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Accepted
Wayne Werner
Asked: 2014-12-23 13:02:08 +0800 CST

How do I inform HAProxy that my server is back up?

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I'm a bit of a HAProxy newbie - I've got 3 docker containers, one running HAProxy with the following config:

global                                                                             
  log 127.0.0.1 local0                                                             
  log 127.0.0.1 local1 notice                                                      
  chroot /var/lib/haproxy                                                          
  user haproxy                                                                     
  group haproxy                                                                    
  stats socket /var/run/haproxy.sock mode 600 level admin                          
  # daemon                                                                         

defaults                                                                           
  log global                                                                       
  mode http                                                                        
  option httplog                                                                   
  option dontlognull                                                               
  timeout connect 5000ms                                                           
  timeout client 50000ms                                                           
  timeout server 50000ms                                                           
  balance source                                                                   

listen stats :80                                                                   
  stats enable                                                                     
  stats uri /haproxy?stats                                                         
  stats realm Strictly\ Private                                                    
  stats auth test:test1234                                                         
  balance roundrobin                                                               
  #option forwardfor                                                               
  default_backend myserv-legacy                                                    

backend myserv-legacy                                                              
  cookie SERVERID insert indirect preserve                                         
  server myserv-A ${MYSERVA_PORT_8080_TCP_ADDR}:8080 cookie A check               
  server myserv-B ${MYSERVB_PORT_8080_TCP_ADDR}:8080 cookie B check

The other two servers are running a webapp using Tomcat.

I brought my two servers down with sudo docker stop myservA myservB, and though I've started them and can connect to them through their exposed ports, they both show as down in HAProxy with a L4TOUT in 2000ms.

Any clue why they wouldn't be showing up as available?

edit:

If I run

$ sudo docker stop haprox && sudo docker start haprox

(haprox is the name of my HAProxy container) then my servers are available again...

haproxy

1 Answers

  1. Best Answer

    I was just about to ask if the value of the address variables was changing, heh.

    The way I've been seeing this done in dynamic containered environments is to use a service discovery tool like etcd or Consul to help the load balancer find the backends - looks like Consul has a tool specifically for the HAProxy use case.

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