Clustering EMQ X Automatically:static, using a static node list

The simplest way to automatically create EMQ X Broker cluster is to use configure list of static nodes on each member node of EMQ X Broker cluster.

Let’s start with creating cluster of 3 EMQ X Broker nodes.

1. Setup EMQ X Broker Nodes

Follow the guidelines presented in my previous article Setup EMQ X broker node on Ubuntu Server to setup 3 EMQ X nodes. So we have 3 EMQ X nodes setup as following.

You can set node name of EMQ X Broker Node using the node.name property defined in /etc/emqx/emqx.conf configuration file. Following are detailed steps to set the node name of EMQ X Broker Node, follow these steps to setup node.name property on each member node.

Set EMQ X Cluster Cookie

All nodes in EMQ X Cluster need to have same cookie value, this helps EMQ X to recognize nodes of the same EMQ X Cluster. You can set cookie value of EMQ X Broker Node using node.cookie property in /etc/emqx/emqx.confconfiguration file.

Configuring the EMQ X Cluster Mode

We can set the cluster mode for EMQ X Cluster using cluster.discoveryproperty in /etc/emqx/emqx.conf configuration file.

1. Open the /etc/emqx/emqx.conf configuration file.sudo nano /etc/emqx/emqx.conf
2. Search for cluster.discovery property.## Value: Enum ## - manual: Manual join command ## - static: Static node list ## - mcast: IP Multicast ## - dns: DNS A Record ## - etcd: etcd ## - k8s: Kubernates ## ## Default: manual cluster.discovery = manual
3. Set static as value of cluster.discovery property.cluster.discovery = static Please note that default value for cluster.discovery property is manual, you need to change value of cluster.discovery property to static for each member node of EMQ X Cluster.

Configure EMQ X Cluster Nodes

To setup EMQ X Cluster with static mode you need to set node names of all member nodes against cluster.static.seeds property in /etc/emqx/emqx.conf configuration file of each member node.

Following are the steps to configure each member node to create EMQ X Clusterwith static mode.

1. Open /etc/emqx/emqx.conf (EMQ X configuration) file for editing.sudo nano /etc/emqx/emqx.conf
2. Search for cluster.static.seeds property.

## Cluster using static node list

## Node list of the cluster.
##
## Value: String
## cluster.static.seeds = emqx1@127.0.0.1,emqx2@127.0.0.1

1. Set comma separated list of node names of all member nodes.cluster.static.seeds = emqx@192.168.0.31,emqx@192.168.0.32,emqx@192.168.0.33

Repeat step 1 to step 3 for all member nodes of EMQ X Cluster.

Checking Status of EMQ X Cluster

We can use emqx_ctl cluster status command to check status of EMQ X Cluster. Run emqx_ctl cluster status command on any member node of EMQ X Cluster as following.

emqx_ctl cluster status

Output

Cluster status: [{running_nodes,['emqx@192.168.0.31','emqx@192.168.0.32',
                                 'emqx@192.168.0.33']}]

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!

Other articles in MQTT / EMQ X series

• Setup EMQ X broker node on Ubuntu Server
• Understanding EMQ X broker cluster concepts
• How to manually setup EMQ X cluster?
• Load Balancer for EMQ X Cluster
• EMQ X deployment with HAProxy Load Balancer on private network