Memcached
Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.
TL;DR
$ helm repo add bitnami https://charts.bitnami.com/bitnami
$ helm install my-release bitnami/memcached
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. This Helm chart has been tested on top of Bitnami Kubernetes Production Runtime (BKPR). Deploy BKPR to get automated TLS certificates, logging and monitoring for your applications.
Prerequisites
- Kubernetes 1.12+
- Helm 3.1.0
Installing the Chart
To install the chart with the release name my-release:
$ helm repo add bitnami https://charts.bitnami.com/bitnami
$ helm install my-release bitnami/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.
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.
Parameters
The following tables lists the configurable parameters of the Memcached chart and their default values per section/component:
Global parameters
| Parameter | Description | Default |
|---|---|---|
global.imageRegistry |
Global Docker image registry | nil |
global.imagePullSecrets |
Global Docker registry secret names as an array | [] (does not add image pull secrets to deployed pods) |
Common parameters
| Parameter | Description | Default |
|---|---|---|
nameOverride |
String to partially override common.names.fullname | nil |
fullnameOverride |
String to fully override common.names.fullname | nil |
commonLabels |
Labels to add to all deployed objects | {} |
commonAnnotations |
Annotations to add to all deployed objects | {} |
clusterDomain |
Default Kubernetes cluster domain | cluster.local |
extraDeploy |
Array of extra objects to deploy with the release | [] (evaluated as a template) |
Memcached parameters
| Parameter | Description | Default |
|---|---|---|
image.registry |
Memcached image registry | docker.io |
image.repository |
Memcached Image name | bitnami/memcached |
image.tag |
Memcached Image tag | {TAG_NAME} |
image.pullPolicy |
Memcached image pull policy | IfNotPresent |
image.pullSecrets |
Specify docker-registry secret names as an array | [] (does not add image pull secrets to deployed pods) |
architecture |
Memcached architecture. Allowed values: standalone or high-availability | standalone |
replicaCount |
Number of containers | 1 |
command |
Default container command (useful when using custom images) | [] |
arguments |
Default container args (useful when using custom images) | ["/run.sh"] |
extraEnv |
Additional env vars to pass | {} |
hostAliases |
Add deployment host aliases | [] |
memcachedUsername |
Memcached admin user | nil |
memcachedPassword |
Memcached admin password | nil |
service.type |
Kubernetes service type for Memcached | ClusterIP |
service.port |
Memcached service port | 11211 |
service.clusterIP |
Specific cluster IP when service type is cluster IP. Use None for headless service |
nil |
service.nodePort |
Kubernetes Service nodePort | nil |
service.loadBalancerIP |
loadBalancerIP if service type is LoadBalancer |
nil |
service.annotations |
Additional annotations for Memcached service | {} |
resources.requests |
CPU/Memory resource requests | {memory: "256Mi", cpu: "250m"} |
resources.limits |
CPU/Memory resource limits | {} |
portName |
Name of the main port exposed by memcached | memcache |
persistence.enabled |
Enable persistence using PVC (Requires architecture: "high-availability") | true |
persistence.storageClass |
PVC Storage Class for Memcached volume | nil (uses alpha storage class annotation) |
persistence.accessMode |
PVC Access Mode for Memcached volume | ReadWriteOnce |
persistence.size |
PVC Storage Request for Memcached volume | 8Gi |
securityContext.enabled |
Enable security context | true |
securityContext.fsGroup |
Group ID for the container | 1001 |
securityContext.runAsUser |
User ID for the container | 1001 |
securityContext.readOnlyRootFilesystem |
Enable read-only filesystem | false |
podAnnotations |
Pod annotations | {} |
podAffinityPreset |
Pod affinity preset. Ignored if affinity is set. Allowed values: soft or hard |
"" |
podAntiAffinityPreset |
Pod anti-affinity preset. Ignored if affinity is set. Allowed values: soft or hard |
soft |
podLabels |
Add additional labels to the pod (evaluated as a template) | nil |
nodeAffinityPreset.type |
Node affinity preset type. Ignored if affinity is set. Allowed values: soft or hard |
"" |
nodeAffinityPreset.key |
Node label key to match. Ignored if affinity is set. |
"" |
nodeAffinityPreset.values |
Node label values to match. Ignored if affinity is set. |
[] |
affinity |
Affinity for pod assignment | {} (evaluated as a template) |
nodeSelector |
Node labels for pod assignment | {} (evaluated as a template) |
tolerations |
Tolerations for pod assignment | [] (evaluated as a template) |
priorityClassName |
Controller priorityClassName | nil |
serviceAccount.create |
Enable creation of ServiceAccount for memcached pods | true |
serviceAccount.name |
The name of the service account to use. If not set and create is true, a name is generated |
Generated using the memcached.serviceAccountName template |
serviceAccount.automountServiceAccountToken |
Enable/disable auto mounting of the service account token | true |
metrics.enabled |
Start a side-car prometheus exporter | false |
metrics.image.registry |
Memcached exporter image registry | docker.io |
metrics.image.repository |
Memcached exporter image name | bitnami/memcached-exporter |
metrics.image.tag |
Memcached exporter image tag | {TAG_NAME} |
metrics.image.pullPolicy |
Image pull policy | IfNotPresent |
metrics.image.pullSecrets |
Specify docker-registry secret names as an array | [] (does not add image pull secrets to deployed pods) |
metrics.podAnnotations |
Additional annotations for Metrics exporter | {prometheus.io/scrape: "true", prometheus.io/port: "9150"} |
metrics.resources |
Exporter resource requests/limit | {} |
metrics.portName |
Memcached exporter port name | metrics |
metrics.service.type |
Kubernetes service type for Prometheus metrics | ClusterIP |
metrics.service.port |
Prometheus metrics service port | 9150 |
metrics.service.annotations |
Prometheus exporter svc annotations | {prometheus.io/scrape: "true", prometheus.io/port: "9150"} |
The above parameters map to the env variables defined in bitnami/memcached. For more information please refer to the bitnami/memcached image documentation.
Specify each parameter using the --set key=value[,key=value] argument to helm install. For example,
$ helm install my-release --set memcachedUsername=user,memcachedPassword=password bitnami/memcached
The above command sets the Memcached admin account username and password to user and password respectively.
NOTE: Once this chart is deployed, it is not possible to change the application's access credentials, such as usernames or passwords, using Helm. To change these application credentials after deployment, delete any persistent volumes (PVs) used by the chart and re-deploy it, or use the application's built-in administrative tools if available.
Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,
$ helm install my-release -f values.yaml bitnami/memcached
Tip
: You can use the default values.yaml
Configuration and installation details
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.
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 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.
Setting Pod's affinity
This chart allows you to set your custom affinity using the affinity parameter. Find more information about Pod's affinity in the kubernetes documentation.
As an alternative, you can use of 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.
Troubleshooting
Find more information about how to deal with common errors related to Bitnami’s Helm charts in this troubleshooting guide.
Notable changes
4.0.0
Backwards compatibility is not guaranteed unless you modify the labels used on the chart's deployments. Use the workaround below to upgrade from versions previous to 4.0.0. The following example assumes that the release name is memcached:
$ kubectl delete deployment memcached --cascade=false
$ helm upgrade memcached bitnami/memcached
3.0.0
This release uses the new bash based bitnami/memcached container which uses bash scripts for the start up logic of the container and is smaller in size.
Upgrading
To 5.3.0
This version introduces bitnami/common, a library chart as a dependency. More documentation about this new utility could be found here. Please, make sure that you have updated the chart dependencies before executing any upgrade.
To 5.0.0
On November 13, 2020, Helm v2 support was formally finished, this major version is the result of the required changes applied to the Helm Chart to be able to incorporate the different features added in Helm v3 and to be consistent with the Helm project itself regarding the Helm v2 EOL.
What changes were introduced in this major version?
- Previous versions of this Helm Chart use
apiVersion: v1(installable by both Helm 2 and 3), this Helm Chart was updated toapiVersion: v2(installable by Helm 3 only). Here you can find more information about theapiVersionfield. - The different fields present in the Chart.yaml file has been ordered alphabetically in a homogeneous way for all the Bitnami Helm Charts
Considerations when upgrading to this version
- If you want to upgrade to this version from a previous one installed with Helm v3, you shouldn't face any issues
- If you want to upgrade to this version using Helm v2, this scenario is not supported as this version doesn't support Helm v2 anymore
- If you installed the previous version with Helm v2 and wants to upgrade to this version with Helm v3, please refer to the official Helm documentation about migrating from Helm v2 to v3
Useful links
- https://docs.bitnami.com/tutorials/resolve-helm2-helm3-post-migration-issues/
- https://helm.sh/docs/topics/v2_v3_migration/
- https://helm.sh/blog/migrate-from-helm-v2-to-helm-v3/
To 1.0.0
Backwards compatibility is not guaranteed unless you modify the labels used on the chart's deployments. Use the workaround below to upgrade from versions previous to 1.0.0. The following example assumes that the release name is memcached:
$ kubectl patch deployment memcached --type=json -p='[{"op": "remove", "path": "/spec/selector/matchLabels/chart"}]'