# Configure Load Balancer

Load Balancer (LB) balances the load among multiple network components and optimizes resource usage to avoid system malfunctions caused by overload. LB is not a mandatory component in EMQX, but it can bring some obvious system benefits, for example:

  • Balance the load of EMQX to avoid single node overload;
  • Simplify client configuration, the client only needs to connect to the LB and need not worry about the scaling within the cluster;
  • Reduce the load of EMQX clusters by TLS/SSL termination;
  • Improve cluster security, with LB configured at the front end of the cluster, unwanted traffic can be blocked to protect the EMQX cluster from malicious attacks.

This chapter introduces how to configure LB in EMQX.

# Architecture

For an EMQX cluster configured with LB, the LB handles the incoming TCP traffic and then distributes the received MQTT connection requests and messages to different EMQX nodes. The typical deployment architecture is as follows:

# Deployment Architecture

EMQX cluster can be deployed as an IoT access service (IoT Hub). Currently, EMQ provides free software images out of the box on cloud service providers such as QingCloud, Aliyun, and AWS. For special hardware platforms and system versions such as Raspberry Pi and Linux ARM, source code compilation and installation can be used.

TLS termination

If SSL/TLS is enabled, it is recommended to terminate the SSL/TLS connection at LB, that is, to use SSL/TLS to secure the connection between clients and LB and then use TCP connection between LB and EMQX nodes, maximizing the performance of the EMQX cluster. The architecture is as follows:



You can also use DNS polling for load balancing for test or development purposes.

# Select an LB Product

Many load-balancing products are currently available, including open-source and commercial editions, and public cloud providers also have their load-balancing services.

LB products for public cloud:

Cloud providerSSL TerminationLB Product
AWS (opens new window)Yeshttps://aws.amazon.com/elasticloadbalancing/?nc1=h_ls (opens new window)
Azure (opens new window)Unknownhttps://azure.microsoft.com/en-us/products/load-balancer/ (opens new window)
Google Cloud (opens new window)Yeshttps://cloud.google.com/load-balancing (opens new window)

LB products for private cloud:

Open-Source LBSSL TerminationDOC/URL
HAProxy (opens new window)Yeshttps://www.haproxy.com/solutions/load-balancing.html (opens new window)
NGINX (opens new window)Yeshttps://www.nginx.com/solutions/load-balancing/ (opens new window)

The following section takes the HAProxy or NGINX as an example to illustrate how to configure an LB in EMQX cluster.

# Configure HAProxy/NGINX in EMQX

Suppose you have a cluster with 2 EMQX nodes, with emqx1 on and emqx2 on, you can follow the steps below to add HAProxy or NGINX as the LB.

# Enable Proxy Protocol

To configure the HAProxy or Nginx on port 1883, you first need to enable the configuration item proxy_protocol in etc/listeners.conf by setting it to on

Code Example:

listener.tcp.external.proxy_protocol = on


For proxy protocols and that used in Nginx, see:

# Configure HAProxy/NGINX