AWS RDS Writer Endpoint vs Reader Endpoint

Question

I created an Amazon Aurora instance in my VPC. When the instance was created, it came with 2 endpoints, a writer and a reader endpoint.

The instance is using a security policy with an ingress rule (Type: All Traffic, Protocol: All, Port: All, Source: 0.0.0.0/0).

I tried both MySQL Workbench and MySQL monitor command interface to connect to the endpoints.

The connection to the Reader endpoint worked but that to the Writer endpoint didn't. The reader endpoint was readonly, so I was unable to build my DB using it.

Any idea?

Because MySQL workbench attempts to read first before allowing you to write — Adam
Since you can't specify different SG / NACLs for reader and writer (atleast not that I know of), I would err on the client side. Was your host able to resolve the writer to an IP? What did nc -w 0 write -p 3306 give? — Robins Tharakan
@RobinsTharakan Thanks. I haven't tested those and I managed to connect to it by recreating new instances a few times. It is just that for some instances it worked but some not. — Hao Chang

maziar maziar · Accepted Answer · 2016-12-28T00:56:18

An aurora cluster instance might be either a writer or a reader. Aurora clusters allow one writer and up to 15 readers. The instance role might change failover happens.

The writer DNS endpoint always resolves to the writer instance, Cluster writer endpoint

The reader endpoint DNS randomly resolves to one of the reader instances with TTL=1.

(Note: It might point to the writer instance only if they are one healthy instance is available in the cluster fleet) Cluster reader endpoint

AWS RDS Writer Endpoint vs Reader Endpoint

1 Answers