init push

cmd/healthcheck/main.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"bufio"
+	"net"
+	"os"
+	"strings"
+	"time"
+)
+
+const (
+	defaultTarget = "http://127.0.0.1:8080/health"
+	timeout       = 2 * time.Second
+)
+
+func main() {
+	target := strings.TrimSpace(os.Getenv("HEALTHCHECK_URL"))
+	if target == "" {
+		target = defaultTarget
+	}
+	if len(os.Args) > 1 {
+		if arg := strings.TrimSpace(os.Args[1]); arg != "" {
+			target = arg
+		}
+	}
+
+	addr, path, ok := splitTarget(target)
+	if !ok {
+		os.Exit(1)
+	}
+
+	conn, err := net.DialTimeout("tcp", addr, timeout)
+	if err != nil {
+		os.Exit(1)
+	}
+	defer conn.Close()
+
+	_ = conn.SetDeadline(time.Now().Add(timeout))
+	request := "GET " + path + " HTTP/1.1\r\nHost: " + addr + "\r\nConnection: close\r\n\r\n"
+	if _, err := conn.Write([]byte(request)); err != nil {
+		os.Exit(1)
+	}
+
+	line, err := bufio.NewReader(conn).ReadString('\n')
+	if err != nil {
+		os.Exit(1)
+	}
+
+	fields := strings.Fields(line)
+	if len(fields) < 2 {
+		os.Exit(1)
+	}
+
+	code := fields[1]
+	if len(code) != 3 || (code[0] != '2' && code[0] != '3') {
+		os.Exit(1)
+	}
+}
+
+func splitTarget(target string) (string, string, bool) {
+	target = strings.TrimSpace(target)
+	if target == "" || strings.HasPrefix(target, "https://") {
+		return "", "", false
+	}
+
+	target = strings.TrimPrefix(target, "http://")
+	addr := target
+	path := "/"
+	if slash := strings.IndexByte(target, '/'); slash >= 0 {
+		addr = target[:slash]
+		path = target[slash:]
+	}
+
+	if addr == "" || !strings.Contains(addr, ":") {
+		return "", "", false
+	}
+
+	return addr, path, true
+}