[Enhancement]: Add retry support for aws_lambda_invocation (resource and data source)

[theipster]

Description

The purpose of both the aws_lambda_invocation resource and data source are to invoke a Lambda synchronously (i.e. using the RequestResponse invocation type). Furthermore, for synchronous invocations, it is the responsibility of the invoker (i.e. the aws_lambda_invocation resource/data source) to handle retries as appropriate.

This enhancement request is to enable practitioners to configure retry parameters for aws_lambda_invocation.

Use cases

In some (many?) real-world scenarios, infrastructure requirements do not change on a frequent basis. Therefore, when a Terraform workload depends on invoking a Lambda function, it may not be efficient or cost-effective to permanently configure provisioned concurrency on the Lambda function. Unfortunately, this means on the rare occasions that the Terraform workload does need to be run, there is a risk of a cold start, which could result in an aws_lambda_invocation timeout and ultimately a failure of the entire Terraform run - all of which could have easily been contained and handled by the aws_lambda_invocation by retrying the request.

Implementation suggestions

For inspiration, the hashicorp/http provider's http data source supports a retry configuration block.

data "http" "foo" {
  ...

  retry {
    attempts = 2

    max_delay_ms = 2000
    min_delay_ms = 1000
  }
}

Affected Resource(s) and/or Data Source(s)

• aws_lambda_invocation

Potential Terraform Configuration

resource "aws_lambda_invocation" "foo" {
  ...

  retry {
    attempts = 2

    max_delay_ms = 2000
    min_delay_ms = 1000
  }
}

data "aws_lambda_invocation" "foo" {
  ...

  retry {
    attempts = 2

    max_delay_ms = 2000
    min_delay_ms = 1000
  }
}

References

• https://docs.aws.amazon.com/lambda/latest/api/API_Invoke.html#API_Invoke_RequestSyntax
• https://docs.aws.amazon.com/lambda/latest/dg/invocation-retries.html
• https://registry.terraform.io/providers/hashicorp/http/latest/docs/data-sources/http#retry

Would you like to implement a fix?

Yes

[github-actions[bot]]

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[jufemaiz]

Oh I am here for this proposal, but for a slightly different reason.

To be clear, the issue we are having is with an updated lambda function returning a valid update but not quite ready for invocation causing failures in the application of a plan due to:

│ Error: invoking Lambda Function (FUNCTION_NAME): operation error Lambda: Invoke, https response error StatusCode: 409, RequestID: UUID, api error CodeArtifactUserPendingException: ERROR: Lambda is initializing your function. It will be ready to invoke shortly.
--
  | │
  | │   with module.MODULE_NAME.aws_lambda_invocation.RESOURCE_NAME[0],
  | │   on .terraform/modules/MODULE/FILENAME.tf line LINE_NUMBER, in resource "aws_lambda_invocation" "RESOURCE_NAME":
  | │   LINE_NUMBER: resource "aws_lambda_invocation" "RESOURCE_NAME" {
  | │
  | ╵