Backends "use-server" with dynamic name

[vladoportos]

Hello all,

I’m trying to create redirect if java console redirect to my proxy url /redirect/something?host=host1
then it gets basically redirected to that host in url parameter. The problem is the backend server list is not static at all, new servers are added and removed all the time…

I would need something like this to work:

frontend customer_facing
  mode http
  bind <ip>:80
  bind <ip>:443 ssl crt /etc/ssl/private/key.pem
  http-request redirect scheme https unless { ssl_fc }
  use_backend console_redirect if { path_beg /redirect }

backend console_redirect
  mode http
  use-server urlp(host) if { urlp(host) -m found }  <-- this does not work 
  server test 127.0.0.1:80

I think I can use dataplane API to insert new server test2, server test3 etc into the config without reloading the whole haproxy… but I need the backend to choose correct server base on the host variable from URL…

So If i do https:///redirect/something?host=test it gets redirected to the server called “test” in the backend

I really need some help with this

[vladoportos]

Funny enough, this seems to work:

use-server %[urlp(host)] if { urlp(host) -m found }

But if I have more servers in the backend, then if he does not find the server specified in use-server it chooses round-robin any of the servers in there… I need it to either choose a specific server defined by use-server or not use any of them… fail or go to some default

[vladoportos]

Ok so I went one level up and add choosing between whole backends with:

`use_backend %[urlp(host)] if { urlp(host) -m found }

and then having just one server in backend… this is kind of working but its adding additional API calls to whole system, now I will have to create backend, then add server to it… there must be a simpler solution.

[Toni]

Hi
I just noticed, there was a similar thread already:

Dynamic backend switching using nbsrv with Host header

Hi I am using haproxy 2.4.7, and I would like to dynamically route to the correct backend, if the backend has available servers. I struggle to find the correct syntax using nbsrv(). The error I am getting is: # haproxy -c -f /etc/haproxy/haproxy.cfg [NOTICE] (31364) : haproxy version is 2.4.7-b5e51a5 [NOTICE] (31364) : path to executable is /sbin/haproxy [ALERT] (31364) : parsing [/etc/haproxy/haproxy.cfg:18] : error detected while parsing switching rule : missing comma after fetch ke…

Toni

[Rickard_505]

Hi, iam trying to get this to work, but it seems you can not use ssl_fc_sni this way…?

use_backend bk_%[ssl_fc_sni,lower]

funny thing this works in same frontend.
ACL
demo ssl_fc_sni -i demo.abc.xyz
Action
backend bk_demo.abc.xyz if demo

tried direct mapping and with map-file same result .