Big Changes: AWS Provider Refactor

[YakDriver]

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Relates #21306
Relates #20959
Relates #20431
Relates #19661
Relates #19347
Relates #17893
Relates #17849
Relates #12840

Description

Maintainers and community contributors face an unnecessary layer of difficulty maintaining the code base such as nonresponsive IDEs and the inability to see all project files on GitHub. To address these growing pains, we are planning significant code refactoring of the Terraform AWS Provider. The refactoring will position the provider for better maintainability now and into the future as AWS ever expands its offerings.

What's New

These are highlights of some of the changes.

1. Broken PRs

As with any significant refactor, prior-PRs will be broken. We apologize for the inconvenience and will help you as much as we can to fix them. However, we hope that the benefits of refactoring will far outweigh the inconvenience now.

Examples of changes PRs need:
#21303

Guide to Fixing PRs After Service Packages

2. Where did everything go?

Before, all code lived in the aws directory. Now, you'll find most code under the internal directory. Here's an example of where files have gone:

Before:

.
+-- aws
|   +-- resource_aws_autoscaling_group.go
|   +-- resource_aws_instance.go
|   +-- resource_aws_vpc.go
...

After:

.
+-- internal
|   +-- service
|      +-- autoscaling
|         +-- group.go
|       +-- ec2
|         +-- instance.go
|         +-- vpc.go
...

3. Naming

The names of everything from variables to functions to files are being simplified and cleaned up:

• 99% of the time, you no longer include "AWS" in every name.
• Resource file names do not include "resource" (e.g., instance.go is the instance resource file). Data source do include "data_source" at the end of the file name (e.g., regions_data_source.go).
• You no longer add the service name (e.g., SSM) to every variable, function, and resource in the service. The one exception is acceptance test names (looking through a list of 6000 tests, it is still handy to see the service).

Here are examples of some name changes:

What	Old Name	New Name
File	aws/resource_aws_ssm_patch_group.go	internal/service/ssm/patch_group.go
File	aws/data_source_aws_msk_cluster.go	internal/service/kafka/cluster_data_source.go
Resource	resourceAwsMqBroker()	ResourceBroker()
Data Source	dataSourceAwsLambdaFunction()	DataSourceFunction()
Function	resourceAwsDynamoDbGlobalTableStateRefreshFunc()	resourceGlobalTableStateRefreshFunc()
waiter Function	waiter.AccountAssignmentCreated()	waitAccountAssignmentCreated()
Acceptance Test	TestAccDataSourceAWSSignerSigningJob_basic	TestAccSignerSigningJobDataSource_basic
Acceptance Test	TestAccAWSAcmCertificate_tags	TestAccACMCertificate_tags

4. acctest Package

When writing acceptance tests, many functions you'll use are now in the acctest package. (What was previously called acctest, "github.com/hashicorp/terraform-plugin-sdk/v2/helper/acctest", is now aliased to sdkacctest.)

func TestAccEC2FlowLog_vpcID(t *testing.T) {
	...
	rName := sdkacctest.RandomWithPrefix(acctest.ResourcePrefix)

	resource.ParallelTest(t, resource.TestCase{
		PreCheck:     func() { acctest.PreCheck(t) },
		ErrorCheck:   acctest.ErrorCheck(t, ec2.EndpointsID),
		Providers:    acctest.Providers,
		CheckDestroy: testAccCheckFlowLogDestroy,
		Steps: []resource.TestStep{
			{
				Config: testAccFlowLogConfig_VPCID(rName),
				Check: resource.ComposeTestCheckFunc(
					testAccCheckFlowLogExists(resourceName, &flowLog),
					acctest.MatchResourceAttrRegionalARN(resourceName, "arn", "ec2", regexp.MustCompile(`vpc-flow-log/fl-.+`)),
					resource.TestCheckResourceAttrPair(resourceName, "iam_role_arn", iamRoleResourceName, "arn"),
					...
				),
			},
		},
	})
}

5. Test Packages

Acceptance tests must be in the {service}_test package. For example, TestAccEC2FlowLog_vpcID would be in the ec2_test package. Some unit tests are not in the {service}_test package. To clarify, any test file that imports acctest must be in {service}_test to avoid an import cycle.

One implication of this is that acceptance tests must import their corresponding non-test packages to use its functions or constants. Also, those functions and constants must be exported (i.e., capitalized).

For example, if a test file in internal/service/ec2_test uses a function called superDuper() defined in internal/service/ec2:

1. the test file must import "github.com/terraform-providers/terraform-provider-aws/internal/service/ec2", aliased as tfec2,
2. superDuper() must be exported as SuperDuper(), and
3. the test file must reference SuperDuper() using the import alias, i.e., tfec2.SuperDuper().

6. Running Tests

Tests run a little differently. For example, to run an IAM test:

% TF_ACC=1 go test ./internal/service/iam -v -count 1 -parallel 20 -run='TestAccIAMRole_basic' -timeout=180m

7. Running Sweepers

Running sweepers requires the sweep build tag:

% go test ./internal/sweep -v -tags=sweep -sweep="us-west-2" -sweep-allow-failures -timeout=1h

New or Affected Resource(s)

• all

Potential Terraform Configuration

From a practitioner perspective, the AWS Provider should work the same.

References

• Refactor to Service Packages #21306