Cloudwatch log group should expire after a set amount of time time in CI

[Jimlinz]

Enabler

So that CI logs are searchable, we want to expire Cloudwatch logs after a [group agreed] set amount of time. Logs created by CI are currently set to never expire. This adds up overtime, making searching difficult (AWS only loads up to 10,000 log groups by default). More logs will be created as the product grows, which will also incur additional costs to keep them forever.

Acceptance Criteria

• Logs expire after X amount of time
• Most recent logs (~ last 3 weeks) are easily searchable via Cloudwatch (AWS Console)

[billgeo]

What about ElasticSearch? Do we need logs stored at all?

[Jimlinz]

Logs going to ElasticSearch is managed here (I think):
https://github.com/linz/elasticsearch-config/tree/master/config/li/ilm