go-services

Go HTTP Services AI Skill Guide

Overview & Engine Architecture

Go services are typically single static binaries with net/http (or a thin router), goroutines for concurrency, and context.Context for deadlines and cancellation. Agents keep packages small, return errors explicitly (no panic for control flow), propagate context into DB/HTTP clients, and use go test table-driven tests as the default quality gate.

main -> http.Server
          |
     mux / chi / echo
          |
   handlers -> services -> stores
          |
     context cancel / timeout

When to use this skill

• Building REST/JSON backends in Go
• Structuring modules (go.mod) and internal packages
• Fixing leaked goroutines or ignored contexts
• Hardening graceful shutdown

Operational directives

1. Accept context.Context as the first parameter on I/O methods.
2. Wrap errors with %w and handle at the edge with stable HTTP status mapping.
3. Prefer stdlib net/http + small router unless the team already standardized.
4. Run go vet and race detector on critical packages (go test -race).
5. Set read/write/idle timeouts on http.Server - never listen with zero timeouts in prod.

Handler sketch

package main

import (
  "encoding/json"
  "net/http"
  "time"
)

type ItemIn struct {
  SKU string `json:"sku"`
  Qty int    `json:"qty"`
}

func createItem(w http.ResponseWriter, r *http.Request) {
  var in ItemIn
  if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<20)).Decode(&in); err != nil {
    http.Error(w, "bad json", http.StatusBadRequest)
    return
  }
  if in.SKU == "" || in.Qty < 0 {
    http.Error(w, "invalid item", http.StatusBadRequest)
    return
  }
  w.Header().Set("content-type", "application/json")
  w.WriteHeader(http.StatusCreated)
  _ = json.NewEncoder(w).Encode(map[string]any{"id": 1, "sku": in.SKU, "qty": in.Qty})
}

func main() {
  mux := http.NewServeMux()
  mux.HandleFunc("POST /items", createItem)
  srv := &http.Server{
    Addr:              ":8080",
    Handler:           mux,
    ReadHeaderTimeout: 5 * time.Second,
  }
  _ = srv.ListenAndServe()
}