Set up RDS-Proxy connection pooler for Gitlab DB

[mvandenburgh]

Sets up the Amazon RDS Proxy service for our gitlab RDS postgres instance. RDS Proxy is essentially an AWS-managed DB connection pooler, similar to PgBouncer. Using this will help avoid the issue we've seen lately where the webservice and/or sidekiq pods rapidly scale up and down due to load, resulting in oversaturation of DB connections and essentially DoS'ing the RDS instance.

See https://aws.amazon.com/rds/proxy/pricing/ for pricing details. For our db.t3.xlarge RDS instance with 4 vCPUs, using RDS Proxy would cost approximately $43.20 a month.

0.015 (cost per hour) * 4 (vCPU count) * 24 (hours) * 30 (days) = 43.20

I've already deployed this to staging, and it works.

References used -

• TF module examples
• AWS db_proxy Terraform provider docs
• I didn't mess with any of the default settings controlling the behavior of the connection pooling, but they are documented here https://registry.terraform.io/modules/terraform-aws-modules/rds-proxy/aws/latest?tab=inputs if we needed to change them.

[jjnesbitt]

Nothing really stands out to me, but I guess I'm just curious about the nature of your testing in staging. Did you just test that the connection can be established through the proxy? Or was there any more testing regarding how it handles load / connection pooling?

[mvandenburgh]

Did you just test that the connection can be established through the proxy?

Yeah, that's all I meant by tested. I haven't done any performance/load testing in staging