Add LoadBasedAutoscaling to OpsWorks Layer

[xsalazar]

Summary

This PR adds the capability to define load-based autoscaling settings for OpsWorks Layers. These settings will be used for any OpsWorks Instance within the layer defined as a "load"-type Instance as to when to spin them up.

It is worth noting that the AWS API around these settings, sets default values which are non-intuitive and not well documented. By default, right now, these settings are set as follows within the AWS API when creating a brand new OpsWorks Layer from scratch:

$ aws --profile=terraform --region=us-east-1 opsworks describe-load-based-auto-scaling --layer-id=500f9af3-65b9-4d6a-9ed4-3c06d3ec9b14
{
    "LoadBasedAutoScalingConfigurations": [
        {
            "DownScaling": {
                "Alarms": [], 
                "IgnoreMetricsTime": 10, 
                "ThresholdsWaitTime": 10, 
                "InstanceCount": 1, 
                "CpuThreshold": 30.0
            }, 
            "Enable": false, 
            "UpScaling": {
                "Alarms": [], 
                "IgnoreMetricsTime": 5, 
                "ThresholdsWaitTime": 5, 
                "InstanceCount": 1, 
                "CpuThreshold": 80.0
            }, 
            "LayerId": "500f9af3-65b9-4d6a-9ed4-3c06d3ec9b14"
        }
    ]
}

Note the default values, as well as the Enable flag set to false.

Even if you don't want to enable this setting, but try to apply the disabled Threshold values as -1 (disabled), the AWS API will throw an exception:

$ aws --profile=terraform --region=us-east-1 opsworks set-load-based-auto-scaling --layer-id=500f9af3-65b9-4d6a-9ed4-3c06d3ec9b14 --up-scaling CpuThreshold=-1,MemoryThreshold=-1,LoadThreshold=-1

An error occurred (ValidationException) when calling the SetLoadBasedAutoScaling operation: 

This behavior is undocumented, but it seems as if at least one threshold value must be set, even if the load-based autoscaling is disabled all together.

Given this behavior and the limitations around inter-argument dependencies in the language, I have tried to handle as many combinations of incorrect states as best as possible, but it was difficult to find an existing pattern for this type of handling.

Community Note

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Related PRs and Issues

#3165
#2228

Release Notes

Release note for CHANGELOG:

Adds capability to define `load_based_autoscaling` settings for OpsWorks Layers

Test

Output from acceptance testing:

$ make testacc TEST=./aws TESTARGS='-run=TestAccAWSOpsworksCustomLayer_autoscaling'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -count 1 -parallel 20 -run=TestAccAWSOpsworksCustomLayer_autoscaling -timeout 120m
=== RUN   TestAccAWSOpsworksCustomLayer_autoscaling
=== PAUSE TestAccAWSOpsworksCustomLayer_autoscaling
=== CONT  TestAccAWSOpsworksCustomLayer_autoscaling
--- PASS: TestAccAWSOpsworksCustomLayer_autoscaling (67.13s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	67.294s

[hwoarang]

cc @bflad as he did the review on an older PR (#3165) about the exact same issue and the old one is not being worked on anymore.

[zhelding]

Pull request #21306 has significantly refactored the AWS Provider codebase. As a result, most PRs opened prior to the refactor now have merge conflicts that must be resolved before proceeding.

Specifically, PR #21306 relocated the code for all AWS resources and data sources from a single aws directory to a large number of separate directories in internal/service, each corresponding to a particular AWS service. This separation of code has also allowed for us to simplify the names of underlying functions -- while still avoiding namespace collisions.

We recognize that many pull requests have been open for some time without yet being addressed by our maintainers. Therefore, we want to make it clear that resolving these conflicts in no way affects the prioritization of a particular pull request. Once a pull request has been prioritized for review, the necessary changes will be made by a maintainer -- either directly or in collaboration with the pull request author.

For a more complete description of this refactor, including examples of how old filepaths and function names correspond to their new counterparts: please refer to issue #20000.

For a quick guide on how to amend your pull request to resolve the merge conflicts resulting from this refactor and bring it in line with our new code patterns: please refer to our Service Package Refactor Pull Request Guide.

[ewbankkit]

LGTM 🚀.

% make testacc TESTARGS='-run=TestAccOpsWorksCustomLayer_' PKG=opsworks ACCTEST_PARALLELISM=2 
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/opsworks/... -v -count 1 -parallel 2  -run=TestAccOpsWorksCustomLayer_ -timeout 180m
=== RUN   TestAccOpsWorksCustomLayer_basic
=== PAUSE TestAccOpsWorksCustomLayer_basic
=== RUN   TestAccOpsWorksCustomLayer_update
=== PAUSE TestAccOpsWorksCustomLayer_update
=== RUN   TestAccOpsWorksCustomLayer_cloudWatch
=== PAUSE TestAccOpsWorksCustomLayer_cloudWatch
=== RUN   TestAccOpsWorksCustomLayer_loadBasedAutoScaling
=== PAUSE TestAccOpsWorksCustomLayer_loadBasedAutoScaling
=== CONT  TestAccOpsWorksCustomLayer_basic
=== CONT  TestAccOpsWorksCustomLayer_cloudWatch
--- PASS: TestAccOpsWorksCustomLayer_basic (40.65s)
=== CONT  TestAccOpsWorksCustomLayer_update
--- PASS: TestAccOpsWorksCustomLayer_cloudWatch (80.40s)
=== CONT  TestAccOpsWorksCustomLayer_loadBasedAutoScaling
--- PASS: TestAccOpsWorksCustomLayer_update (68.86s)
--- PASS: TestAccOpsWorksCustomLayer_loadBasedAutoScaling (66.39s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/opsworks	150.877s

[ewbankkit]

@xsalazar Thanks for the contribution 🎉 👏.

[xsalazar]

Wow, thanks @ewbankkit for seeing this one through! 🎉

[github-actions]

This functionality has been released in v4.35.0 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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