vpc: Problem creating multiple managed prefix list entries

[YakDriver]

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Closes #21835

Seems like this should be straightforward but now it's giving a new error. Anyone have thoughts?

Output from acceptance testing:

% make testacc TESTS=TestAccVPCManagedPrefixListEntry_ipv4Multiple PKG=ec2
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 20 -run='TestAccVPCManagedPrefixListEntry_ipv4Multiple'  -timeout 180m
=== RUN   TestAccVPCManagedPrefixListEntry_ipv4Multiple
=== PAUSE TestAccVPCManagedPrefixListEntry_ipv4Multiple
=== CONT  TestAccVPCManagedPrefixListEntry_ipv4Multiple
    vpc_managed_prefix_list_entry_test.go:56: Step 1/1 error: Error running apply: exit status 1
        
        Error: error creating EC2 Managed Prefix List Entry (pl-0a58f0e9573b85871,10.0.1.0/24): PrefixListVersionMismatch: The prefix list has the incorrect version number.
        	status code: 400, request id: 7b4c13b8-9faf-45ba-9164-ff79958af14b
        
          with aws_ec2_managed_prefix_list_entry.test2,
          on terraform_plugin_test.tf line 14, in resource "aws_ec2_managed_prefix_list_entry" "test2":
          14: resource "aws_ec2_managed_prefix_list_entry" "test2" {
        
        
        Error: error creating EC2 Managed Prefix List Entry (pl-0a58f0e9573b85871,10.0.2.0/24): PrefixListVersionMismatch: The prefix list has the incorrect version number.
        	status code: 400, request id: c786e1e0-dfbb-4ed8-ac37-5d7774de506c
        
          with aws_ec2_managed_prefix_list_entry.test3,
          on terraform_plugin_test.tf line 20, in resource "aws_ec2_managed_prefix_list_entry" "test3":
          20: resource "aws_ec2_managed_prefix_list_entry" "test3" {
        
--- FAIL: TestAccVPCManagedPrefixListEntry_ipv4Multiple (19.06s)
FAIL
FAIL	github.com/hashicorp/terraform-provider-aws/internal/service/ec2	20.708s

[windowlistener]

Hi,
I tried moving FindManagedPrefixByID(conn,plID) inside the retry function, and it seems to work fine. The ModifyManagedPrefixListInput requires a CurrentVersion parameter that changes each time the prefix list is modified, this is the cause of the error.

_, err := tfresource.RetryWhenAWSErrCodeEquals(d.Timeout(schema.TimeoutCreate), func() (interface{}, error) {
	
	pl, err := FindManagedPrefixListByID(conn, plID)

	if err != nil {
		return nil, fmt.Errorf("error reading EC2 Managed Prefix List (%s): %w", plID, err)
	}

	input := &ec2.ModifyManagedPrefixListInput{
		AddEntries:     []*ec2.AddPrefixListEntry{addPrefixListEntry},
		CurrentVersion: pl.Version,
		PrefixListId:   aws.String(plID),
	}

	return conn.ModifyManagedPrefixList(input)
}, "IncorrectState","PrefixListVersionMismatch")

[taliesins]

Feels like we should add in in a mutex which locks on plID just before we find the managed prefix list by id. Would be more graceful for large prefix lists.

Something like:
https://github.com/hashicorp/terraform-provider-aws/blob/main/internal/conns/mutexkv.go

[YakDriver]

@windowlistener @taliesins Huge thanks for your thoughts! I've updated the PR with mutexes and better retry logic for both create and delete. I think 🤞 this should resolve the issue. The test works well at the very least.

[github-actions]

This functionality has been released in v4.19.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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