Bitnami package for Memcached

Memcached is an high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.

Overview of Memcached⁠

Trademarks: This software listing is packaged by Bitnami. The respective trademarks mentioned in the offering are owned by the respective companies, and use of them does not imply any affiliation or endorsement.

TL;DR

helm install my-release oci://registry-1.docker.io/bitnamicharts/memcached

Looking to use Memcached in production? Try VMware Tanzu Application Catalog⁠, the commercial edition of the Bitnami catalog.

Introduction

This chart bootstraps a Memcached⁠ deployment on a Kubernetes⁠ cluster using the Helm⁠ package manager.

Bitnami charts can be used with Kubeapps⁠ for deployment and management of Helm Charts in clusters.

Prerequisites

• Kubernetes 1.23+
• Helm 3.8.0+

Installing the Chart

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

helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/memcached

These commands deploy Memcached on the Kubernetes cluster in the default configuration. The Parameters section lists the parameters that can be configured during installation.

Configuration and installation details

Resource requests and limits

Bitnami charts allow setting resource requests and limits for all containers inside the chart deployment. These are inside the resources value (check parameter table). Setting requests is essential for production workloads and these should be adapted to your specific use case.

To make this process easier, the chart contains the resourcesPreset values, which automatically sets the resources section according to different presets. Check these presets in the bitnami/common chart⁠. However, in production workloads using resourcesPreset is discouraged as it may not fully adapt to your specific needs. Find more information on container resource management in the official Kubernetes documentation⁠.

Prometheus metrics

This chart can be integrated with Prometheus by setting metrics.enabled to true. This will deploy a sidecar container with memcached_exporter⁠ in all pods and a metrics service, which can be configured under the metrics.service section. This metrics service will have the necessary annotations to be automatically scraped by Prometheus.

Prometheus requirements

It is necessary to have a working installation of Prometheus or Prometheus Operator for the integration to work. Install the Bitnami Prometheus helm chart⁠ or the Bitnami Kube Prometheus helm chart⁠ to easily have a working Prometheus in your cluster.

Integration with Prometheus Operator

The chart can deploy ServiceMonitor objects for integration with Prometheus Operator installations. To do so, set the value metrics.serviceMonitor.enabled=true. Ensure that the Prometheus Operator CustomResourceDefinitions are installed in the cluster or it will fail with the following error:

no matches for kind "ServiceMonitor" in version "monitoring.coreos.com/v1"

Install the Bitnami Kube Prometheus helm chart⁠ for having the necessary CRDs and the Prometheus Operator.

Rolling vs Immutable tags⁠

It is strongly recommended to use immutable tags in a production environment. This ensures your deployment does not change automatically if the same tag is updated with a different image.

Bitnami will release a new chart updating its containers if a new version of the main container, significant changes, or critical vulnerabilities exist.

Update credentials

The Bitnami Memcached chart, when upgrading, reuses the secret previously rendered by the chart or the one specified in auth.existingPasswordSecret. To update credentials, use one of the following:

• Run helm upgrade specifying a new password in auth.password
• Run helm upgrade specifying a new secret in auth.existingPasswordSecret

Use Sidecars and Init Containers

If additional containers are needed in the same pod (such as additional metrics or logging exporters), they can be defined using the sidecars config parameter.

sidecars:
- name: your-image-name
  image: your-image
  imagePullPolicy: Always
  ports:
  - name: portname
    containerPort: 1234

If these sidecars export extra ports, extra port definitions can be added using the service.extraPorts parameter (where available), as shown in the example below:

service:
  extraPorts:
  - name: extraPort
    port: 11311
    targetPort: 11311

If additional init containers are needed in the same pod, they can be defined using the initContainers parameter. Here is an example:

initContainers:
  - name: your-image-name
    image: your-image
    imagePullPolicy: Always
    ports:
      - name: portname
        containerPort: 1234

Learn more about sidecar containers⁠ and init containers⁠.

Set Pod affinity

This chart allows you to set your custom affinity using the affinity parameter(s). Find more information about Pod affinity in the Kubernetes documentation⁠.

As an alternative, you can use the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the bitnami/common⁠ chart. To do so, set the podAffinityPreset, podAntiAffinityPreset, or nodeAffinityPreset parameters.

Backup and restore

To back up and restore Helm chart deployments on Kubernetes, you need to back up the persistent volumes from the source deployment and attach them to a new deployment using Velero⁠, a Kubernetes backup/restore tool. Find the instructions for using Velero in this guide⁠.

Persistence

When using architecture: "high-availability" the Bitnami Memcached⁠ image stores the cache-state at the /cache-state path of the container if enabled.

Persistent Volume Claims (PVCs) are used to keep the data across deployments. This is known to work in GCE, AWS, and minikube.

See the Parameters section to configure the PVC or to disable persistence.

If you encounter errors when working with persistent volumes, refer to our troubleshooting guide for persistent volumes⁠.

Parameters

Global parameters

Common parameters

Memcached parameters

Deployment/Statefulset parameters

Note: the README for this chart is longer than the DockerHub length limit of 25000, so it has been trimmed. The full README can be found at https://github.com/bitnami/charts/blob/main/bitnami/memcached/README.md⁠