allow setting port via flag, add systemd service

canihazip.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+    "flag"
     "fmt"
     "net"
     "net/http"
@@ -13,9 +14,12 @@ func getMyIP(w http.ResponseWriter, r *http.Request) {
 }
 
 func main() {
-    fmt.Println("Server running on 0.0.0.0:5000")
+    port := flag.String("port", "5000", "port to listen on")
+    flag.Parse()
+
+    fmt.Printf("== Server running on 0.0.0.0:%s ==\n", *port)
     http.HandleFunc("/", getMyIP)
-    if err := http.ListenAndServe("0.0.0.0:5000", nil); err != nil {
+    if err := http.ListenAndServe("0.0.0.0:"+*port, nil); err != nil {
         panic(err)
     }
 }

canihazip.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=canihazip
+After=network.target
+
+[Service]
+SyslogIdentifier=canihazip
+User=example
+Group=nogroup
+ExecStart=/srv/canihazip/canihazip
+Restart=always
+
+[Install]
+WantedBy=multi-user.target