Prerequisites to using Redis as a target Limitations of Redis as a target Migrating a database using Redis as the target Specifying endpoint settings for a Redis target

Using Redis as a target for Amazon Database Migration Service

Redis is an open-source in-memory data structure store used as a database, cache, and message broker. Managing data in-memory can result in read or write operations taking less than a millisecond, and hundreds of millions of operations performed each second. As an in-memory data store, Redis powers the most demanding applications requiring sub-millisecond response times.

Using Amazon DMS, you can migrate data from any supported source database to a target Redis data store with minimal downtime. For additional information about Redis see, Redis Documentation.

In addition to on-premises Redis, Amazon Database Migration Service supports the following:

Amazon ElastiCache for Redis as a target data store. ElastiCache for Redis works with your Redis clients and uses the open Redis data format to store your data.
Amazon MemoryDB for Redis as a target data store. MemoryDB is compatible with Redis and enables you to build applications using all the Redis data structures, APIs, and commands in use today.

For additional information about working with Redis as a target for Amazon DMS, see the following sections:

Topics

Prerequisites for using a Redis cluster as a target for Amazon DMS
Limitations when using Redis as a target for Amazon Database Migration Service
Migrating data from a relational or non-relational database to a Redis target
Specifying endpoint settings for Redis as a target

Prerequisites for using a Redis cluster as a target for Amazon DMS

DMS supports an on-premises Redis target in a standalone configuration, or as a Redis cluster where data is automatically sharded across multiple nodes. Sharding is the process of separating data into smaller chunks called shards that are spread across multiple servers or nodes. In effect, a shard is a data partition that contains a subset of the total data set, and serves a slice of the overall workload.

Since Redis is a key-value NoSQL data store, the Redis key naming convention to use when your source is a relational database, is schema-name.table-name.primary-key. In Redis, the key and value must not contain the special character %. Otherwise, DMS skips the record.

Note

If you are using ElastiCache for Redis as a target, DMS supports cluster mode enabled configurations only. For more information about using ElastiCache for Redis version 6.x or higher to create a cluster mode enabled target data store, see Getting started in the Amazon ElastiCache for Redis User Guide.

Before you begin a database migration, launch your Redis cluster with the following criteria.

Your cluster has one or more shards.
If you're using an ElastiCache for Redis target, ensure that your cluster doesn't use IAM role-based access control. Instead, use Redis Auth to authenticate users.
Enable Multi-AZ (Availability Zones).
Ensure the cluster has sufficient memory available to fit the data to be migrated from your database.
Make sure that your target Redis cluster is clear of all data before starting the initial migration task.

You should determine your security requirements for the data migration prior to creating your cluster configuration. DMS supports migration to target replication groups regardless of their encryption configuration. But you can enable or disable encryption only when you create your cluster configuration.

Limitations when using Redis as a target for Amazon Database Migration Service

The following limitations apply when using Redis as a target:

Since Redis is a key-value no-sql data store, the Redis key naming convention to use when your source is a relational database, is schema-name.table-name.primary-key.
In Redis, the key-value can't contain the special character %. Otherwise, DMS skips the record.
DMS won't migrate rows that contain the % character.
DMS won't migrate fields that contain the % character in the field name.
Full LOB mode is not supported.
A private Certificate Authority (CA) isn’t supported when using ElastiCache for Redis as a target.

Migrating data from a relational or non-relational database to a Redis target

You can migrate data from any source SQL or NoSQL data store directly to a Redis target. Setting up and starting a migration to a Redis target is similar to any full load and change data capture migration using the DMS console or API. To perform a database migration to a Redis target, you do the following.

Create a replication instance to perform all the processes for the migration. For more information, see Creating a replication instance.
Specify a source endpoint. For more information, see Creating source and target endpoints.
Locate the DNS name and port number of your cluster.
Download a certificate bundle that you can use to verify SSL connections.
Specify a target endpoint, as described below.
Create a task or set of tasks to define what tables and replication processes you want to use. For more information, see Creating a task.
Migrate data from your source database to your target cluster.

You begin a database migration in one of two ways:

You can choose the Amazon DMS console and perform each step there.
You can use the Amazon Command Line Interface (Amazon CLI). For more information about using the CLI with Amazon DMS, see Amazon CLI for Amazon DMS.

To locate the DNS name and port number of your cluster

Use the following Amazon CLI command to provide the replication-group-id with the name of your replication group.
```
aws elasticache describe-replication-groups --replication-group-id myreplgroup
                        
```
Here, the output shows the DNS name in the Address attribute and the port number in the Port attribute of the primary node in the cluster.
```
 ...
"ReadEndpoint": {
"Port": 6379,
"Address": "myreplgroup-
111.1abc1d.1111.uuu1.cache.example.com"
}
...
                        
```
If you are using MemoryDB for Redis as your target, use the following Amazon CLI command to provide an endpoint address to your Redis cluster.
```
aws memorydb describe-clusters --clusterid clusterid
                        
```

Download a certificate bundle for use to verify SSL connections

Enter the following wget command at the command line. Wget is a free GNU command-line utility tool used to download files from the internet.
```
wget https://s3.aws-api-domain/rds-downloads/rds-combined-ca-bundle.pem
                    
```
Here, aws-api-domain completes the Amazon S3 domain in your Amazon Region required to access the speciﬁed S3 bucket and the rds-combined-ca-bundle.pem ﬁle that it provides.

To create a target endpoint using the Amazon DMS console

This endpoint is for your Redis target that is already running.

On the console, choose Endpoints from the navigation pane and then choose Create Endpoint. The following table describes the settings.

For this option	Do this
Endpoint type	Choose the Target endpoint type.
Endpoint identifier	Enter the name of your endpoint. For example, include the type of endpoint in the name, such as `my-redis-target`.
Target engine	Choose Redis as the type of database engine that you want this endpoint to connect.
Cluster name	Enter the DNS name of your Redis cluster.
Port	Enter the port number of your Redis cluster.
SSL security protocol	Choose either Plain text or SSL encryption. Plain text—This option doesn't provide Transport Layer Security (TLS) encryption for traffic between endpoint and database. SSL encryption—If you choose this option, enter an SSL Certificate Authority (CA) certificate ARN to verify the server’s certificate and make an encrypted connection. For on-premises Redis, DMS supports both public and private Certificate Authority (CA). For ElastiCache for Redis, DMS supports only a public CA.
Authentication type	Choose the type of authentication to perform while connecting to Redis. Options include, None, Authentication role, and Authentication token. If you choose Authentication role, provide an Authentication username and an Authentication password. If you choose Authentication token, provide an Authentication password only.
Replication instance	[Optional] Only if you intend to test your connection, choose the name of the replication instance you previously entered on the Create replication instance page.

When you're finished providing all information for your endpoint, Amazon DMS creates your Redis target endpoint for use during database migration.

For information about creating a migration task and starting your database migration, see Creating a task.

Specifying endpoint settings for Redis as a target

To create or modify a target endpoint, you can use the console or the CreateEndpoint or ModifyEndpoint API operations.

For a Redis target in the Amazon DMS console, specify Endpoint-specific settings on the Create endpoint or Modify endpoint console page.

When using CreateEndpoint and ModifyEndpoint API operations, specify request parameters for the RedisSettings option. The example following shows how to do this using the Amazon CLI.


aws dms create-endpoint --endpoint-identifier my-redis-target
--endpoint-type target --engine-name redis --redis-settings 
'{"ServerName":"sample-test-sample.zz012zz.cluster.eee1.cache.bbbxxx.com","Port":6379,"AuthType":"auth-token", 
 "SslSecurityProtocol":"ssl-encryption", "AuthPassword":"notanactualpassword"}'

{
    "Endpoint": {
        "EndpointIdentifier": "my-redis-target",
        "EndpointType": "TARGET",
        "EngineName": "redis",
        "EngineDisplayName": "Redis",
        "TransferFiles": false,
        "ReceiveTransferredFiles": false,
        "Status": "active",
        "KmsKeyId": "arn:aws:kms:us-east-1:999999999999:key/x-b188188x",
        "EndpointArn": "arn:aws:dms:us-east-1:555555555555:endpoint:ABCDEFGHIJKLMONOPQRSTUVWXYZ",
        "SslMode": "none",
        "RedisSettings": {
            "ServerName": "sample-test-sample.zz012zz.cluster.eee1.cache.bbbxxx.com",
            "Port": 6379,
            "SslSecurityProtocol": "ssl-encryption",
            "AuthType": "auth-token"
        }
    }
}

The --redis-settings parameters follow:

ServerName–(Required) Of type string, specifies the Redis cluster that data will be migrated to, and is in your same VPC.
Port–(Required) Of type number, the port value used to access the endpoint.
SslSecurityProtocol–(Optional) Valid values include plaintext and ssl-encryption. The default is ssl-encryption.

The plaintext option doesn't provide Transport Layer Security (TLS) encryption for traffic between endpoint and database.

Use ssl-encryption to make an encrypted connection. ssl-encryption doesn’t require an SSL Certificate Authority (CA) ARN to verify a server’s certificate, but one can be identified optionally using the SslCaCertificateArn setting. If a certificate authority ARN isn't given, DMS uses the Amazon root CA.

When using an on-premises Redis target, you can use SslCaCertificateArn to import public or private Certificate Authority (CA) into DMS, and provide that ARN for server authentication. A private CA isn’t supported when using ElastiCache for Redis as a target.
AuthType–(Required) Indicates the type of authentication to perform when connecting to Redis. Valid values include none, auth-token, and auth-role.

The auth-token option requires an "AuthPassword" be provided, while the auth-role option requires "AuthUserName" and "AuthPassword" be provided.

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