[DPC-5295] move "arm64" to a variable so services can incrementally opt in

[lukey-luke]

🎫 Ticket

DPC-5295

🛠 Changes

• moved architecture to function module's variable.tf
  • this means teams can incrementally opt into the ARM64 changes (see example in context below)

ℹ️ Context

• DPC is the first of partner API teams to migrate to arm64 architecture.
• This change to the function module needs to happen before services that call it update the hash. The merge commit of the pull request will have the hash that should be used. See example here: DPC-5295 Update SHA to inherit Lambda function version update #441
• Previously I hardcoded architectures = ["arm64"]
  • Other teams share this function module and it needs to be backwards compatible during the transition period
  • This works for python code in this repository, but doesn't work for code that is compiled for x86
  • DPC will update CI to compile .go code for arm64
    • associated workflows live here: dpc-app/.github/workflows
    • workflow updates will be accompanied by changes in cdap repository to use arm64 for ONLY dpc
    • see example for api-waf-sync below:

module "api_waf_sync_function" {
  source = "github.com/CMSgov/cdap/terraform/modules/function?ref=<new_hash>"

  app          = var.app
  env          = var.env
  architecture = var.app == "dpc" ? "arm64" : "x86_64"
  ...
}

🧪 Validation

Verified that specifying latest function module hash without architecture variables keeps things on x86

• 

Verified arm64 code runs when architecture is specified

• compiled DPC api waf sync from arm64 architecture HERE
• deployed terraform with architecture variable set to "arm64" in the test environment
• manually invoked lambda and verified it executes successfully

aws lambda invoke --function-name dpc-test-api-waf-sync --region us-east-1 response.json

[lukey-luke]

See also draft for updating function module imports to use arm64 for DPC: https://github.com/CMSgov/cdap/pull/443/changes

[mianava]

LGTM. We will switch the default upon teams confirmed migrations.

[Jose-verdance]

LGTM!