Redis

Redis is an advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs.

TL;DR;

$ helm install stable/redis-ha

By default this chart install 3 pods total:

one pod containing a redis master and sentinel container (optional prometheus metrics exporter sidecar available)
two pods each containing a redis slave and sentinel containers (optional prometheus metrics exporter sidecars available)

Introduction

This chart bootstraps a Redis highly available master/slave statefulset in a Kubernetes cluster using the Helm package manager.

Prerequisites

Kubernetes 1.8+ with Beta APIs enabled
PV provisioner support in the underlying infrastructure

Upgrading the Chart

Please note that there have been a number of changes simplifying the redis management strategy (for better failover and elections) in the 3.x version of this chart. These changes allow the use of official redis images that do not require special RBAC or ServiceAccount roles. As a result when upgrading from version >=2.0.1 to >=3.0.0 of this chart, Role, RoleBinding, and ServiceAccount resources should be deleted manually.

Installing the Chart

To install the chart

$ helm install stable/redis-ha

The command deploys Redis on the Kubernetes cluster in the default configuration. By default this chart install one master pod containing redis master container and sentinel container along with 2 redis slave pods each containing their own sentinel sidecars. The configuration section lists the parameters that can be configured during installation.

Tip: List all releases using helm list

Uninstalling the Chart

To uninstall/delete the deployment:

$ helm delete <chart-name>

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

Configuration

The following table lists the configurable parameters of the Redis chart and their default values.

Parameter	Description	Default
`image`	Redis image	`redis`
`tag`	Redis tag	`5.0.5-alpine`
`replicas`	Number of redis master/slave pods	`3`
`serviceAccount.create`	Specifies whether a ServiceAccount should be created	`true`
`serviceAccount.name`	The name of the ServiceAccount to create	Generated using the redis-ha.fullname template
`rbac.create`	Create and use RBAC resources	`true`
`redis.port`	Port to access the redis service	`6379`
`redis.masterGroupName`	Redis convention for naming the cluster group	`mymaster`
`redis.config`	Any valid redis config options in this section will be applied to each server (see below)	see values.yaml
`redis.customConfig`	Allows for custom redis.conf files to be applied. If this is used then `redis.config` is ignored	``
`redis.resources`	CPU/Memory for master/slave nodes resource requests/limits	`{}`
`sentinel.port`	Port to access the sentinel service	`26379`
`sentinel.quorum`	Minimum number of servers necessary to maintain quorum	`2`
`sentinel.config`	Valid sentinel config options in this section will be applied as config options to each sentinel (see below)	see values.yaml
`sentinel.customConfig`	Allows for custom sentinel.conf files to be applied. If this is used then `sentinel.config` is ignored	``
`sentinel.resources`	CPU/Memory for sentinel node resource requests/limits	`{}`
`init.resources`	CPU/Memory for init Container node resource requests/limits	`{}`
`auth`	Enables or disables redis AUTH (Requires `redisPassword` to be set)	`false`
`redisPassword`	A password that configures a `requirepass` and `masterauth` in the conf parameters (Requires `auth: enabled`)	``
`authKey`	The key holding the redis password in an existing secret.	`auth`
`existingSecret`	An existing secret containing a key defined by `authKey` that configures `requirepass` and `masterauth` in the conf parameters (Requires `auth: enabled`, cannot be used in conjunction with `.Values.redisPassword`)	``
`nodeSelector`	Node labels for pod assignment	`{}`
`tolerations`	Toleration labels for pod assignment	`[]`
`hardAntiAffinity`	Whether the Redis server pods should be forced to run on separate nodes.	`true`
`additionalAffinities`	Additional affinities to add to the Redis server pods.	`{}`
`affinity`	Override all other affinity settings with a string.	`""`
`exporter.enabled`	If `true`, the prometheus exporter sidecar is enabled	`false`
`exporter.image`	Exporter image	`oliver006/redis_exporter`
`exporter.tag`	Exporter tag	`v0.31.0`
`exporter.annotations`	Prometheus scrape annotations	`{prometheus.io/path: /metrics, prometheus.io/port: "9121", prometheus.io/scrape: "true"}`
`exporter.extraArgs`	Additional args for the exporter	`{}`
`podDisruptionBudget`	Pod Disruption Budget rules	`{}`
`hostPath.path`	Use this path on the host for data storage	not set
`hostPath.chown`	Run an init-container as root to set ownership on the hostPath	`true`
`sysctlImage.enabled`	Enable an init container to modify Kernel settings	`false`
`sysctlImage.command`	sysctlImage command to execute	[]
`sysctlImage.registry`	sysctlImage Init container registry	`docker.io`
`sysctlImage.repository`	sysctlImage Init container name	`bitnami/minideb`
`sysctlImage.tag`	sysctlImage Init container tag	`latest`
`sysctlImage.pullPolicy`	sysctlImage Init container pull policy	`Always`
`sysctlImage.mountHostSys`	Mount the host `/sys` folder to `/host-sys`	`false`
`schedulerName`	Alternate scheduler name	`nil`

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

$ helm install \
  --set image=redis \
  --set tag=5.0.5-alpine \
    stable/redis-ha

The above command sets the Redis server within default namespace.

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

$ helm install -f values.yaml stable/redis-ha

Tip: You can use the default values.yaml

Custom Redis and Sentinel config options

This chart allows for most redis or sentinel config options to be passed as a key value pair through the values.yaml under redis.config and sentinel.config. See links below for all available options.

Example redis.conf Example sentinel.conf

For example repl-timeout 60 would be added to the redis.config section of the values.yaml as:

    repl-timeout: "60"

Sentinel options supported must be in the the sentinel <option> <master-group-name> <value> format. For example, sentinel down-after-milliseconds 30000 would be added to the sentinel.config section of the values.yaml as:

    down-after-milliseconds: 30000

If more control is needed from either the redis or sentinel config then an entire config can be defined under redis.customConfig or sentinel.customConfig. Please note that these values will override any configuration options under their respective section. For example, if you define sentinel.customConfig then the sentinel.config is ignored.

Host Kernel Settings

Redis may require some changes in the kernel of the host machine to work as expected, in particular increasing the somaxconn value and disabling transparent huge pages. To do so, you can set up a privileged initContainer with the sysctlImage config values, for example:

sysctlImage:
  enabled: true
  mountHostSys: true
  command:
    - /bin/sh
    - -c
    - |-
      install_packages systemd
      sysctl -w net.core.somaxconn=10000
      echo never > /host-sys/kernel/mm/transparent_hugepage/enabled

mikejamesowen/redis-cluster-ha