pausing traffic and retries with Caddy

You can pause incoming reqs, when your backend is down with Caddy’s lb_try_duration
and do retries with interval with lb_try_interval policy.

Ref : https://til.simonwillison.net/caddy/pause-retry-traffic

If you want Caddy to forward the request to the next server available then you can specify a list of available upstreams/servers beforehand in the Caddyfile with lb_policy set to first. Something like this :

Caddyfile

{
    auto_https off
}
:80 {
    reverse_proxy localhost:8003 localhost:8084 localhost:8085 {
        lb_policy first
        lb_try_duration 30s
        lb_try_interval 1s
    }
}

Caddy will basically forward the request to the next available server if available and so on..

Checkout more load balancing options here

You can also swap in a new backend with dynamic upstreams, to which Caddy will route held up as well as the new incoming requests.

More discussed in this github issue