Design overview

The Percona Operator for MySQL automates and simplifies deploying and managing open source MySQL clusters on Kubernetes.

Containers deployed with the Operator include the following components:

• Percona Server for MySQL - a free, fully compatible, enhanced, and open source drop-in replacement for any MySQL database,

• Percona XtraBackup - a hot backup utility for MySQL based servers that doesn’t lock your database during the backup,

• Orchestrator - a replication topology manager for MySQL used when asynchronous replication between MySQL instances is turned on,

• HAProxy - a load balancing and proxy service used when asynchronous replication between MySQL instances is turned on),

• MySQL Router - a proxy solution used when group replication between MySQL instances is turned on,

• Percona Toolkit - a set of tools useful in debugging MySQL Pods.

The design of the Operator is highly bound to Percona Server for MySQL and the high availability implementation based on Orchestrator, which in its turn can be briefly described with the following diagram.

Being a regular MySQL Server instance, each node contains the same set of data synchronized accross nodes. The recommended configuration is to have at least 3 nodes. In a basic setup with this amount of nodes, Percona Server for MySQL provides high availability, continuing to function if you take any of the nodes down.

To provide high availability operator uses node affinity to run Percona Server for MySQL instances on separate worker nodes if possible. If some node fails, the pod in it is automatically re-created on another node.

To provide data storage for stateful applications, Kubernetes uses Persistent Volumes. A PersistentVolumeClaim (PVC) is used to implement the automatic storage provisioning to pods. If a failure occurs, the Container Storage Interface (CSI) should be able to re-mount storage on a different node. The PVC StorageClass must support this feature (Kubernetes and OpenShift support this in versions 1.9 and 3.9 respectively).

The Operator functionality extends the Kubernetes API with PerconaServerMySQL object, and it is implemented as a golang application. Each PerconaServerMySQL object maps to one separate MySQL setup. The Operator listens to all events on the created objects. When a new PerconaServerMySQL object is created, or an existing one undergoes some changes or deletion, the Operator automatically creates/changes/deletes all needed Kubernetes objects with the appropriate settings to provide a proper Percona Server for MySQL operation.

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Last update: 2024-03-22