Exposing cluster¶

The Operator provides entry points for accessing the database by client applications in several scenarios. In either way the cluster is exposed with regular Kubernetes Service objects, configured by the Operator.

This document describes the usage of Custom Resource manifest options to expose the clusters deployed with the Operator. The expose options vary for different replication types: Asynchronous and Group Replication.

Asynchronous Replication¶

Exposing cluster with HAProxy¶

Percona Operator for MySQL provides load balancing and proxy service with HAProxy (enabled by default).

You can control whether to use it or not by enabling or disabling it via the haproxy.enabled option in the deploy/cr.yaml configuration file.

The following example turns on the asynchronous replication and enables HAProxy:

mysql:
  clusterType: async
  ...
  haproxy: 
   enabled: true
   size: 3
   image: perconalab/percona-xtradb-cluster-operator:0.5.0-haproxy

The resulting HAProxy setup will contain the cluster1-haproxy service listening on ports 3306 (MySQL primary), 3307 (MySQL replicas), and 3309 (the proxy protocol useful for operations such as asynchronous calls).

Note

The Operator currently supports using HAProxy with the asyncrhonous cluster only, and therefore simultaneous enabling of both HAProxy and Group Replication is not possible.

When the cluster is configured in this way, you can find the endpoint (the public IP address of the load balancer in our example) by getting the Service object with the kubectl get service command:

$ kubectl get service cluster1-haproxy
NAME               TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)                      AGE
cluster1-haproxy   ClusterIP   10.76.2.102   <none>        3306/TCP,3307/TCP,3309/TCP   2m32s

Exposing cluster without HAProxy¶

With Asynchronous or Semi-synchronous replication the cluster can be also exposed through a Kubernetes Service called <CLUSTER_NAME>-mysql-primary: for example, cluster1-mysql-primary.

This Service is created by default and is always present. You can change the type of the Service object by setting mysql.primaryServiceType variable in the Custom Resource.

The following example exposes the Primary node of the asynchronous cluster with the LoadBalancer object:

mysql:
  clusterType: async
  ...
  primaryServiceType: LoadBalancer

When the cluster is configured in this way, you can find the endpoint (the public IP address of the load balancer in our example) by getting the Service object with the kubectl get service command:

$ kubectl get service cluster1-mysql-primary
NAME                     TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)                                                         AGE
cluster1-mysql-primary   LoadBalancer   10.40.37.98    35.192.172.85   3306:32146/TCP,33062:31062/TCP,33060:32026/TCP,6033:30521/TCP   3m31s

As you could notice, this command also shows mapped ports the application can use to communicate with MySQL primary instance (e.g. 3306 for the classic MySQL protocol, or 33060 for MySQL X Protocol useful for operations such as asynchronous calls).

Group Replication¶

Clusters configured to use Group Replication are exposed via the MySQL Router through a Kubernetes Service called <CLUSTER_NAME>-router: for example, cluster1-router. Network design in this case looks like this:

MySQL Router can be configured via the router section. In particular, the router.expose.type option sets the type of the correspondent Kubernetes Service object. The following example exposes MySQL Router through a LoadBalancer object:

mysql:
  clusterType: group-replication
  ...
router:
  expose:
    type: LoadBalancer

When the cluster is configured in this way, you can find the endpoint (the public IP address of the load balancer in our example) by getting the Service object with the kubectl get service command:

$ kubectl get service cluster1-router
NAME                TYPE           CLUSTER-IP    EXTERNAL-IP     PORT(S)                                                       AGE
my-cluster-router   LoadBalancer   10.20.22.90   35.223.42.238   6446:30852/TCP,6447:31694/TCP,6448:31515/TCP,6449:31686/TCP   18h

As you could notice, this command also shows mapped ports the application can use to communicate with MySQL Router:

3306 - read/write, default MySQL clients connection,
33062 - read/write, port for MySQL administrative connections,
6446 - read/write, routing traffic to a Primary node,
6447 - read-only, load balancing the traffic across Replicas.

Additionally, ports 6448 and 6449 are available in the same way to connect via MySQL X Protocol useful for operations such as asynchronous calls.

Alternatively, you can find the endpoint to connect to by kubectl get ps command:

$ kubectl get ps
NAME       REPLICATION         ENDPOINT        STATE   AGE
cluster1   group-replication   35.239.63.143   ready   10m

Service per Pod¶

Still, sometimes it is required to expose all MySQL instances, where each of them gets its own IP address (e.g. in case of load balancing implemented on the application level).

This is possible by setting the following options in spec.mysql section.

mysql.expose.enabled enables or disables exposure of MySQL instances,
mysql.expose.type defines the Kubernetes Service object type.

The following example creates a dedicated LoadBalancer Service for each node of the MySQL cluster:

mysql:
  expose:
    enabled: true
    type: LoadBalancer

When the cluster instances are exposed in this way, you can find the corresponding Services with the kubectl get services command:

$ kubectl get services
NAME                     TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)                                                         AGE
...
cluster1-mysql-0         LoadBalancer   10.40.44.110   104.198.16.21   3306:31009/TCP,33062:31319/TCP,33060:30737/TCP,6033:30660/TCP   75s
cluster1-mysql-1         LoadBalancer   10.40.42.5     34.70.170.187   3306:30601/TCP,33062:30273/TCP,33060:30910/TCP,6033:30847/TCP   75s
cluster1-mysql-2         LoadBalancer   10.40.42.158   35.193.50.44    3306:32042/TCP,33062:31576/TCP,33060:31656/TCP,6033:31448/TCP   75s

As you could notice, this command also shows mapped ports the application can use to communicate with MySQL instances (e.g. 3306 for the classic MySQL protocol, or 33060 for MySQL X Protocol useful for operations such as asynchronous calls).

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Last update: 2023-08-31