Enable running infracost against a terraform.tfstate file about infracost

[ayr-ton]

I've created a new related issue here:

https://gitlab.com/infracost/infracost-gitlab-ci/-/issues/1

[ctrlaltdev]

Bump for that issue - I'm using TerraGrunt and split my infra in a lot of modules and the work around needed are quite painful. Using the tfstate would really help.

[enribd]

Since separating the infrastructure in several tfstates is a best practice in Terraform, it could be nice to process a set of tfstates instead of just one. Also reading them from cloud object storages like a S3 bucket.

[aliscott]

#203 adds a --use-tfstate flag, which might solve this use case.

So in master you can run it with

# if running dev:
make run ARGS="--tfdir=/path/to/code --use-tfstate"

# if running binary:
infracost --tfdir=/path/to/code --use-tfstate

This still needs the terraform binary to run terraform show internally instead of directly reading the state file, which is the recommended way of interacting with the state (https://www.terraform.io/docs/state/index.html#format) and has the added benefit of working with both local and remote states.

From my testing, this is a lot faster than running terraform plan each time 😄

Let me know if this helps.

[alikhajeh1]

@ctrlaltdev / @enribd can you possibly try v0.7.2 (available on brew too), and see if the infracost --tfdir=/path/to/code --use-tfstate option is good enough to close this issue? It works with remote state. I haven't used TerraGrunt much so it would be great if you can create issues with any difficulties you hit with that.

Regarding several tfstates, maybe we can discuss it in #188 as it seems somewhat related.

[ctrlaltdev]

@alikhajeh1 It works fine!
Just used on a couple of modules and I get a nice output back!

Regarding terragrunt, I'll open an issue for that.

[alikhajeh1]

@ctrlaltdev thanks for creating #224, given the interest in that, I've put it at the top of the todo pile in https://github.com/infracost/infracost/projects/2

Closing this issue, new issues can be created for leftovers.