How to change which IP address a go-fiber client is using?

Question

I'm using Fiber as an HTTP client to make some requests to an http server, however I'm being rate limited. On my vm I configured 5 different IP addresses (public/private) and have confirmed that they are indeed connected to the internet.

curl --interface 10.0.0.4 ipinfo.io/json
curl --interface 10.0.0.5 ipinfo.io/json
... curl --interface 10.0.0.8 ipinfo.io/json

each one returns a different public facing ip address.

Now I'm interested in making round-robin requests using these local addresses but I'm not so sure how to go about it.

Is there some sort of property or function I can set/call to change where the outgoing request is coming from?

I've looked around at fasthttp.HostClient which fiber.Agent extends but I didn't see anything useful.

Thanks guys.

Answer 1

a := fiber.AcquireAgent()
req := a.Request()
req.Header.SetMethod(fiber.MethodGet)
req.SetRequestURI(fmt.Sprintf(formatUrl, args...))

if err := a.Parse(); err != nil {
    h.Logger.Error("%v", err)
    return fiber.StatusInternalServerError, nil, []error{err}
}

customDialer := fasthttp.TCPDialer{
    Concurrency: 1000,
    LocalAddr: &net.TCPAddr{
        IP: h.IPPool[atomic.AddUint32(&h.IpIdx, 1)%uint32(len(h.IPPool))],
    },
}

a.HostClient.Dial = func(addr string) (net.Conn, error) {
    return customDialer.Dial(addr)
}

Creating a custom dialer and dial func allows you to change the local address associated with the http request.