public class CustomOperationNameConstructor : IOperationNameConstructor
{
    public string ConstructOperationName<TRequest, TResponse>(Method<TRequest, TResponse> method)
    {
        // construct some operation name from the method descriptor
    }
}

ClientTracingInterceptor tracingInterceptor = new ClientTracingInterceptor
    .Builder(tracer)
    .WithStreaming()
    .WithVerbosity()
    .WithOperationName(new CustomOperationNameConstructor())
    .WithTracingAttributes(ClientTracingConfiguration.RequestAttribute.AllCallOptions,
        ClientTracingConfiguration.ClientRequestAttribute.Headers)
    .Build();

Current Span Context

In your server request handler, you can access the current active span for that request by calling

Span span = tracer.ActiveSpan;

This is useful if you want to manually set tags on the span, log important events, or create a new child span for internal units of work. You can also use this key to wrap these internal units of work with a new context that has a user-defined active span.

Operation Names

The default operation name for any span is the RPC method name (Grpc.Core.Method<TRequest, TResponse>.FullName). However, you may want to add your own prefixes, alter the name, or define a new name. For examples of good operation names, check out the OpenTracing semantics.

To alter the operation name, you need to add an implementation of the interface IOperationNameConstructor to the ClientTracingInterceptor.Builder or ServerTracingInterceptor.Builder. For example, if you want to add a prefix to the default operation name of your ClientInterceptor, your code would look like this:

public class CustomPrefixOperationNameConstructor : IOperationNameConstructor
{
    public string ConstructOperationName<TRequest, TResponse>(Method<TRequest, TResponse> method)
    {
        return "your-prefix" + method.FullName;
    }
    public string ConstructOperationName(string method)
    {
        return "your-prefix" + method;
    }
}

ClientTracingInterceptor interceptor = ClientTracingInterceptor.Builder ...
    .WithOperationName(new CustomPrefixOperationNameConstructor())
    .With....
    .Build()

You can also use the default implementation using PrefixOperationNameConstructor:

ClientTracingInterceptor interceptor = ClientTracingInterceptor.Builder ...
    .WithOperationName(new PrefixOperationNameConstructor("your-prefix"))
    .With....
    .Build()

Due to how the C# version of GRPC interceptors are written, it's currently not possible get more information on the method than the method name in an ServerTracingInterceptor.

Integrating with Other Interceptors

GRPC provides Intercept(Interceptor) methods that allow you chaining multiple interceptors. Preferably put the tracing interceptor at the top of the interceptor stack so that it traces the entire request lifecycle, including other interceptors:

Server

Server server = new Server
{
    Services = { SomeService.BindService(new SomeServiceImpl()).Intercept(someInterceptor).Intercept(someOtherInterceptor).Intercept(serverTracingInterceptor) }
    Ports = ...
};

Client

client = new SomeService.SomeServiceClient(this.channel.Intercept(someInterceptor).Intercept(someOtherInterceptor).Intercept(clientTracingInterceptor));