Is it possible to choose traffic path based on whatever is available at the moment, with priority?

Hello guys

I have a frontend and backend that looks like this:

frontend httpPort
    mode http
    bind 0.0.0.0:80

    default_backend httpPortTcpForwarder

backend httpPortTcpForwarder
    mode http
    server first_to_try  127.0.0.1:5588 
    server second_to_try 10.0.0.2:5588 
    server last_to_try 127.0.0.1:8080

For my application, first_to_try and second_to_try are most of the time closed (layer 4, connection refused), but open in certain occasions. I’d like to have haproxy attempt to communicate with first_to_try, if it gets “connection refused”, then move to the second option and try it. If it gets “connection refused” again, to move to the default_backend. Is that possible to achieve?

And if you’re wondering why… let’s just call it a blessing of letsencrypt.

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