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.
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
statscommand to upstream primary cluster. Then, send the response to the client as it as. - Respond with secondary stats when primary endpoint is down.
- Execute same
- If the sent command is
config get cluster- Execute
config get clusterfor upstream primary/secondary clusters and collect the responses. - Then, put the endpoint information together as a single response for the client.
- Execute
- If other commands is sent, Mimikyu just returns
SERVER_ERRORand 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.
See mimikyu --help.
MIT