MySQL

MySQL is one of the most popular database servers in the world. Notable users include Wikipedia, Facebook and Google.

Introduction

This chart bootstraps a single node MySQL deployment on a Kubernetes cluster using the Helm package manager.

Prerequisites

• Kubernetes 1.6+ with Beta APIs enabled
• PV provisioner support in the underlying infrastructure

Installing the Chart

To install the chart with the release name my-release:

$ helm install --name my-release stable/mysql

The command deploys MySQL on the Kubernetes cluster in the default configuration. The configuration section lists the parameters that can be configured during installation.

By default a random password will be generated for the root user. If you'd like to set your own password change the mysqlRootPassword in the values.yaml.

You can retrieve your root password by running the following command. Make sure to replace [YOUR_RELEASE_NAME]:

printf $(printf '\%o' `kubectl get secret [YOUR_RELEASE_NAME]-mysql -o jsonpath="{.data.mysql-root-password[*]}"`)

Tip: List all releases using helm list

Uninstalling the Chart

To uninstall/delete the my-release deployment:

$ helm delete my-release

The command removes all the Kubernetes components associated with the chart and deletes the release.

Configuration

The following tables lists the configurable parameters of the MySQL chart and their default values.

Parameter	Description	Default
imageTag	mysql image tag.	Most recent release
imagePullPolicy	Image pull policy	IfNotPresent
mysqlRootPassword	Password for the root user.	nil
mysqlUser	Username of new user to create.	nil
mysqlPassword	Password for the new user.	nil
mysqlDatabase	Name for new database to create.	nil
livenessProbe.initialDelaySeconds	Delay before liveness probe is initiated	30
livenessProbe.periodSeconds	How often to perform the probe	10
livenessProbe.timeoutSeconds	When the probe times out	5
livenessProbe.successThreshold	Minimum consecutive successes for the probe to be considered successful after having failed.	1
livenessProbe.failureThreshold	Minimum consecutive failures for the probe to be considered failed after having succeeded.	3
readinessProbe.initialDelaySeconds	Delay before readiness probe is initiated	5
readinessProbe.periodSeconds	How often to perform the probe	10
readinessProbe.timeoutSeconds	When the probe times out	1
readinessProbe.successThreshold	Minimum consecutive successes for the probe to be considered successful after having failed.	1
readinessProbe.failureThreshold	Minimum consecutive failures for the probe to be considered failed after having succeeded.	3
persistence.enabled	Create a volume to store data	true
persistence.size	Size of persistent volume claim	8Gi RW
persistence.storageClass	Type of persistent volume claim	nil (uses alpha storage class annotation)
persistence.accessMode	ReadWriteOnce or ReadOnly	ReadWriteOnce
persistence.existingClaim	Name of existing persistent volume	nil
persistence.subPath	Subdirectory of the volume to mount	nil
resources	CPU/Memory resource requests/limits	Memory: 256Mi, CPU: 100m
configurationFiles	List of mysql configuration files	nil

Some of the parameters above map to the env variables defined in the MySQL DockerHub image.

Specify each parameter using the --set key=value[,key=value] argument to helm install. For example,

$ helm install --name my-release \
  --set mysqlRootPassword=secretpassword,mysqlUser=my-user,mysqlPassword=my-password,mysqlDatabase=my-database \
    stable/mysql

The above command sets the MySQL root account password to secretpassword. Additionally it creates a standard database user named my-user, with the password my-password, who has access to a database named my-database.

Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,

$ helm install --name my-release -f values.yaml stable/mysql

Tip: You can use the default values.yaml

Persistence

The MySQL image stores the MySQL data and configurations at the /var/lib/mysql path of the container.

By default a PersistentVolumeClaim is created and mounted into that directory. In order to disable this functionality you can change the values.yaml to disable persistence and use an emptyDir instead.

"An emptyDir volume is first created when a Pod is assigned to a Node, and exists as long as that Pod is running on that node. When a Pod is removed from a node for any reason, the data in the emptyDir is deleted forever."

Custom MySQL configuration files

The MySQL image accepts custom configuration files at the path /etc/mysql/conf.d. If you want to use a customized MySQL configuration, you can create your alternative configuration files by passing the file contents on the configurationFiles attribute. Note that according to the MySQL documentation only files ending with .cfn are loaded.

configurationFiles:
  mysql.cnf: |-
    [mysqld]
    skip-host-cache
    skip-name-resolve
    sql-mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
  mysql_custom.cnf: |-
    [mysqld]