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MemcachedVersion
What is MemcachedVersion
MemcachedVersion is a Kubernetes Custom Resource Definitions (CRD). It provides a declarative configuration to specify the docker images to be used for Memcached database deployed with KubeDB in a Kubernetes native way.
When you install KubeDB, a MemcachedVersion custom resource will be created automatically for every supported Memcached versions. You have to specify the name of MemcachedVersion crd in spec.version field of Memcached crd. Then, KubeDB will use the docker images specified in the MemcachedVersion crd to create your expected database.
Using a separate crd for specifying respective docker images, and pod security policy names allow us to modify the images, and policies independent of KubeDB operator. This will also allow the users to use a custom image for the database.
MemcachedVersion Specification
As with all other Kubernetes objects, a MemcachedVersion needs apiVersion, kind, and metadata fields. It also needs a .spec section.
apiVersion: catalog.kubedb.com/v1alpha1
kind: MemcachedVersion
metadata:
annotations:
meta.helm.sh/release-name: kubedb
meta.helm.sh/release-namespace: kubedb
creationTimestamp: "2024-08-22T13:48:12Z"
generation: 1
labels:
app.kubernetes.io/instance: kubedb
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: kubedb-catalog
app.kubernetes.io/version: v2024.8.21
helm.sh/chart: kubedb-catalog-v2024.8.21
name: 1.6.22
resourceVersion: "2566"
uid: 90041c04-21b8-4b39-a2a6-af2e6a2ccacd
spec:
db:
image: ghcr.io/appscode-images/memcached:1.6.22-alpine
exporter:
image: ghcr.io/appscode-images/memcached_exporter:v0.14.3-ac
podSecurityPolicies:
databasePolicyName: memcached-db
securityContext:
runAsUser: 999
version: 1.6.22
metadata.name
metadata.name is a required field that specifies the name of the MemcachedVersion crd. You have to specify this name in spec.version field of Memcached crd.
We follow this convention for naming MemcachedVersion crd:
- Name format:
{Original Memcached image version}-{modification tag}
We modify original Memcached docker image to support Memcached and re-tag the image with v1, v2 etc. modification tag. An image with higher modification tag will have more features than the images with lower modification tag. Hence, it is recommended to use MemcachedVersion crd with highest modification tag to take advantage of the latest features.
spec.version
spec.version is a required field that specifies the original version of Memcached server that has been used to build the docker image specified in spec.db.image field.
spec.deprecated
spec.deprecated is an optional field that specifies whether the docker images specified here is supported by the current KubeDB operator.
The default value of this field is false. If spec.deprecated is set to true, KubeDB operator will skip processing this CRD object and will add a event to the CRD object specifying that the DB version is deprecated.
spec.db.image
spec.db.image is a required field that specifies the docker image which will be used to create Petset by KubeDB operator to create expected Memcached server.
spec.exporter.image
spec.exporter.image is a required field that specifies the image which will be used to export Prometheus metrics.
spec.podSecurityPolicies.databasePolicyName
spec.podSecurityPolicies.databasePolicyName is a required field that specifies the name of the pod security policy required to get the database server pod(s) running. To use a user-defined policy, the name of the polict has to be set in spec.podSecurityPolicies and in the list of allowed policy names in KubeDB operator like below:
helm upgrade -i kubedb oci://ghcr.io/appscode-charts/kubedb \
--namespace kubedb --create-namespace \
--set additionalPodSecurityPolicies[0]=custom-db-policy \
--set-file global.license=/path/to/the/license.txt \
--wait --burst-limit=10000 --debug