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PostgresOpsRequest

What is PostgresOpsRequest

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

PostgresOpsRequest CRD Specifications

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

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

Sample PostgresOpsRequest for upgrading database:

apiVersion: ops.kubedb.com/v1alpha1
kind: PostgresOpsRequest
metadata:
  name: pg-ops-upgrade
  namespace: demo
spec:
  databaseRef:
    name: pg-group
  type: Upgrade
  upgrade:
    targetVersion: 8.0.27
status:
  conditions:
  - lastTransitionTime: "2020-06-11T09:59:05Z"
    message: The controller has scaled/upgraded the Postgres successfully
    observedGeneration: 3
    reason: OpsRequestSuccessful
    status: "True"
    type: Successful
  observedGeneration: 3
  phase: Successful

Sample PostgresOpsRequest for horizontal scaling:

apiVersion: ops.kubedb.com/v1alpha1
kind: PostgresOpsRequest
metadata:
  name: myops
  namespace: demo
spec:
  databaseRef:
    name: pg-group
  type: HorizontalScaling  
  horizontalScaling:
    member: 3
status:
  conditions:
  - lastTransitionTime: "2020-06-11T09:59:05Z"
    message: The controller has scaled/upgraded the Postgres successfully
    observedGeneration: 3
    reason: OpsRequestSuccessful
    status: "True"
    type: Successful
  observedGeneration: 3
  phase: Successful

Sample PostgresOpsRequest for vertical scaling:

apiVersion: ops.kubedb.com/v1alpha1
kind: PostgresOpsRequest
metadata:
  name: myops
  namespace: demo
spec:
  databaseRef:
    name: pg-group
  type: VerticalScaling  
  verticalScaling:
    postgres:
      requests:
        memory: "1200Mi"
        cpu: "0.7"
      limits:
        memory: "1200Mi"
        cpu: "0.7"
status:
  conditions:
  - lastTransitionTime: "2020-06-11T09:59:05Z"
    message: The controller has scaled/upgraded the Postgres successfully
    observedGeneration: 3
    reason: OpsRequestSuccessful
    status: "True"
    type: Successful
  observedGeneration: 3
  phase: Successful

Here, we are going to describe the various sections of a PostgresOpsRequest cr.

PostgresOpsRequest Spec

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

spec.databaseRef

spec.databaseRef is a required field that point to the Postgres object where the administrative operations will be applied. This field consists of the following sub-field:

  • spec.databaseRef.name : specifies the name of the Postgres 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 PostgresOpsRequest.

  • Upgrade
  • HorizontalScaling
  • VerticalScaling
  • volumeExpansion
  • Restart
  • Reconfigure
  • ReconfigureTLS

You can perform only one type of operation on a single PostgresOpsRequest CR. For example, if you want to upgrade your database and scale up its replica then you have to create two separate PostgresOpsRequest. At first, you have to create a PostgresOpsRequest for upgrading. Once it is completed, then you can create another PostgresOpsRequest for scaling. You should not create two PostgresOpsRequest simultaneously.

spec.upgrade

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

  • spec.upgrade.targetVersion refers to a PostgresVersion CR that contains the Postgres version information where you want to upgrade.

You can only upgrade between Postgres versions. KubeDB does not support downgrade for Postgres.

spec.horizontalScaling

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

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

spec.verticalScaling

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

  • spec.verticalScaling.postgres indicates the Postgres server resources. It has the below structure:
requests:
  memory: "200Mi"
  cpu: "0.1"
limits:
  memory: "300Mi"
  cpu: "0.2"

Here, when you specify the resource request for Postgres container, 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 Postgres 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.verticalScaling.exporter indicates the exporter container resources. It has the same structure as spec.verticalScaling.postgres and you can scale the resource the same way as postgres container.

You can increase/decrease resources for both postgres container and exporter container on a single PostgresOpsRequest CR.

PostgresOpsRequest Status

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

status.phase

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

Phase Meaning
Successful KubeDB has successfully performed the operation requested in the PostgresOpsRequest
Failed KubeDB has failed the operation requested in the PostgresOpsRequest
Denied KubeDB has denied the operation requested in the PostgresOpsRequest

status.observedGeneration

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

status.conditions

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

  • types specifies the type of the condition. PostgresOpsRequest has the following types of conditions:
Type Meaning
Progressing Specifies that the operation is now progressing
Successful Specifies such a state that the operation on the database has been successful.
HaltDatabase Specifies such a state that the database is halted by the operator
ResumeDatabase Specifies such a state that the database is resumed by the operator
Failure Specifies such a state that the operation on the database has been failed.
Scaling Specifies such a state that the scaling operation on the database has stared
VerticalScaling Specifies such a state that vertical scaling has performed successfully on database
HorizontalScaling Specifies such a state that horizontal scaling has performed successfully on database
Upgrading Specifies such a state that database upgrading operation has stared
UpgradeVersion Specifies such a state that version upgrading on the database have performed successfully
  • The status field is a string, with possible values "True", "False", and "Unknown".
    • status will be "True" if the current transition is succeeded.
    • status will be "False" if the current transition is failed.
    • status will be "Unknown" if the current transition is 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. It has the following possible values:
Reason Meaning
OpsRequestProgressingStarted Operator has started the OpsRequest processing
OpsRequestFailedToProgressing Operator has failed to start the OpsRequest processing
SuccessfullyHaltedDatabase Database is successfully halted by the operator
FailedToHaltDatabase Database is failed to halt by the operator
SuccessfullyResumedDatabase Database is successfully resumed to perform its usual operation
FailedToResumedDatabase Database is failed to resume
DatabaseVersionUpgradingStarted Operator has started upgrading the database version
SuccessfullyUpgradedDatabaseVersion Operator has successfully upgraded the database version
FailedToUpgradeDatabaseVersion Operator has failed to upgrade the database version
HorizontalScalingStarted Operator has started the horizontal scaling
SuccessfullyPerformedHorizontalScaling Operator has successfully performed on horizontal scaling
FailedToPerformHorizontalScaling Operator has failed to perform on horizontal scaling
VerticalScalingStarted Operator has started the vertical scaling
SuccessfullyPerformedVerticalScaling Operator has successfully performed on vertical scaling
FailedToPerformVerticalScaling Operator has failed to perform on vertical scaling
OpsRequestProcessedSuccessfully Operator has completed the operation successfully requested by the OpeRequest cr
  • 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.