Getting started with data migration

This quickstart outlines how to deploy Migration Assistant for OpenSearch and execute an existing data migration using Reindex-from-Snapshot (RFS). It uses AWS for illustrative purposes. However, the steps can be modified for use with other cloud providers.

Prerequisites and assumptions

Before using this quickstart, make sure you fulfill the following prerequisites:

Verify that your migration path is supported. Note that we test with the exact versions specified, but you should be able to migrate data on alternative minor versions as long as the major version is supported.
The source cluster must be deployed Amazon Simple Storage Service (Amazon S3) plugin.
The target cluster must be deployed.

The steps in this guide assume the following:

In this guide, a snapshot will be taken and stored in Amazon S3; the following assumptions are made about this snapshot:
- The _source flag is enabled on all indexes to be migrated.
- The snapshot includes the global cluster state (include_global_state is true).
- Shard sizes of up to approximately 80 GB are supported. Larger shards cannot be migrated. If this presents challenges for your migration, contact the migration team.
Migration Assistant will be installed in the same AWS Region and have access to both the source snapshot and target cluster.

Step 1: Install Bootstrap on an Amazon EC2 instance (~10 minutes)

To begin your migration, use the following steps to install a bootstrap box on an Amazon Elastic Compute Cloud (Amazon EC2) instance. The instance uses AWS CloudFormation to create and manage the stack.

Log in to the target AWS account in which you want to deploy Migration Assistant.
From the browser where you are logged in to your target AWS account, right-click here to load the CloudFormation template from a new browser tab.
Follow the CloudFormation stack wizard:
- Stack Name: MigrationBootstrap
- Stage Name: dev
- Choose Next after each step > Acknowledge > Submit.
Verify that the Bootstrap stack exists and is set to CREATE_COMPLETE. This process takes around 10 minutes to complete.

Step 2: Set up Bootstrap instance access (~5 minutes)

Use the following steps to set up Bootstrap instance access:

After deployment, find the EC2 instance ID for the bootstrap-dev-instance.

Create an AWS Identity and Access Management (IAM) policy using the following snippet, replacing <aws-region>, <aws-account>, <stage>, and <ec2-instance-id> with your information:

 {
     "Version": "2012-10-17",
     "Statement": [
         {
             "Effect": "Allow",
             "Action": "ssm:StartSession",
             "Resource": [
                 "arn:aws:ec2:<aws-region>:<aws-account>:instance/<ec2-instance-id>",
                 "arn:aws:ssm:<aws-region>:<aws-account>:document/BootstrapShellDoc-<stage>-<aws-region>"
             ]
         }
     ]
 }

Name the policy, for example, SSM-OSMigrationBootstrapAccess, and then create the policy by selecting Create policy.

Step 3: Log in to Bootstrap and building Migration Assistant (~15 minutes)

Next, log in to Bootstrap and build Migration Assistant using the following steps.

Prerequisites

To use these steps, make sure you fulfill the following prerequisites:

The AWS Command Line Interface (AWS CLI) and AWS Session Manager plugin are installed on your instance.
The AWS credentials are configured (aws configure) for your instance.

Steps

Load AWS credentials into your terminal.

Log in to the instance using the following command, replacing <instance-id> and <aws-region> with your instance ID and Region:

 aws ssm start-session --document-name BootstrapShellDoc-<stage>-<aws-region> --target <instance-id> --region <aws-region> [--profile <profile-name>]

Once logged in, run the following command from the shell of the Bootstrap instance in the /opensearch-migrations directory:
```
 ./initBootstrap.sh && cd deployment/cdk/opensearch-service-migration
```
After a successful build, note the path for infrastructure deployment, which will be used in the next step.

Step 4: Configure and deploy RFS (~20 minutes)

Use the following steps to configure and deploy RFS:

Add the target cluster password to AWS Secrets Manager as an unstructured string. Be sure to copy the secret Amazon Resource Name (ARN) for use during deployment.

From the same shell as the Bootstrap instance, modify the cdk.context.json file located in the /opensearch-migrations/deployment/cdk/opensearch-service-migration directory:

 {
 "migration-assistant": {
     "vpcId": "<TARGET CLUSTER VPC ID>",
     "targetCluster": {
         "endpoint": "<TARGET CLUSTER ENDPOINT>",
         "auth": {
             "type": "basic",
             "username": "<TARGET CLUSTER USERNAME>",
             "passwordFromSecretArn": "<TARGET CLUSTER PASSWORD SECRET>"
         }
     },
     "sourceCluster": {
         "endpoint": "<SOURCE CLUSTER ENDPOINT>",
         "auth": {
             "type": "basic",
             "username": "<TARGET CLUSTER USERNAME>",
             "passwordFromSecretArn": "<TARGET CLUSTER PASSWORD SECRET>"
         }
     },
     "reindexFromSnapshotExtraArgs": "<RFS PARAMETERS (see below)>",
     "stage": "dev",
     "otelCollectorEnabled": true,
     "migrationConsoleServiceEnabled": true,
     "reindexFromSnapshotServiceEnabled": true,
     "migrationAssistanceEnabled": true
 }
 }

The source and target cluster authorization can be configured to have no authorization, basic with a username and password, or sigv4.

Bootstrap the account with the following command:

 cdk bootstrap --c contextId=migration-assistant --require-approval never 

Deploy the stacks:

 cdk deploy "*" --c contextId=migration-assistant --require-approval never --concurrency 5

Verify that all CloudFormation stacks were installed successfully.

RFS parameters

If you’re creating a snapshot using migration tooling, these parameters are automatically configured. If you’re using an existing snapshot, modify the reindexFromSnapshotExtraArgs setting with the following values:

```bash
--s3-repo-uri s3://<bucket-name>/<repo> --s3-region <region> --snapshot-name <name>
```

You will also need to give the migrationconsole and reindexFromSnapshot TaskRoles permissions to the S3 bucket.

Step 5: Deploy Migration Assistant

To deploy Migration Assistant, use the following steps:

Bootstrap the account:

 cdk bootstrap --c contextId=migration-assistant --require-approval never --concurrency 5

Deploy the stacks when cdk.context.json is fully configured:

 cdk deploy "*" --c contextId=migration-assistant --require-approval never --concurrency 3

These commands deploy the following stacks:

Migration Assistant network stack
Reindex-from-snapshot stack
Migration console stack

Step 6: Access the migration console

Run the following command to access the migration console:

./accessContainer.sh migration-console dev <region>

accessContainer.sh is located in /opensearch-migrations/deployment/cdk/opensearch-service-migration/ on the Bootstrap instance. To learn more, see Accessing the migration console.

Step 7: Verify the connection to the source and target clusters

To verify the connection to the clusters, run the following command:

console clusters connection-check

You should receive the following output:

* **Source Cluster:** Successfully connected!
* **Target Cluster:** Successfully connected!

To learn more about migration console commands, see [Migration commands].

Step 8: Create a snapshot

Run the following command to initiate snapshot creation from the source cluster:

console snapshot create [...]

To check the snapshot creation status, run the following command:

console snapshot status [...]

To learn more information about the snapshot, run the following command:

console snapshot status --deep-check [...]

Wait for snapshot creation to complete before moving to step 9.

To learn more about snapshot creation, see [Snapshot Creation].

Step 9: Migrate metadata

Run the following command to migrate metadata:

console metadata migrate [...]

For more information, see Migrating metadata.

Step 10: Migrate documents with RFS

You can now use RFS to migrate documents from your original cluster:

To start the migration from RFS, start a backfill using the following command:
```
 console backfill start
```
(Optional) To speed up the migration, increase the number of documents processed at a simultaneously by using the following command:
```
 console backfill scale <NUM_WORKERS>
```
To check the status of the documentation backfill, use the following command:
```
 console backfill status
```
If you need to stop the backfill process, use the following command:
```
 console backfill stop
```

For more information, see Backfill.

Step 11: Backfill monitoring

Use the following command for detailed monitoring of the backfill process:

console backfill status --deep-check

You should receive the following output:

BackfillStatus.RUNNING
Running=9
Pending=1
Desired=10
Shards total: 62
Shards completed: 46
Shards incomplete: 16
Shards in progress: 11
Shards unclaimed: 5

Logs and metrics are available in Amazon CloudWatch in the OpenSearchMigrations log group.

Step 12: Verify that all documents were migrated

Use the following query in CloudWatch Logs Insights to identify failed documents:

fields @message
| filter @message like "Bulk request succeeded, but some operations failed."
| sort @timestamp desc
| limit 10000

If any failed documents are identified, you can index the failed documents directly as opposed to using RFS.

Prerequisites and assumptions
Step 1: Install Bootstrap on an Amazon EC2 instance (~10 minutes)
Step 2: Set up Bootstrap instance access (~5 minutes)
Step 3: Log in to Bootstrap and building Migration Assistant (~15 minutes)
- Prerequisites
- Steps
Step 4: Configure and deploy RFS (~20 minutes)
- RFS parameters
Step 5: Deploy Migration Assistant
Step 6: Access the migration console
Step 7: Verify the connection to the source and target clusters
Step 8: Create a snapshot
Step 9: Migrate metadata
Step 10: Migrate documents with RFS
Step 11: Backfill monitoring
Step 12: Verify that all documents were migrated

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