HAProxy(High Availibility Proxy) is an open source TCP / HTTP proxy solution to create highly available systems. HAProxy is widely used open source load balancer. In this article we will learn how to use HAProxy as load balancer for EMQX Cluster.
To get yourself familiar with basic concepts of HAProxy and it’s installation process please refer to following articles.
- Understanding Core Concepts of HAProxy as Load Balancer Solution.
- How To Install HAProxy on Ubuntu Linux Server.
In my previous article Clustering EMQ X Automatically:static, using a static node list, I explained how to setup cluster of three EMQX broker nodes using static node list. In this article we will add load balancing capability to this cluster using HAProxy.
Let’s get started.
Configure HAProxy Backend for EMQX nodesand EMQX Dashboard
We will configure EMQX nodes as backend of HAProxy, this means requestsreceived by HAProxy will be forwarded to EMQX nodes defined as backend.
Go to the system with HAProxy installed and open HAProxy configuration file as following.
sudo nano /etc/haproxy/haproxy.cfg
This will load the haproxy.cfg configuration file with default contents, go to the end of haproxy.cfg file and define backend for EMQX nodes as following.
backend backend_emqx_tcp
balance roundrobin
server emqx_node_1 192.168.0.31:1883 check
server emqx_node_2 192.168.0.32:1883 check
server emqx_node_3 192.168.0.33:1883 check
Next we will define backend for EMQX Dashboard access.
backend backend_emqx_dashboard
balance roundrobin
server emqx_node_1 192.168.0.31:18083 check
server emqx_node_2 192.168.0.32:18083 check
server emqx_node_3 192.168.0.33:18083 check
Configure HAProxy Frontend for EMQX nodesand EMQX Dashboard
Now we will define HAProxy frontends to forward incoming requests for EMQX node and EMQX Dashboard to respective backend defined in previous section.
Open HAProxy configuration file (/etc/haproxy/haproxy.cfg) in your favorite text editor, move to the end of file and add configurations for EMQX nodes frontend as following.
frontend frontend_emqx_tcp
bind *:1883
option tcplog
mode tcp
default_backend backend_emqx_tcp
Next define the frontend configuration for EMQX Dashboard.
frontend frontend_emqx_dashboard
bind *:18083
option tcplog
mode tcp
default_backend backend_emqx_dashboard
Restart HAProxy service and Check Status of EMQX Backend and Frontend
Restart the haproxy service to reload the configurations changes we made in previous section.
sudo service haproxy restart
Check current status of haproxy service.
sudo service haproxy status
This will print current status of haproxy service.
● haproxy.service - HAProxy Load Balancer
Loaded: loaded (/lib/systemd/system/haproxy.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2019-03-25 21:40:37 PKT; 3h 8min ago
Docs: man:haproxy(1)
file:/usr/share/doc/haproxy/configuration.txt.gz
Process: 12748 ExecStartPre=/usr/sbin/haproxy -f ${CONFIG} -c -q (code=exited, status=0/SUCCESS)
Main PID: 12753 (haproxy-systemd)
Tasks: 3
Memory: 1.0M
CPU: 321ms
CGroup: /system.slice/haproxy.service
├─12753 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid
├─12754 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
└─12758 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
Mar 25 21:40:37 u-srv-1 systemd[1]: Starting HAProxy Load Balancer...
Mar 25 21:40:37 u-srv-1 systemd[1]: Started HAProxy Load Balancer.
Mar 25 21:40:37 u-srv-1 haproxy-systemd-wrapper[12753]: haproxy-systemd-wrapper: executing /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
u1@u-srv-1:~$ sudo service haproxy restart
u1@u-srv-1:~$ sudo service haproxy status
● haproxy.service - HAProxy Load Balancer
Loaded: loaded (/lib/systemd/system/haproxy.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-03-26 00:49:33 PKT; 2s ago
Docs: man:haproxy(1)
file:/usr/share/doc/haproxy/configuration.txt.gz
Process: 12858 ExecStartPre=/usr/sbin/haproxy -f ${CONFIG} -c -q (code=exited, status=0/SUCCESS)
Main PID: 12863 (haproxy-systemd)
Tasks: 3
Memory: 1.5M
CPU: 18ms
CGroup: /system.slice/haproxy.service
├─12863 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid
├─12865 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
└─12868 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
Mar 26 00:49:33 u-srv-1 systemd[1]: Started HAProxy Load Balancer.
Mar 26 00:49:33 u-srv-1 haproxy-systemd-wrapper[12863]: haproxy-systemd-wrapper: executing /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy backend_emqx_tcp started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy backend_emqx_tcp started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy backend_emqx_dashboard started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy backend_emqx_dashboard started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy frontend_emqx_tcp started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy frontend_emqx_tcp started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy frontend_emqx_dashboard started.
Mar 26 00:49:33 u-srv-1 haproxy[12865]: Proxy frontend_emqx_dashboard started.
The last 8 lines of output of haproxy service status confirms the successful start of our backend and frontend services.
Test the EMQX Cluster with HAProxy Load Balancer
Let’s connect to EMQX Dashboard using the IP or Hostname of HAProxy.
Launch a web browser visit http://HAPROXY_HOSTNAME_OR_IP:18083, or use mosquitto mqtt client to connect to EMQX Cluster using HAProxy node.
mosquitto_pub -h HAPROXY_HOSTNAME_OR_IP -p 1883 -t myTopic -m HelloMQTT
Note: Replace HAPROXY_HOSTNAME_OR_IP with valid host name or ip addressassigned to system with HAProxy.
That’s it, hope you enjoyed it. You like this article, have any questions or suggestions please let us know in the comments section.
Thanks and Happy Learning!
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