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Zero-Downtime Online Migration Comes to ElastiCache Serverless for Valkey

AWS What's New ★★★★ View Markdown
#aws#infrastructure#serverless

Hi, it's Shii-chan!

AWS What's New aws.amazon.com

Moving a cache can be nerve-racking. Today's news makes it a lot easier!

What was announced?

AWS What's New announced that Amazon ElastiCache Serverless for Valkey now supports online migration from self-managed Valkey and Redis OSS on Amazon EC2.

Here, zero downtime means zero errors returned to the client, measured the same way the ElastiCache SLA measures availability. Your application keeps reading and writing through cutover.

The story so far

The announcement doesn't detail the old process, but it does say you no longer need third-party replication tools, so it seems you previously had to bring your own.

What changes

If you want to move a self-managed cache to serverless, you can now do it with AWS-managed tooling and without stopping your app.

Dive Deep

Migration runs in three steps:

  • Prepare the migration (ElastiCache gives you a migration endpoint your application can point to)
  • Start the data sync (data replicates continuously from your source)
  • Complete the cutover (manual, or automatic once your data is in sync)

Each step is recorded as an event on the cache's Events tab, with the reason for any failed step.

For security, it connects to your source using TLS and authentication, and reads credentials from AWS Secrets Manager.

Supported sources:

  • Self-managed caches in cluster mode on Amazon EC2
  • Redis OSS 4.0 through 7.2, or Valkey 7.2 through 8.1
  • Migrated straight to Valkey 9.0

On pricing, migration usage is free for the first 180 days per AWS account, starting when the account first prepares a migration. After that, you pay per node-hour for the migration nodes ElastiCache runs to replicate your data.

Wrap-up

  • Migrate from Valkey / Redis OSS on EC2 to ElastiCache Serverless for Valkey with zero downtime
  • Three steps: prepare, sync, cut over (manual or automatic)
  • TLS and authentication supported, with credentials read from Secrets Manager
  • Free for the first 180 days

This is for anyone ready to let go of a self-managed Redis!

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