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MongoDBOpsRequest

What is MongoDBOpsRequest

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

MongoDBOpsRequest CRD Specifications

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

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

Sample MongoDBOpsRequest for updating database:

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-update
  namespace: demo
spec:
  type: UpdateVersion
  databaseRef:
    name: mg-standalone
  updateVersion:
    targetVersion: 4.4.26
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample MongoDBOpsRequest Objects for Horizontal Scaling of different component of the database:

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-hscale-configserver
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: mg-sharding
  horizontalScaling:
    shard:
      shards: 3
      replicas: 3
    configServer:
      replicas: 3
    mongos:
      replicas: 2
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-hscale-down-replicaset
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: mg-replicaset
  horizontalScaling:
    replicas: 3
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample MongoDBOpsRequest Objects for Vertical Scaling of different component of the database:

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-vscale-configserver
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: mg-sharding
  verticalScaling:
    configServer:
      resources:
        requests:
          memory: "150Mi"
          cpu: "0.1"
        limits:
          memory: "250Mi"
          cpu: "0.2"
    mongos:
      resources:
        requests:
          memory: "150Mi"
          cpu: "0.1"
        limits:
          memory: "250Mi"
          cpu: "0.2"
    shard:
      resources:
        requests:
          memory: "150Mi"
          cpu: "0.1"
        limits:
          memory: "250Mi"
          cpu: "0.2"
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-vscale-standalone
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: mg-standalone
  verticalScaling:
    standalone:
      resources:
        requests:
          memory: "150Mi"
          cpu: "0.1"
        limits:
          memory: "250Mi"
          cpu: "0.2"
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-vscale-replicaset
  namespace: demo
spec:
  type: VerticalScaling
  databaseRef:
    name: mg-replicaset
  verticalScaling:
    replicaSet:
      resources:
        requests:
          memory: "150Mi"
          cpu: "0.1"
        limits:
          memory: "250Mi"
          cpu: "0.2"
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample MongoDBOpsRequest Objects for Reconfiguring different database components:

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-reconfiugre-data-replicaset
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: mg-replicaset
  configuration:
    replicaSet:
      applyConfig:
        mongod.conf: |- 
          net:
            maxIncomingConnections: 30000
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-reconfiugre-data-shard
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: mg-sharding
  configuration:
    shard:
      applyConfig:
        mongod.conf: |-
          net:
            maxIncomingConnections: 30000          
    configServer:
      applyConfig:
        mongod.conf: |-
          net:
            maxIncomingConnections: 30000          
    mongos:
      applyConfig:
        mongod.conf: |-
          net:
            maxIncomingConnections: 30000          
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-reconfiugre-data-standalone
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: mg-standalone
  configuration:
    standalone:
      applyConfig:
        mongod.conf: |-
          net:
            maxIncomingConnections: 30000          
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-reconfiugre-replicaset
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: mg-replicaset
  configuration:
    replicaSet:
      configSecret:
        name: new-custom-config
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-reconfiugre-shard
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: mg-sharding
  configuration:
    shard:
      configSecret:
        name: new-custom-config
    configServer:
      configSecret:
        name: new-custom-config
    mongos:
      configSecret:
        name: new-custom-config
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-reconfiugre-standalone
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: mg-standalone
  configuration:
    standalone:
      configSecret:
        name: new-custom-config
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample MongoDBOpsRequest Objects for Volume Expansion of different database components:

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-volume-exp-replicaset
  namespace: demo
spec:
  type: VolumeExpansion
  databaseRef:
    name: mg-replicaset
  volumeExpansion:
    mode: "Online"
    replicaSet: 2Gi
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-volume-exp-shard
  namespace: demo
spec:
  type: VolumeExpansion
  databaseRef:
    name: mg-sharding
  volumeExpansion:
    mode: "Online"
    shard: 2Gi
    configServer: 2Gi
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-volume-exp-standalone
  namespace: demo
spec:
  type: VolumeExpansion
  databaseRef:
    name: mg-standalone
  volumeExpansion:
    mode: "Online"
    standalone: 2Gi
status:
  conditions:
    - lastTransitionTime: "2020-08-25T18:22:38Z"
      message: Successfully completed the modification process
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample MongoDBOpsRequest Objects for Reconfiguring TLS of the database:

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-add-tls
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: mg-rs
  tls:
    issuerRef:
      name: mg-issuer
      kind: Issuer
      apiGroup: "cert-manager.io"
    certificates:
      - alias: client
        emailAddresses:
          - [email protected]

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-rotate
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: mg-rs
  tls:
    rotateCertificates: true

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-change-issuer
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: mg-rs
  tls:
    issuerRef:
      name: mg-new-issuer
      kind: Issuer
      apiGroup: "cert-manager.io"

apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
  name: mops-remove
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: mg-rs
  tls:
    remove: true

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

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

spec.databaseRef

spec.databaseRef is a required field that point to the MongoDB 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 MongoDB 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 MongoDBOpsRequest.

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

You can perform only one type of operation on a single MongoDBOpsRequest CR. For example, if you want to update your database and scale up its replica then you have to create two separate MongoDBOpsRequest. At first, you have to create a MongoDBOpsRequest for updating. Once it is completed, then you can create another MongoDBOpsRequest 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 you MongoDB 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 MongoDBVersion CR that contains the MongoDB version information where you want to update.

Have a look on the updateConstraints of the mongodbVersion spec to know which versions are supported for updating from the current version.

kubectl get mgversion <current-version> -o=jsonpath='{.spec.updateConstraints}' | jq

You can only update between MongoDB versions. KubeDB does not support downgrade for MongoDB.

spec.horizontalScaling

If you want to scale-up or scale-down your MongoDB 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 nodes for MongoDB replicaset cluster after scaling. For example, if your cluster currently has 4 replicaset nodes, and you want to add additional 2 nodes then you have to specify 6 in spec.horizontalScaling.replicas field. Similarly, if you want to remove one node from the cluster, you have to specify 3 in spec.horizontalScaling.replicas field.
• spec.horizontalScaling.configServer.replicas indicates the desired number of ConfigServer nodes for Sharded MongoDB cluster after scaling.
• spec.horizontalScaling.mongos.replicas indicates the desired number of Mongos nodes for Sharded MongoDB cluster after scaling.
• spec.horizontalScaling.shard indicates the configuration of shard nodes for Sharded MongoDB cluster after scaling. This field consists of the following sub-field:
  • spec.horizontalScaling.shard.replicas indicates the number of replicas each shard will have after scaling.
  • spec.horizontalScaling.shard.shards indicates the number of shards after scaling

spec.verticalScaling

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

• spec.verticalScaling.standalone indicates the desired resources for standalone MongoDB database after scaling.
• spec.verticalScaling.replicaSet indicates the desired resources for replicaSet of MongoDB database after scaling.
• spec.verticalScaling.mongos indicates the desired resources for Mongos nodes of Sharded MongoDB database after scaling.
• spec.verticalScaling.configServer indicates the desired resources for ConfigServer nodes of Sharded MongoDB database after scaling.
• spec.verticalScaling.shard indicates the desired resources for Shard nodes of Sharded MongoDB database after scaling.
• spec.verticalScaling.exporter indicates the desired resources for the exporter container.
• spec.verticalScaling.arbiter indicates the desired resources for arbiter node of MongoDB database after scaling.
• spec.verticalScaling.coordinator indicates the desired resources for the coordinator container.

All of them has the below structure:

requests:
  memory: "200Mi"
  cpu: "0.1"
limits:
  memory: "300Mi"
  cpu: "0.2"

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 MongoDB cluster or different components of it, you have to specify spec.volumeExpansion section. This field consists of the following sub-field:

• spec.mode specifies the volume expansion mode. Supported values are Online & Offline. The default is Online.
• spec.volumeExpansion.standalone indicates the desired size for the persistent volume of a standalone MongoDB database.
• spec.volumeExpansion.replicaSet indicates the desired size for the persistent volume of replicaSets of a MongoDB database.
• spec.volumeExpansion.configServer indicates the desired size for the persistent volume of the config server of a sharded MongoDB database.
• spec.volumeExpansion.shard indicates the desired size for the persistent volume of shards of a sharded MongoDB database.

All of them refer to Quantity types of Kubernetes.

Example usage of this field is given below:

spec:
  volumeExpansion:
    shard: "2Gi"

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

spec.configuration

If you want to reconfigure your Running MongoDB 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:

• spec.configuration.standalone indicates the desired new custom configuration for a standalone MongoDB database.
• spec.configuration.replicaSet indicates the desired new custom configuration for replicaSet of a MongoDB database.
• spec.configuration.configServer indicates the desired new custom configuration for config servers of a sharded MongoDB database.
• spec.configuration.mongos indicates the desired new custom configuration for the mongos nodes of a sharded MongoDB database.
• spec.configuration.shard indicates the desired new custom configuration for the shard nodes of a sharded MongoDB database.
• spec.verticalScaling.arbiter indicates the desired new custom configuration for arbiter node of MongoDB database after scaling.

All of them has the following sub-fields:

• configSecret points to a secret in the same namespace of a MongoDB 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 3 values, namely mongod.conf, replicaset.json, configuration.js. And value represents the corresponding configurations. For your information, replicaset.json is used to modify replica set configurations, which we see in the output of rs.config(). And configurarion.js is used to apply a js script to configure mongodb at runtime. KubeDB provisioner operator applies these two directly while reconciling.

  applyConfig:
    configuration.js: |
      print("hello world!!!!")      
    replicaset.json: |
      {
        "settings" : {
          "electionTimeoutMillis" : 4000
        }
      }      
    mongod.conf: |
      net:
        maxIncomingConnections: 30000         

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

spec.tls

If you want to reconfigure the TLS configuration of your database 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.readinessCriteria

spec.readinessCriteria is the criteria for checking readiness of a MongoDB pod after restarting it. It has two fields.

• spec.readinessCriteria.oplogMaxLagSeconds defines the maximum allowed lagging time between the primary & secondary.
• spec.readinessCriteria.objectsCountDiffPercentage denotes the maximum allowed object-count-difference between the primary & secondary.

...
spec:
  readinessCriteria:
    oplogMaxLagSeconds: 20
    objectsCountDiffPercentage: 10
...

Exceeding these thresholds results in opsRequest failure. One thing to note that, readinessCriteria field will make impact only if pod restarting is associated with the opsRequest type.

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.

MongoDBOpsRequest Status

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

status.phase

status.phase indicates the overall phase of the operation for this MongoDBOpsRequest. 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 MongoDBOpsRequest controller.

status.conditions

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

• types specifies the type of the condition. MongoDBOpsRequest 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.