I have been in DevOps related jobs for past 6 years dealing mainly with Kubernetes in AWS and on-premise as well. I spent quite a lot …
Go simple TCP hands on
package main
import (
"bufio"
"fmt"
"log"
"net"
"time"
"strings"
)
func main() {
li, err := net.Listen("tcp", ":8080")
if err != nil {
log.Fatalln(err)
}
defer li.Close()
for {
conn, err := li.Accept()
if err != nil {
log.Fatalln(err)
}
go serve(conn)
}
}
func serve(conn net.Conn) {
err := conn.SetDeadline(time.Now().Add(30 * time.Second))
if err != nil {
log.Println(err)
}
scanner := bufio.NewScanner(conn)
del := `[---------------]`
fmt.Printf("Received: %v\n\n", del)
i := 0
// the following loop works in a way:
// 1. run: curl -H "X-Head:Jao" -X POST http://127.0.0.1:8080/aaa
// 2. curl sends:
// index: [0]: POST /aaaaaaaa HTTP/1.1
// index: [1]: Host: 127.0.0.1:8080
// index: [2]: User-Agent: curl/7.72.0
// index: [3]: Accept: */*
// index: [4]: X-Content-type:Jano
// index: [5]:
// 3. scanner.Scan() scans this 6 lines
// 4. and prints them: periodically
// 5. after an empty line => we write body variable :)
var method string
var path string
for scanner.Scan() {
ln := scanner.Text()
// what I received as a server from a client
fmt.Printf("[%v]: %v\n", i, ln)
// how I am going to respond to client
// io.WriteString(conn, "I the server say: Hello!\n - " + ln)
// fmt.Printf("\n\n%v\n\n", del)
if i == 0 {
splitOnSpace := strings.Fields(ln)
method = splitOnSpace[0]
path = splitOnSpace[1]
}
if ln == "" {
fmt.Println("THIS IS THE END :)")
break
}
i++
}
body := response(method, path)
fmt.Fprintf(conn, "HTTP/1.1 200 OK\r\n")
fmt.Fprintf(conn, "Content-Type: text/html\r\n")
fmt.Fprintf(conn, "Content-Length: %d\r\n", len(body))
fmt.Fprintf(conn, "\r\n")
fmt.Fprintf(conn, body)
fmt.Printf("END: %v\n\n", del)
defer conn.Close()
// io.WriteString(conn, "I can see you connected")
}
func response(m string, url string) string {
body := `
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Input Type Submit</title>
</head>
<body>
<h1>Hello from GO!
` + "Method: " + m + " Requested URL: " + url + `
</h1>
</body>
</html>
`
return body
}