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Zinc

Add Zinc to an Existing net/http Service

Zinc is an http.Handler, so adopting it does not require a flag day. Keep an existing http.ServeMux, mount it under Zinc, then add Zinc routes where they make the application clearer.

Setup

Section titled “Setup”
Terminal window
mkdir zinc-adoption
cd zinc-adoption
go mod init example.com/zinc-adoption
go get github.com/0mjs/zinc

Application

Section titled “Application”
package main


import (
  "log"
  "net/http"
  "time"


  "github.com/0mjs/zinc"
)


func accessLog(next http.Handler) http.Handler {
  return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    started := time.Now()
    next.ServeHTTP(w, r)
    log.Printf("%s %s %s", r.Method, r.URL.Path, time.Since(started))
  })
}


func main() {
  legacy := http.NewServeMux()
  legacy.HandleFunc("GET /reports", func(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "text/plain; charset=utf-8")
    _, _ = w.Write([]byte("legacy report\n"))
  })


  app := zinc.New()


  // Standard middleware can continue to wrap the whole service.
  app.UseHTTP(accessLog)


  // Mount strips /legacy before the request reaches legacy.
  app.Mount("/legacy", legacy)


  // New endpoints can use Zinc's concise handler API.
  app.Get("/api/health", func(c *zinc.Context) error {
    return c.JSON(zinc.Map{"status": "ok"})
  })


  // Standard handlers can also own individual routed endpoints.
  app.HandleHTTP("GET /metrics", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    _, _ = w.Write([]byte("requests_total 1\n"))
  }))


  log.Fatal(app.Listen(":8080"))
}

Try it

Section titled “Try it”
Terminal window
curl http://localhost:8080/legacy/reports
curl http://localhost:8080/api/health
curl http://localhost:8080/metrics

Choose the smallest integration point

Section titled “Choose the smallest integration point”
  • Use app.Mount("/prefix", handler) when an existing handler owns a subtree.
  • Use app.HandleHTTP("METHOD /path", handler) for one standard handler.
  • Use app.UseHTTP(middleware) for standard middleware around the whole app.
  • Use Zinc handlers for new routes that benefit from context helpers, binding, groups, and framework middleware.

Mounted handlers receive the path with the mount prefix removed. HandleHTTP parameters are available through r.PathValue, just as they are with Go’s standard ServeMux.