Review DCR Instance Types

[ioannakok]

We're currently using t4g.small in production:

dotcom-rendering/dotcom-rendering/scripts/deploy/riff-raff.yaml

Lines 16 to 19 in e234547

	CODE:
	InstanceType: t4g.micro
	PROD:
	InstanceType: t4g.small

Do we want to consider other instance types? Frontend uses a different type, as mentioned in #7440.

Things to consider

• What about the reservations we've already made for the year (they happen in March)? We can evaluate now and make the new reservations with what we decide
• If we go for a larger instance, this will unblock the work @arelra has started on turning on cluster mode in DCR instances. See more on why this would be beneficial and the work already done here:
  • SPIKE: pm2 cluster mode load test #8789
  • pm2 cluster mode uses max cpus #8929
  • Turn off cluster mode #9105

Useful docs

• https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/apply_ri.html#ri-normalization-factor

[alinaboghiu]

https://github.com/guardian/dotcom-rendering/blob/main/dotcom-rendering/docs/architecture/029-scaling-policy-decision-record.md