Support lifecycle ignore_changes for lambda versions

[rgoomar]

Is your request related to a problem? Please describe.

I'm running into an issue where we use Terraform to define our Lambdas and deploy new versions using a different pipeline (outside of Terraform) and the terraform plan output when using this module gives us a very long list of Objects have changed outside of Terraform block.

For every function we have, it shows something like this:

# module.some_name.module.aws_lambda.aws_lambda_function.this[0] has changed
    ~ resource "aws_lambda_function" "this" {
          id                             = "some_name"
        ~ last_modified                  = "2023-01-18T21:03:26.000+0000" -> "2023-01-30T18:17:27.000+0000"
        ~ qualified_arn                  = "arn:aws:lambda:region:***:function:some-name-production:277" -> "arn:aws:lambda:region:***:function:some-name-production:298"
        ~ source_code_hash               = "+aati4Nv1y5P6ff3sQ" -> "n2GS9AzOGctZsOEATDn2RlkDLc8g="
        ~ source_code_size               = 340626 -> 340701
        ~ version                        = "277" -> "298"
          # (18 unchanged attributes hidden)

          # (3 unchanged blocks hidden)
      }

This makes our terraform plan outputs very noisy and harder to parse. I would like for these to be ignored.

Describe the solution you'd like.

Given we, as consumers of the module can't use the lifecycle ignore_changes block, I was hoping that we could add an input variable that can add those ignore_changes if the intention is to have your function versions be updated elsewhere.

Something like:

lifecycle {
  ignore_changes = [
    last_modified,
    qualified_arn,
    source_code_hash,
    source_code_size,
    version,
  ]
}

Although given that lifecycle arguments can be literal values only, I'm unsure what the best approach here is to basically have this only show up based on an input variable.

[antonbabenko]

Please take a look in this example and make sure that you specify ignore_source_code_hash = true.

[rgoomar]

@antonbabenko That flag is set and we still get these outputs in the plan.

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