Chi

Use the Last9 Go Agent to instrument your Chi v5 application with automatic tracing and metrics. The agent wraps the official OpenTelemetry Chi middleware — full OTel compliance with minimal code changes.

Prerequisites

• Go 1.22 or higher
• Chi v5 (github.com/go-chi/chi/v5)
• Last9 account with OTLP credentials

Installation

1. Install the Last9 Go Agent

   go get github.com/last9/go-agent

2. Set Environment Variables

   export OTEL_SERVICE_NAME="your-chi-service"
   export OTEL_EXPORTER_OTLP_ENDPOINT="$last9_otlp_endpoint"
   export OTEL_EXPORTER_OTLP_HEADERS="Authorization=$last9_otlp_auth_header"
   export OTEL_TRACES_SAMPLER="always_on"
   export OTEL_RESOURCE_ATTRIBUTES="deployment.environment=production"

3. Instrument your application

   • New application
   • Existing application

   Replace chi.NewRouter() with chiagent.New() — that’s the only change required:

   package main
   
   import (
       "log"
       "net/http"
   
       "github.com/last9/go-agent"
       chiagent "github.com/last9/go-agent/instrumentation/chi"
   )
   
   func main() {
       if err := agent.Start(); err != nil {
           log.Fatalf("failed to start agent: %v", err)
       }
       defer agent.Shutdown()
   
       // Drop-in replacement for chi.NewRouter()
       r := chiagent.New()
   
       r.Get("/", indexHandler)
       r.Get("/users/{id}", getUserHandler)
       r.Post("/users", createUserHandler)
   
       log.Fatal(http.ListenAndServe(":8080", r))
   }

Database Instrumentation

Use the agent’s database integration for automatic SQL query tracing. Supported drivers: PostgreSQL, MySQL, SQLite.

import "github.com/last9/go-agent/integrations/database"

db, err := database.Open(database.Config{
    DriverName:   "postgres",
    DSN:          "postgres://user:pass@localhost/mydb",
    DatabaseName: "mydb",
})
if err != nil {
    log.Fatal(err)
}
defer db.Close()

// Use db normally — all queries are automatically traced
func getUserHandler(w http.ResponseWriter, r *http.Request) {
    id := chi.URLParam(r, "id")
    rows, err := db.QueryContext(r.Context(), "SELECT id, name FROM users WHERE id = $1", id)
    // ...
}

The agent automatically extracts server.address, server.port, db.user, and db.name from the DSN and attaches them to every span.

Redis Instrumentation

import redisagent "github.com/last9/go-agent/integrations/redis"

// Drop-in replacement for redis.NewClient()
rdb := redisagent.NewClient(&redis.Options{
    Addr: "localhost:6379",
})

func cacheHandler(w http.ResponseWriter, r *http.Request) {
    val, err := rdb.Get(r.Context(), "key").Result()
    // ...
}

HTTP Client Instrumentation

For outgoing requests with automatic traceparent propagation:

import httpagent "github.com/last9/go-agent/integrations/http"

client := httpagent.NewClient(&http.Client{
    Timeout: 10 * time.Second,
})

func proxyHandler(w http.ResponseWriter, r *http.Request) {
    req, _ := http.NewRequestWithContext(r.Context(), "GET", "https://upstream.example.com/api", nil)
    resp, err := client.Do(req)
    // ...
}

What Gets Traced Automatically

View Traces and Metrics

After running your application, navigate to Trace Explorer and Metrics Explorer in Last9 to view your telemetry data.

Troubleshooting

Please get in touch with us on Discord or Email if you have any questions.