[Bug]: 5.59.0 modifies capitalization of JSON keys unexpectedly

[alanszlosek]

Terraform Core Version

1.9.2

AWS Provider Version

5.59.0

Affected Resource(s)

• aws_ecs_task_definition
• Any resource where JSON data is or can be used as part of the HCL

Expected Behavior

If Terraform configuration contains an aws_ecs_task_definition with "cpu" in the container_definitions JSON, I expect "cpu" to be present in the JSON within the plan.

I use tools that inspect HCL and the Terraform plan to enforce compliance. For some checks, they need to analyze JSON data from the plan. The new provider changes the capitalization of JSON keys, which breaks JSON analysis.

Actual Behavior

The "cpu" field from the JSON for an ecs task container definition is showing in the plan as "Cpu". The compliance tools I use were configured to look for "cpu", following the AWS JSON schema, so they can't perform the compliance check.

But again, this issue isn't limited to the ECS task definition resource. The problem likely affects any resources where JSON data can be used.

Relevant Error/Panic Output Snippet

# aws_ecs_task_definition.service will be created
  + resource "aws_ecs_task_definition" "service" {
      + arn                   = (known after apply)
      + arn_without_revision  = (known after apply)
      + container_definitions = jsonencode(
            [
              + {
                  + Command                = null
                  + Cpu                    = 10
                  + CredentialSpecs        = null
                  + DependsOn              = null
                  + DisableNetworking      = null
                  + DnsSearchDomains       = null
                  + DnsServers             = null
                  + DockerLabels           = null
                  + DockerSecurityOptions  = null
                  + EntryPoint             = null
                  + Environment            = null
                  + EnvironmentFiles       = null
                  + Essential              = true
                  + ExtraHosts             = null
                  + FirelensConfiguration  = null
                  + HealthCheck            = null
                  + Hostname               = null
                  + Image                  = "alpine"
                  + Interactive            = null
                  + Links                  = null
                  + LinuxParameters        = null
                  + LogConfiguration       = null
                  + Memory                 = 512
                  + MemoryReservation      = null
                  + MountPoints            = null
                  + Name                   = "first"
                  + PortMappings           = [
                      + {
                          + AppProtocol        = ""
                          + ContainerPort      = 80
                          + ContainerPortRange = null
                          + HostPort           = 80
                          + Name               = null
                          + Protocol           = ""
                        },
                    ]
                  + Privileged             = null
                  + PseudoTerminal         = null
                  + ReadonlyRootFilesystem = null
                  + RepositoryCredentials  = null
                  + ResourceRequirements   = null
                  + Secrets                = null
                  + StartTimeout           = null
                  + StopTimeout            = null
                  + SystemControls         = null
                  + Ulimits                = null
                  + User                   = null
                  + VolumesFrom            = null
                  + WorkingDirectory       = null
                },
            ]
        )
      + family                = "service"
      + id                    = (known after apply)
      + network_mode          = (known after apply)
      + revision              = (known after apply)
      + skip_destroy          = false
      + tags_all              = (known after apply)
      + track_latest          = false
    }

Terraform Configuration Files

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.59.0"
    }
  }
}

resource "aws_ecs_task_definition" "service" {
  family = "service"
  container_definitions = jsonencode([
    {
      name      = "first"
      image     = "alpine"
      cpu       = 10
      memory    = 512
      essential = true
      portMappings = [
        {
          containerPort = 80
          hostPort      = 80
        }
      ]
    }
  ])
}

Steps to Reproduce

terraform init followed by terraform plan.

If you modify the HCL to toggle between 5.58.0 and 5.59.0 you can see the change in capitalization.

Debug Output

No response

Panic Output

No response

Important Factoids

Reverting back to 5.58.0 fixes the problem.

References

No response

Would you like to implement a fix?

No

[github-actions]

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[0xabdi]

I can confirm the same exists in version 5.60.0 of the terraform AWS provider.

@ewbankkit what is the ETA for having this fixed? It is currently breaking our policy as code engine that enforces compliance on the terraform plan.

[ewbankkit]

This is caused by the AWS SDK for Go v2 migration of the ECS service (#38016). Previously JSON encoding routines in the AWS SDK for Go v1 were used for conversion of the Terraform configured JSON to the AWS API structures and vice-versa (#38380) and the migration replaced these with Go standard JSON functionality.
With SDK v1 the relevant AWS API ContainerDefinition structure had its own struct tags with initial lowercase field names: https://github.com/aws/aws-sdk-go/blob/d46b35a961c828998b8f0feda7a9437e5490791d/service/ecs/api.go#L8558-L9192.
The equivalent SDK v2 structure, https://github.com/aws/aws-sdk-go-v2/blob/99219561632de13ccd9d1fc800acb574d1212270/service/ecs/types/types.go#L631-L1335, has no struct tags and so the default behavior of uppercasing the field names is used.

[jonnangle]

@ewbankkit thanks for this! Will the provider be reverting to the previous behaviour, or should we plan to migrate to the new uppercased field names?

[ewbankkit]

@jonnangle We will restore the previous (v5.58.0) behavior.

[github-actions]

Warning

This issue has been closed, meaning that any additional comments are hard for our team to see. Please assume that the maintainers will not see them.

Ongoing conversations amongst community members are welcome, however, the issue will be locked after 30 days. Moving conversations to another venue, such as the AWS Provider forum, is recommended. If you have additional concerns, please open a new issue, referencing this one where needed.

[github-actions]

This functionality has been released in v5.61.0 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]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.