Mimikyu

Mimikyu is a tiny proxy of ElastiCahce Memceched configuration endpoint designed for safe migration between 2 Memcached clusters.

This implementation is very rough. Please test carefully with your Memcached client before use in production.

How Mimikyu works

Amazon ElasiCahce Memcached has a mechanism for auto-discovery nodes consists of a Memcached cluster. The configuration endpoint provides the feature.

A Memcached client implemented the auto-discovery protocol fetches all node information (endpoint, port, and so on.) from the endpoint by use config get cluster command.

• https://docs.aws.amazon.com/AmazonElastiCache/latest/mem-ug/AutoDiscovery.html
• https://docs.aws.amazon.com/AmazonElastiCache/latest/mem-ug/AutoDiscovery.HowAutoDiscoveryWorks.html

Mimikyu emulates the configuration endpoint. When Mimikyu receives a request from client,

• If the sent command is stats
  • Execute same stats command to upstream primary cluster. Then, send the response to the client as it as.
  • Respond with secondary stats when primary endpoint is down.
• If the sent command is config get cluster
  • Execute config get cluster for upstream primary/secondary clusters and collect the responses.
  • Then, put the endpoint information together as a single response for the client.
• If other commands is sent, Mimikyu just returns SERVER_ERROR and close the connection from client.
• Also Mimikyu returns error when primary and secondary upstream is down or not exist.

As a result, the client of Mimikyu can discover all nodes included primary cluster and secondary cluster. Hence, we can decrease nodes of primary cluster gradually.

Usage

See mimikyu --help.

License

MIT