YAMLencode raw output includes escape characters.

[Tim-MacLaughlin-NOAA]

Terraform Version

terraform version
Terraform v1.11.0
on windows_amd64

Terraform Configuration Files

locals {
string = "\\hello\\"
yaml = yamlencode({
    string = "\\hello\\"
    })
}

output "string" {
  value = local.string
}

output "yaml" {
  value = local.yaml
}

Debug Output

2025-03-18T17:57:08.935-0400 [INFO]  Terraform version: 1.11.0
2025-03-18T17:57:08.937-0400 [DEBUG] using github.com/hashicorp/go-tfe v1.70.0
2025-03-18T17:57:08.937-0400 [DEBUG] using github.com/hashicorp/hcl/v2 v2.23.0
2025-03-18T17:57:08.937-0400 [DEBUG] using github.com/hashicorp/terraform-svchost v0.1.1
2025-03-18T17:57:08.937-0400 [DEBUG] using github.com/zclconf/go-cty v1.16.0
2025-03-18T17:57:08.937-0400 [INFO]  Go runtime version: go1.23.3
2025-03-18T17:57:08.937-0400 [INFO]  CLI args: []string{"C:\\Program Files\\Terraform\\terraform.exe", "output", "-raw", "yaml"}
2025-03-18T17:57:08.937-0400 [TRACE] Stdout is a terminal of width 226
2025-03-18T17:57:08.937-0400 [TRACE] Stderr is a terminal of width 226
2025-03-18T17:57:08.937-0400 [TRACE] Stdin is a terminal
2025-03-18T17:57:08.939-0400 [DEBUG] Attempting to open CLI config file: 
2025-03-18T17:57:08.939-0400 [DEBUG] File doesn't exist, but doesn't need to. Ignoring.
2025-03-18T17:57:08.940-0400 [DEBUG] ignoring non-existing provider search directory terraform.d/plugins
2025-03-18T17:57:08.940-0400 [DEBUG] ignoring non-existing provider search directory 
2025-03-18T17:57:08.941-0400 [DEBUG] ignoring non-existing provider search directory 
2025-03-18T17:57:08.941-0400 [INFO]  CLI command args: []string{"output", "-raw", "yaml"}
2025-03-18T17:57:08.942-0400 [TRACE] Meta.Backend: no config given or present on disk, so returning nil config
2025-03-18T17:57:08.942-0400 [TRACE] Meta.Backend: backend has not previously been initialized in this working directory
2025-03-18T17:57:08.942-0400 [TRACE] Meta.Backend: using default local state only (no backend configuration, and no existing initialized backend)
2025-03-18T17:57:08.943-0400 [TRACE] Meta.Backend: instantiated backend of type <nil>
2025-03-18T17:57:08.943-0400 [DEBUG] checking for provisioner in "."
2025-03-18T17:57:08.943-0400 [DEBUG] checking for provisioner in "C:\\Program Files\\Terraform"
2025-03-18T17:57:08.943-0400 [TRACE] Meta.Backend: backend <nil> does not support operations, so wrapping it in a local backend
2025-03-18T17:57:08.943-0400 [TRACE] backend/local: state manager for workspace "default" will:
 - read initial snapshot from terraform.tfstate
 - write new snapshots to terraform.tfstate
 - create any backup at terraform.tfstate.backup
2025-03-18T17:57:08.943-0400 [TRACE] statemgr.Filesystem: reading initial snapshot from terraform.tfstate
2025-03-18T17:57:08.944-0400 [TRACE] statemgr.Filesystem: read snapshot with lineage "2c5cd243-ff23-db0d-fe3a-0a94767070ab" serial 2
"string": "\\hello\\"

Expected Behavior

The raw yaml should have removed the escape characters in the same way that the string does.

As it is I can't run the terraform apply without the escape characters, but the output isn't valid.

Actual Behavior

terraform output
string = "\\hello\\"
yaml = <<EOT
"string": "\\hello\\"

EOT

terraform output -raw string
\hello\

terraform output -raw yaml
"string": "\\hello\\"
*The web interface to report this required that I change the double backslashes to quad backslashes to show the output I get from the console.

Steps to Reproduce

1. Terraform Init
2. Terraform apply
3. Terraform output -raw string
4. Terraform output -raw yaml

Additional Context

I am attempting to pass bash commands through yaml to aws_imagebuilder_component data.
When I apply the code with the escape characters that terraform required AWS is receiving the escape characters as part of the command.

References

No response

Generative AI / LLM assisted development?

No response

[liamcervante]

Hi @Tim-MacLaughlin-NOAA. I think this is working correctly. The yamlencode function produces a string that is valid YAML, which includes the escape characters inside the quotations. As it is, you could take the raw string output and put it into a YAML file which could be parsed.

From a different perspective, this is valid YAML: "string": "\\hello\\". This is invalid YAML: "string": "\hello\". If Terraform produced the latter from the YAML encode function, it would definitely be incorrect.

Perhaps you can share your full aws_imagebuilder_component resource, with the exact error it produces?

[Tim-MacLaughlin-NOAA]

It seems like I didn't understand the distinction between the terraform escape strings and the yaml escape strings.

AWS Image Builder is keeping the yaml escape strings in place until it runs on the system, but it does appear to be handling the syntax correctly when the command actually runs.

Sorry for the confusion.

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