add lifecycle rules to elastic filesystem storage layer

[twentylemon]

EFS has an infrequent access storage class, which is quite a bit cheaper than the standard storage class, but you do end up paying for data transfer when you access the data. There's settings on the file system you can configure to have the data within automatically move from standard to infrequent access classes if the data is unused for a set period of time, then back after it is accessed to avoid data transfer costs. See CloudFormation attribute for lifecycle rules.

It may be cheaper to always use infrequent access, given the size of the data we typically request. That may change after ~1y, so probably do the math so see what's up.

[twentylemon]

Can maybe also switch to using S3 as a file system. Storage is a little cheaper infrequent access tier for EFS even.

• https://stackoverflow.com/questions/52041550/mount-s3-bucket-as-filesystem-on-aws-ecs-container
• https://aws.amazon.com/blogs/compute/amazon-ecs-and-docker-volume-drivers-amazon-ebs/
  • for ebs, but should apply similarly for s3fs
• https://rexray.readthedocs.io/en/stable/user-guide/storage-providers/aws/#aws-s3fs

[twentylemon]

We're only storing about 50Mb in EFS still (only /weather uses it). The cost to leave it entirely in standard storage will be $0.01 - $0.02 per month, depending on rounding. I'll leave the issue open, but won't be working on it until we start using the database quite a bit more.