cloud-foundation-fabric/blueprints/gke/patterns/mysql

Highly Available MySQL cluster on GKE

• Architecture
• Usage
  • Prerequisites
• Examples
  • Default MySQL cluster on GKE with Docker Hub connectivity using Fleet Connection endpoint
  • Customized MySQL cluster using Remote Repository and Fleet Connection endpoint
  • Default cluster using provided static IP address
• Variables
• Outputs

Architecture

MySQL cluster is exposed using Regional Internal TCP Passthrough Load Balancer either on random or on provided static IP address. Services are listening on four different ports depending on protocol and intended usage:

• 6446 - read/write access using MySQL protocol (targets primary instance)
• 6447 - read-only access using MySQL protocol (targets any instance)
• 64460 - read/write access using MySQLx protocol (targets primary instance)
• 64470 - read-only access using MySQLx protocol (targets any instance)

Behind Load Balancer there are pods (by default - 2 pods) running MySQL router image that are responsible to route the traffic to proper MySQL cluster member. Router learns about MySQL cluster topology by contacting any MySQL server pod using mysql-bootstrap ClusterIP Service during startup and checks periodically for any changes in topology.

MySQL's instances are provisioned using StatefulSet and their Pod DNS identity is provided by Headless Service mysql. Those DNS names (dbc1-${index}.mysql.${namespace}.svc.cluster.local) are used when configuring the cluster and by MySQL router when connecting to desired instance. By default, there are 3 instances provisioned, which is required minimum to obtain highly available solution. Each instance in StatefulSet attaches Physical Volume to store database which persists removal of the Pod or changing the number of instances. These Physical Volumes are kept even when StatefulSet is removed and require manual removal.

The database admin password is generated in Terraform and stored as a Kubernetes Secret.

mysql-server Pods are spread across different zones using topologySpreadConstraints with maxSkew of 1, minDomains of 3 and Pod antiAffinity preventing the Pods to run on the same host. This permits running two nodes in one zone (but on different hosts) in case of one zone failure in 3-zoned region.

mysql-router Pods hava affinity to run in the same zones as mysql-server nodes and antiAffinity to run on the same host (required) or zone (preferred) as other mysql-router . With two instances of mysql-router this might result in 2 instances running in the same region

Usage

Prerequisites

• GKE cluster is already provisioned and access to it using kubectl is configured. You can use autopilot-cluster blueprint to create such cluster.
• kubectl configuration obtained either by gcloud container clusters get-credentials or gcloud container fleet memberships get-credentials
• Cluster node have access to Oracle images mysql/mysql-server and mysql/mysql-router
• Access to the cluster's API from where terraform is run either using GKE API endpoint of Fleet endpoint. autopilot-cluster blueprint provisions and provides the link to Fleet endpoint.
• (optional) static IP address to be used by LoadBalancer that exposes MySQL

Examples

Default MySQL cluster on GKE with Docker Hub connectivity using Fleet Connection endpoint

credentials_config = {
  fleet_host = "https://connectgateway.googleapis.com/v1/projects/.../locations/global/gkeMemberships/..."  # provided by ../autopilot-cluster blueprint
}

# tftest skip

Customized MySQL cluster using Remote Repository and Fleet Connection endpoint

credentials_config = {
  fleet_host = "https://connectgateway.googleapis.com/v1/projects/.../locations/global/gkeMemberships/..."  # provided by ../autopilot-cluster blueprint
}

registry_path = "europe-west8-docker.pkg.dev/.../..."
mysql_config = {
  db_replicas = 8
  db_cpu           = "750m"
  db_memory        = "2Gi"
  db_database_size = "4Gi"
  router_replicas  = 3
  router_cpu       = "250m"
  router_memory    = "1Gi"
  version          = "8.0.30"
}

# tftest skip

Default cluster using provided static IP address

credentials_config = {
  fleet_host = "https://connectgateway.googleapis.com/v1/projects/.../locations/global/gkeMemberships/..."  # provided by ../autopilot-cluster blueprint
}
mysql_config = {
  ip_address = "10.0.0.2"
}
# tftest skip

Variables

name	description	type	required	default
created_resources	IDs of the resources created by autopilot cluster to be consumed here.	object({…})	✓
credentials_config	Configure how Terraform authenticates to the cluster.	object({…})	✓
project_id	Project to deploy bastion host.	string	✓
region	Region used for cluster and network resources.	string	✓
mysql_config	Configure MySQL server and router instances.	object({…})		{}
namespace	Namespace used for MySQL cluster resources.	string		"mysql1"
registry_path	Repository path for images. Default is to use Docker Hub images.	string		"docker.io"
templates_path	Path where manifest templates will be read from. Set to null to use the default manifests.	string		null

Outputs

name	description	sensitive
mysql_password	Password for the MySQL root user.	✓