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New !literal YAML Function for Template Passthrough

· 2 min read
Erik Osterman
Erik Osterman
Founder @ Cloud Posse

Atmos now supports the !literal YAML function, which preserves values exactly as written without any template processing. This solves a common pain point when passing template syntax to downstream tools like Terraform, Helm, or ArgoCD.

The Problem​

When working with multi-tool pipelines, you often need to pass template-like syntax through Atmos to downstream tools. For example, you might want to pass Helm template expressions or Terraform templatefile() variables. Previously, Atmos would attempt to evaluate these expressions, causing errors or unexpected behavior.

# This would fail - Atmos tries to evaluate {{external.email}}
db_users:
  - "{{external.email}}"

# This would also fail - Atmos tries to evaluate ${hostname}
user_data: "echo ${hostname}"

The workarounds were awkward and error-prone:

# Double braces - fragile and hard to read
db_users:
  - "{{'{{external.email}}'}}"

# Template escaping - verbose
db_users:
  - "{{ `{{external.email}}` }}"

The Solution​

The new !literal function provides a clean, self-documenting way to bypass template processing:

# Clear intent, preserves value exactly
db_users:
  - !literal "{{external.email}}"
  - !literal "{{external.admin}}"

# Works with inline arrays too
users: [!literal "{{user1}}", !literal "{{user2}}"]

Use Cases​

Terraform Variables​

Pass ${var.name} syntax to Terraform templates:

vars:
  user_data_template: !literal "#!/bin/bash\necho ${hostname}"
  config_file: !literal "${var.environment}-config.json"

Helm Values​

Pass Helm template expressions:

vars:
  ingress_annotations: !literal "{{ .Values.ingress.class }}"
  service_name: !literal "{{ .Release.Name }}-api"

ArgoCD ApplicationSets​

Pass ArgoCD generator expressions:

vars:
  config_url: !literal "{{external.config_url}}"
  cluster_name: !literal "{{name}}"

Multiline Scripts​

Works with YAML multiline syntax:

vars:
  startup_script: !literal |
    #!/bin/bash
    echo "Hello ${USER}"
    export CONFIG={{config_path}}

Get Started​

The !literal function is available now. Check out the documentation for more examples and details.