Chapter 9. Multicloud Object Gateway bucket replication

Data replication from one Multicloud Object Gateway (MCG) bucket to another MCG bucket provides higher resiliency and better collaboration options. These buckets can be either data buckets or namespace buckets backed by any supported storage solution (S3, Azure, etc.).

A replication policy is composed of a list of replication rules. Each rule defines the destination bucket, and can specify a filter based on an object key prefix. Configuring a complementing replication policy on the second bucket results in bidirectional replication.

Prerequisites

  • A running OpenShift Data Foundation Platform.
  • Access to the Multicloud Object Gateway, see link:Accessing the Multicloud Object Gateway with your applications.

  • Download the Multicloud Object Gateway (MCG) command-line interface: 

    # subscription-manager repos --enable=rh-odf-4-for-rhel-8-x86_64-rpms
# yum install mcg
    Important

    Specify the appropriate architecture for enabling the repositories using the subscription manager. For instance, in case of IBM Power use the following command: 

    # subscription-manager repos --enable=rh-odf-4-for-rhel-8-ppc64le-rpms

  • Alternatively, you can install the mcg package from the OpenShift Data Foundation RPMs found here https://access.redhat.com/downloads/content/547/ver=4/rhel---8/4/x86_64/packages

    Important

    Choose the correct Product Variant according to your architecture.

    Note

    Certain MCG features are only available in certain MCG versions, and the appropriate MCG CLI tool version must be used to fully utilize MCG’s features.

To replicate a bucket, see Replicating a bucket to another bucket.

To set a bucket class replication policy, see Setting a bucket class replication policy.

9.1. Replicating a bucket to another bucket

You can set the bucket replication policy in two ways:

9.1.1. Replicating a bucket to another bucket using the MCG command-line interface

Applications that require a Multicloud Object Gateway (MCG) bucket to have a specific replication policy can create an Object Bucket Claim (OBC) and define the replication policy parameter in a JSON file.

Procedure

  • From the MCG command-line interface, run the following command to create an OBC with a specific replication policy: 

    noobaa obc create <bucket-claim-name> -n openshift-storage --replication-policy /path/to/json-file.json
    <bucket-claim-name>
    Specify the name of the bucket claim.
    /path/to/json-file.json

    Is the path to a JSON file which defines the replication policy.

    Example JSON file: 

    [{ "rule_id": "rule-1", "destination_bucket": "first.bucket", "filter": {"prefix": "repl"}}]
    "prefix"
    Is optional. It is the prefix of the object keys that should be replicated, and you can even leave it empty, for example, {"prefix": ""}.

    Example 9.1. Example

    noobaa obc create my-bucket-claim -n openshift-storage --replication-policy /path/to/json-file.json

9.1.2. Replicating a bucket to another bucket using a YAML

Applications that require a Multicloud Object Gateway (MCG) data bucket to have a specific replication policy can create an Object Bucket Claim (OBC) and add the spec.additionalConfig.replication-policy parameter to the OBC.

Procedure

  • Apply the following YAML: 

    apiVersion: objectbucket.io/v1alpha1
kind: ObjectBucketClaim
metadata:
  name: <desired-bucket-claim>
  namespace: <desired-namespace>
spec:
  generateBucketName: <desired-bucket-name>
  storageClassName: openshift-storage.noobaa.io
  additionalConfig:
    replication-policy: [{ "rule_id": "<rule id>", "destination_bucket": "first.bucket", "filter": {"prefix": "<object name prefix>"}}]
    <desired-bucket-claim>
    Specify the name of the bucket claim.
    <desired-namespace>
    Specify the namespace.
    <desired-bucket-name>
    Specify the prefix of the bucket name.
    "rule_id"
    Specify the ID number of the rule, for example, {"rule_id": "rule-1"}.
    "destination_bucket"
    Specify the name of the destination bucket, for example, {"destination_bucket": "first.bucket"}.
    "prefix"
    Is optional. It is the prefix of the object keys that should be replicated, and you can even leave it empty, for example, {"prefix": ""}.

Additional information

9.2. Setting a bucket class replication policy

It is possible to set up a replication policy that automatically applies to all the buckets created under a certain bucket class. You can do this in two ways:

9.2.1. Setting a bucket class replication policy using the MCG command-line interface

Applications that require a Multicloud Object Gateway (MCG) bucket class to have a specific replication policy can create a bucketclass and define the replication-policy parameter in a JSON file.

It is possible to set a bucket class replication policy for two types of bucket classes:

  • Placement
  • Namespace

Procedure

  • From the MCG command-line interface, run the following command: 

    noobaa -n openshift-storage bucketclass create placement-bucketclass <bucketclass-name> --backingstores <backingstores> --replication-policy=/path/to/json-file.json
    <bucketclass-name>
    Specify the name of the bucket class.
    <backingstores>
    Specify the name of a backingstore. It is possible to pass several backingstores separated by commas.
    /path/to/json-file.json

    Is the path to a JSON file which defines the replication policy.

    Example JSON file: 

    [{ "rule_id": "rule-1", "destination_bucket": "first.bucket", "filter": {"prefix": "repl"}}]
    "prefix"
    Is optional. It is the prefix of the object keys that should be replicated, and you can even leave it empty, for example, {"prefix": ""}.

    Example 9.2. Example

    noobaa -n openshift-storage bucketclass create placement-bucketclass bc --backingstores azure-blob-ns --replication-policy=/path/to/json-file.json

    This example creates a placement bucket class with a specific replication policy defined in the JSON file.

9.2.2. Setting a bucket class replication policy using a YAML

Applications that require a Multicloud Object Gateway (MCG) bucket class to have a specific replication policy can create a bucket class using the spec.replicationPolicy field.

Procedure

  1. Apply the following YAML: 

    apiVersion: noobaa.io/v1alpha1
kind: BucketClass
metadata:
  labels:
    app: <desired-app-label>
  name: <desired-bucketclass-name>
  namespace: <desired-namespace>
spec:
  placementPolicy:
    tiers:
    - backingstores:
      - <backingstore>
      placement: Spread
  replicationPolicy: [{ "rule_id": "<rule id>", "destination_bucket": "first.bucket", "filter": {"prefix": "<object name prefix>"}}]

    This YAML is an example that creates a placement bucket class. Each Object bucket claim (OBC) object that is uploaded to the bucket is filtered based on the prefix and is replicated to first.bucket.

    <desired-app-label>
    Specify a label for the app.
    <desired-bucketclass-name>
    Specify the bucket class name.
    <desired-namespace>
    Specify the namespace in which the bucket class gets created.
    <backingstore>
    Specify the name of a backingstore. It is possible to pass several backingstores.
    "rule_id"
    Specify the ID number of the rule, for example, `{"rule_id": "rule-1"}.
    "destination_bucket"
    Specify the name of the destination bucket, for example, {"destination_bucket": "first.bucket"}.
    "prefix"
    Is optional. It is the prefix of the object keys that should be replicated, and you can even leave it empty, for example, {"prefix": ""}.