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ZooKeeperOpsRequest

What is ZooKeeperOpsRequest

ZooKeeperOpsRequest is a Kubernetes Custom Resource Definitions (CRD). It provides a declarative configuration for ZooKeeper administrative operations like database version updating, horizontal scaling, vertical scaling etc. in a Kubernetes native way.

ZooKeeperOpsRequest CRD Specifications

Like any official Kubernetes resource, a ZooKeeperOpsRequest has TypeMeta, ObjectMeta, Spec and Status sections.

Here, some sample ZooKeeperOpsRequest CRs for different administrative operations is given below:

Sample ZooKeeperOpsRequest for updating database:

Let’s assume that you have a KubeDB managed ZooKeeper cluster named zk-quickstart running on your kubernetes with version 3.8.3. Now, You can update it’s version to 3.9.1 using the following manifest.

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: upgrade-topology
  namespace: demo
spec:
  databaseRef:
    name: zk-quickstart
  type: UpdateVersion
  updateVersion:
    targetVersion: 3.9.1

Sample ZooKeeperOpsRequest Objects for Horizontal Scaling of the database Cluster:

You can scale up and down your zookeeper cluster horizontally.

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: horizontal-scale-up
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: zk-quickstart
  horizontalScaling:
    replicas: 5

Sample ZooKeeperOpsRequest Objects for Vertical Scaling of the database cluster:

You can vertically scale up or down your cluster by updating the requested cpu, memory or, by limiting them.

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: zookeeper-vscale
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: zookeeper
  verticalScaling:
    node:
      resources:
        requests:
          cpu: 600m
          memory: 1.2Gi
        limits:
          cpu: 1
          memory: 2Gi

Sample ZooKeeperOpsRequest Objects for Reconfiguring database cluster:

Reconfigure your cluster by applying new configuration via zoo.conf file.

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: myops-reconfigure-config
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: zk-quickstart
  type: Reconfigure
  configuration:
    applyConfig:
      zoo.cfg: |
        max_connections = 300
        read_buffer_size = 1048576        

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: myops-reconfigure-config
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: zk-quickstart
  type: Reconfigure
  configuration:
    removeCustomConfig: true

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: myops-reconfigure-config
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: zk-quickstart
  type: Reconfigure
  configuration:
    configSecret:
      name: new-config-secret

Sample ZooKeeperOpsRequest Objects for Volume Expansion of database cluster:

You can expand ZooKeeper storage volume in both online and offline mode.

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: online-volume-expansion
  namespace: demo
spec:
  type: VolumeExpansion
  databaseRef:
    name: zk-quickstart
  volumeExpansion:
    mode: "Online"
    node: 3Gi

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: offline-volume-expansion
  namespace: demo
spec:
  type: VolumeExpansion
  databaseRef:
    name: zk-quickstart
  volumeExpansion:
    mode: "Offline"
    node: 4Gi

Sample ZooKeeperOpsRequest Objects for Reconfiguring TLS of the database:

You can use this Ops-Request to Add, Update, Remove or Rotate Your certificates used in TLS connectivity.

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: myops-rotate
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: zk-quickstart
  tls:
    rotateCertificates: true

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: zkops-update-issuer
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: zk-quickstart
  tls:
    issuerRef:
      name: zk-new-issuer
      kind: Issuer
      apiGroup: "cert-manager.io"

apiVersion: ops.kubedb.com/v1alpha1
kind: ZooKeeperOpsRequest
metadata:
  name: myops-remove
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: zk-quickstart
  tls:
    remove: true

Here, we are going to describe the various sections of a ZooKeeperOpsRequest crd.

A ZooKeeperOpsRequest object has the following fields in the spec section.

spec.databaseRef

spec.databaseRef is a required field that point to the ZooKeeper object for which the administrative operations will be performed. This field consists of the following sub-field:

• spec.databaseRef.name : specifies the name of the ZooKeeper object.

spec.type

spec.type specifies the kind of operation that will be applied to the database. Currently, the following types of operations are allowed in ZooKeeperOpsRequest.

• Upgrade / UpdateVersion
• HorizontalScaling
• VerticalScaling
• VolumeExpansion
• Reconfigure
• ReconfigureTLS
• Restart

You can perform only one type of operation on a single ZooKeeperOpsRequest CR. For example, if you want to update your database and scale up its replica then you have to create two separate ZooKeeperOpsRequest. At first, you have to create a ZooKeeperOpsRequest for updating. Once it is completed, then you can create another ZooKeeperOpsRequest for scaling.

Note: There is an exception to the above statement. It is possible to specify both spec.configuration & spec.verticalScaling in a OpsRequest of type VerticalScaling.

spec.updateVersion

If you want to update your ZooKeeper version, you have to specify the spec.updateVersion section that specifies the desired version information. This field consists of the following sub-field:

• spec.updateVersion.targetVersion refers to a ZooKeeperVersion CR that contains the ZooKeeper version information where you want to update.

spec.horizontalScaling

If you want to scale-up or scale-down your ZooKeeper cluster or different components of it, you have to specify spec.horizontalScaling section. This field consists of the following sub-field:

• spec.horizontalScaling.replicas indicates the desired number of pods for ZooKeeper cluster after scaling. For example, if your cluster currently has 4 pods, and you want to add additional 2 pods then you have to specify 6 in spec.horizontalScaling.replicas field. Similarly, if you want to remove one pod from the cluster, you have to specify 3 in spec.horizontalScaling.replicas field.

spec.verticalScaling

spec.verticalScaling is a required field specifying the information of ZooKeeper resources like cpu, memory etc. that will be scaled. This field consists of the following sub-fields:

• spec.verticalScaling.node indicates the desired resources for PetSet of ZooKeeper after scaling.

It has the below structure:

requests:
  memory: "600Mi"
  cpu: "0.5"
limits:
  memory: "800Mi"
  cpu: "0.8"

Here, when you specify the resource request, the scheduler uses this information to decide which node to place the container of the Pod on and when you specify a resource limit for the container, the kubelet enforces those limits so that the running container is not allowed to use more of that resource than the limit you set. You can found more details from here.

spec.volumeExpansion

To use the volume expansion feature the storage class must support volume expansion

If you want to expand the volume of your ZooKeeper standalone or cluster, you have to specify spec.volumeExpansion section. This field consists of the following sub-field:

• spec.volumeExpansion.node indicates the desired size for the persistent volume of a ZooKeeper.
• spec.volumeExpansion.mode indicates the mode of volume expansion. It can be online or offline based on the storage class.

All of them refer to Quantity types of Kubernetes.

Example usage of this field is given below:

spec:
  volumeExpansion:
    node: "2Gi"

This will expand the volume size of all the ZooKeeper nodes to 2 GB.

spec.configuration

If you want to reconfigure your Running ZooKeeper cluster or different components of it with new custom configuration, you have to specify spec.configuration section. This field consists of the following sub-field:

• configSecret points to a secret in the same namespace of a ZooKeeper resource, which contains the new custom configurations. If there are any configSecret set before in the database, this secret will replace it.

• applyConfig contains the new custom config as a string which will be merged with the previous configuration.

• applyConfig is a map where key supports 1 values, namely zoo.conf.

  applyConfig:
    zoo.cfg: |
      max_connections = 300
      read_buffer_size = 1048576      

• removeCustomConfig is a boolean field. Specify this field to true if you want to remove all the custom configuration from the deployed ZooKeeper server.

spec.tls

If you want to reconfigure the TLS configuration of your ZooKeeper cluster i.e. add TLS, remove TLS, update issuer/cluster issuer or Certificates and rotate the certificates, you have to specify spec.tls section. This field consists of the following sub-field:

• spec.tls.issuerRef specifies the issuer name, kind and api group.
• spec.tls.certificates specifies the certificates. You can learn more about this field from here.
• spec.tls.rotateCertificates specifies that we want to rotate the certificate of this database.
• spec.tls.remove specifies that we want to remove tls from this database.
• spec.tls.sslMode specifies what will be the ssl mode of the cluster allowed values are: disable,allow,prefer,require,verify-ca,verify-full
• spec.tls.clientAuthMode specifies what will be the client authentication mode of the cluster allowed values are: md5,scram,cert

spec.timeout

As we internally retry the ops request steps multiple times, This timeout field helps the users to specify the timeout for those steps of the ops request (in second). If a step doesn’t finish within the specified timeout, the ops request will result in failure.

spec.apply

This field controls the execution of obsRequest depending on the database state. It has two supported values: Always & IfReady. Use IfReady, if you want to process the opsRequest only when the database is Ready. And use Always, if you want to process the execution of opsReq irrespective of the Database state.

ZooKeeperOpsRequest Status

.status describes the current state and progress of a ZooKeeperOpsRequest operation. It has the following fields:

status.phase

status.phase indicates the overall phase of the operation for this ZooKeeperOpsRequest. It can have the following three values:

Important: Ops-manager Operator can skip an opsRequest, only if its execution has not been started yet & there is a newer opsRequest applied in the cluster. spec.type has to be same as the skipped one, in this case.

status.observedGeneration

status.observedGeneration shows the most recent generation observed by the ZooKeeperOpsRequest controller.

status.conditions

status.conditions is an array that specifies the conditions of different steps of ZooKeeperOpsRequest processing. Each condition entry has the following fields:

• types specifies the type of the condition. ZooKeeperOpsRequest has the following types of conditions:

• The status field is a string, with possible values True, False, and Unknown.
  • status will be True if the current transition succeeded.
  • status will be False if the current transition failed.
  • status will be Unknown if the current transition was denied.
• The message field is a human-readable message indicating details about the condition.
• The reason field is a unique, one-word, CamelCase reason for the condition’s last transition.
• The lastTransitionTime field provides a timestamp for when the operation last transitioned from one state to another.
• The observedGeneration shows the most recent condition transition generation observed by the controller.