How to use consul key/value pair in configuration file?

consul
By Vikrant
September 9, 2018

Consul key/value pair feature is similar to what we have in zookeeper or etcd. This article is in continution from the previous one.

  • I have created the following key/pairs using the consul UI.
/ # consul kv export --http-addr=192.168.99.101:8500 testbed/
[
  {
    "key": "testbed/",
    "flags": 0,
    "value": ""
  },
  {
    "key": "testbed/haproxy/",
    "flags": 0,
    "value": ""
  },
  {
    "key": "testbed/haproxy/maxconn",
    "flags": 0,
    "value": "MTA5Ng=="
  },
  {
    "key": "testbed/haproxy/stats",
    "flags": 0,
    "value": "ZGlzYWJsZQ=="
  },
  {
    "key": "testbed/haproxy/timeout connect",
    "flags": 0,
    "value": "MTBz"
  }
]
  • In the running container made the following change in haproxy.cfg file. I have just changed the value of stats to make it configurable through key/value pairs.
root@eded5099ee05:/# cat /etc/haproxy/haproxy.tmpl
global
  maxconn 4096
defaults
  mode http
  timeout connect 5s
  timeout client 50s
  timeout server 50s
listen http-in
  bind *:80
  server  :

  stats 
  stats uri /haproxy
  stats refresh 5s

  • After making above change logout from docker and do the docker stop/start to bring that change into effect.

  • Issue the following command to see the live action, change the stats parameter either using API or consul UI and you will see the value of stats changed accrodingly instantaneously.

root@eded5099ee05:/# /usr/local/bin/consul-template -consul=192.168.99.101:8500 -config=/lb-consul-template.hcl --dry
> /etc/haproxy/haproxy.cfg
global
  maxconn 4096
defaults
  mode http
  timeout connect 5s
  timeout client 50s
  timeout server 50s
listen http-in
  bind *:80
  server consulclient1 192.168.99.102:8080
  server consulclient2 192.168.99.103:8080

  stats enable
  stats uri /haproxy
  stats refresh 5s



> /etc/haproxy/haproxy.cfg
global
  maxconn 4096
defaults
  mode http
  timeout connect 5s
  timeout client 50s
  timeout server 50s
listen http-in
  bind *:80
  server consulclient1 192.168.99.102:8080
  server consulclient2 192.168.99.103:8080

  stats disable
  stats uri /haproxy
  stats refresh 5s