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Version: 3.1


Metro and asynchronous disaster recovery (DR) involves migrating Kubernetes resources from a source cluster to a destination cluster. To ensure applications can come up correctly on the destination clusters, you may need to modify resources such as Service, ServiceAccount or ConfigMap to work as intended on your destination cluster. The ResourceTransformation feature allows you to define a set of rules that modify the Kubernetes resources before they are migrated to the destination cluster.

ResourceTransformation is a custom resource (CR) that accepts change rules that stork follows to modify resources from a source cluster before applying them onto a destination cluster.

ResourceTransformation schema

  • Path: the YAML path for a given Kubernetes resource you want to perform an operation on. Provide this in dot notation, e.g. metadata.labels.

  • Value: what value you want to update the selected resource to. For example, if path is spec.replicas, you can specify a value of 4.

  • Type: the currently supported data type you want to update values to. Type can be one of the following:

    | Type | Value | Example |
    | ---- | ----- | ------- |
    | KeyPair | Comma separated key value pair for patching map type in resource specs | a:b,c:d,e:f,g:h <br/> \<key1:value1\>, \<key2:value2\>, … \<keyN:valueN\> |
    | List | Comma separated array element list for patching resource specs | [a,b,c,d] <br/> <val1,val2,…,valN> |
    | Int | Integer type value for updating resources | 0 |
    | String | String type values | “new-val” |
    | Bool | Boolean values for setting path value | True, False |

    Complex types such as Array of KeyPairs is not supported.

  • Operations What operation you want to perform on the given path in an unstructured Kubernetes object:

    • Add: sets a new nested path in an unstructured object specification with value. If path already exists, this will replace the existing value.
    • Modify: updates a nested path in an unstructured resource object with value. If the value is a KeyPair or List type, this will append value to the existing path.
    • Delete: removes the specified nested spec path from an unstructured object.

You can specify multiple paths for the same resource and multiple resources in single ResourceTransformation CR.

ResourceTransformation spec

kind : ResourceTransformation
name: name-of-transform-rules
- paths:
- path: <spec-path-of-k8s-resources-to-modify>
value: <value-to-be-updated-at-above-path>
type: <type-of-value->
operation: <operation-to-perform>
- path: <spec-path-of-k8s-resources-to-modify>
value: <value-to-be-updated-at-above-path>
type: <type-of-value->
operation: <operation-to-perform>
resource: <k8s-resource-version/kind-format>

Supported Resources

Portworx can currently perform transformations on the following resources:

  • ConfigMap
  • Service
  • Secret
  • ServiceAccount
  • Role
  • RoleBinding
  • ClusterRole
  • ClusterRoleBinding
  • Ingress
  • NetworkPolicy
  • Endpoint


The example in this topic modifies all Kubernetes services in the mysql namespace on the destination cluster during the migration based on the migration schedule.

Define the source service object

This Service spec defines the source service object. Note the following:

  • There's currently no metadata.annotations defined in the following service object. Secondly the type of service being used is ClusterIP.
  • metadata.labels contains only the app: mysql key value pair.
apiVersion: v1
kind: Service
name: mysql-service
app: mysql
type: ClusterIP
app: mysql
- name: transport
port: 3306

Create a ResourceTransformation spec

This ResourceTransformation spec does two things when it's called:

  • Changes the type from service to LoadBalancer.
  • Updates metadata.labels, adding the handler: project key value pair to it and replacing app: mysql with app:mysql-2.
  • Adds new metadata.annotations to the service object.
kind : ResourceTransformation
name: mysql-service-transform
namespace: mysql
- paths:
- path: "spec.type"
value: "LoadBalancer"
type: "string"
operation: "modify"
- path: "metadata.labels"
value: "handler:project,app:mysql-2"
type: "keypair"
operation: "modify"
- path: "metadata.annotations"
value: "handler:project,app:mysql-2"
type: "keypair"
operation: "add"
resource: "/v1/Service"

When migrated, Portworx will use the rules defined in this ResourceTransformation spec to modify the object it creates on the destination cluster.

Use the ResourceTransformation Spec

A MigrationSchedule references the ResourceTransformation defined above in the spec.template.spec.transformSpecs field. When it triggers, the MigrationSchedule uses the ResourceTransformation defined above to change the object it deploys on the destination cluster:

kind: MigrationSchedule
name: mysql-migration-transform-interval
Namespace: mysql
schedulePolicyName: migrate-every-5m
# This should be the name of the cluster pair
clusterPair: remoteclusterpair
# If set to false this will migrate only the volumes. No PVCs, apps, etc will be migrated
includeResources: true
# If set to false, the deployments and stateful set replicas will be set to
# 0 on the destination. There will be an annotation with
# "" to store the replica count from the source
startApplications: false
# Update service resource as per transformation specs
- mysql-service-transform
- mysql-1-pvc-mysql-migration-transform-interval
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