Table of contents

1. Overview
2. Response Time Logging
   1. Filtering response time logs
3. Adding interceptors to your gRPC server
4. Adding interceptors to your gRPC client
5. Adding custom interceptors to Default interceptors

Overview

When you create a new service with ColdBrew cookiecutter it will automatically add tracing (New Relic / Opentelemetry) to your gRPC services. This is done by adding the interceptors to your gRPC server.

To disable coldbrew provided interceptors you can call the function UseColdBrewServcerInterceptors.

Response Time Logging

Coldbrew uses interceptors to implement response time logging in ResponseTimeLoggingInterceptor. The interceptor is enabled by default and logs the response time of each request in the following format:

{"@timestamp":"2023-04-23T22:07:38.857192+08:00","caller":"interceptors@v0.1.7/interceptors.go:248","error":null,"grpcMethod":"/com.github.ankurs.MySvc/Echo","level":"info","took":"49.542µs","trace":"50337410-4bcd-48ce-b8d4-6b42f2ac5503"}

Filtering response time logs

Its possible to filter out response time logs message by using a FilterFunc, Coldbrew provides a default filter function implementation that filter out common logs like healthchek, readycheck, server reflection, etc.

You can add more methods to filter out by appending to the default FilterMethods list. For example, to filter out all methods that starts with com.github.ankurs.MySvc/:

import (
    "github.com/go-coldbrew/interceptors"
)

func main() {
    interceptors.FilterMethods = append(interceptors.FilterMethods, "com.github.ankurs.MySvc/")
}

You can also provide your own filter function by calling the SetFilterFunc variable:

import (
    "github.com/go-coldbrew/interceptors"
)

func main() {
    interceptors.SetFilterFunc(context.Background(), func(ctx context.Context, method string) bool {
        return strings.HasPrefix(method, "com.github.ankurs.MySvc/")
    })
}

Adding interceptors to your gRPC server

If you want to add interceptors to your gRPC server, you can use the Default Interceptors from interceptors package to add the ColdBrew interceptors to your gRPC server.

Example:

import (
    "context"
    "github.com/go-coldbrew/interceptors"
    "github.com/go-coldbrew/log"
    "google.golang.org/grpc"
)

func main() {
    server := grpc.NewServer(
        // Add the ColdBrew interceptors to your gRPC server to add tracing/metrics to your gRPC server calls
        grpc.ChainUnaryInterceptor(interceptors.DefaultInterceptors()...),
    )
    pb.RegisterHelloWorldServer(server, &HelloWorldServer{})
    if err := server.Serve(lis); err != nil {
        log.Fatal(context.Background(), err)
    }
}

If you are using ColdBrew cookiecutter, the interceptors will be added automatically to your gRPC server.

Adding interceptors to your gRPC client

ColdBrew provides gRPC client interceptors to add tracing/metrics to your gRPC client. You can add Default Client Interceptors which are a collection of interceptors provided by ColdBrew, or you can add your own interceptors.

Example:

import (
    "github.com/go-coldbrew/interceptors"
    "github.com/go-coldbrew/log"
    "google.golang.org/grpc"
)

func main() {
    ctx := context.Background()
    conn, err := grpc.Dial(
        "localhost:8080",
        grpc.WithInsecure(),
        // Add the ColdBrew interceptors to your gRPC client to add tracing/metrics to your gRPC client calls
        grpc.WithChainUnaryInterceptor(interceptors.DefaultClientInterceptors()...),
    )
    if err != nil {
        log.Fatal(ctx, err)
    }
    defer conn.Close()
    client := pb.NewHelloWorldClient(conn)
    resp, err := client.HelloWorld(ctx, &pb.HelloWorldRequest{})
    if err != nil {
        log.Fatal(ctx, err)
    }
    log.Info(ctx, resp)
}

Adding custom interceptors to Default interceptors

You can add your own interceptors to the Default Interceptors by appending to the list of interceptors.

Use the function AddUnaryServerInterceptor and AddUnaryClientInterceptor to add your own interceptors to the default server and client interceptors.