Listen

Binds and listens for connections on the specified address. This can be a int for port or string for address.

app.Listen(address interface{}, tls ...*tls.Config) error

app.Listen(8080)
app.Listen("8080")
app.Listen(":8080")
app.Listen("127.0.0.1:8080")

To enable TLS/HTTPS you can append a TLS config.

cer, err := tls.LoadX509KeyPair("server.crt", "server.key")
if err != nil {
    log.Fatal(err)
}
config := &tls.Config{Certificates: []tls.Certificate{cer}}
 
app.Listen(443, config)