Go📦Standard Libraryintermediate
net/http — HTTP Client and Server
Go · Standard Library · Run with go run
Explanation
`net/http` is a production-grade HTTP/1.1 and HTTP/2 library in the standard library. `http.ListenAndServe` starts a server; `http.HandleFunc` registers routes. The `http.Client` makes HTTP requests with full control over timeouts, redirects, and TLS. Always set timeouts on production clients — the zero-value `http.DefaultClient` has no timeouts.
Real-World Scenario
Microservices written in Go use `net/http` directly (no framework) for simple APIs. A service adds authentication middleware by wrapping `http.Handler` — the composition pattern means no magic, just function calls.
Quick Snippet
snippet.go
// Server
http.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusOK)
fmt.Fprintln(w, `{"status":"ok"}`)
})
log.Fatal(http.ListenAndServe(":8080", nil))
// Client with timeout (always set in production)
client := &http.Client{Timeout: 10 * time.Second}
resp, err := client.Get("https://api.example.com/users")
if err != nil { return err }
defer resp.Body.Close()
body, _ := io.ReadAll(resp.Body)Full Example
http_server.go
// Compile: go run http_server.go
// Then: curl http://localhost:8080/health
// Output: {"status":"ok"}
package main
import (
"encoding/json"
"fmt"
"log"
"net/http"
"time"
)
type HealthResponse struct {
Status string `json:"status"`
Timestamp time.Time `json:"timestamp"`
}
func healthHandler(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(HealthResponse{
Status: "ok",
Timestamp: time.Now(),
})
}
func helloHandler(w http.ResponseWriter, r *http.Request) {
name := r.URL.Query().Get("name")
if name == "" {
name = "World"
}
fmt.Fprintf(w, "Hello, %s!\n", name)
}
func main() {
mux := http.NewServeMux()
mux.HandleFunc("/health", healthHandler)
mux.HandleFunc("/hello", helloHandler)
server := &http.Server{
Addr: ":8080",
Handler: mux,
ReadTimeout: 5 * time.Second,
WriteTimeout: 10 * time.Second,
}
log.Println("listening on :8080")
log.Fatal(server.ListenAndServe())
}
Run command
go run http_server.go