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Built-in Functions

OpenChoreo provides several built-in CEL functions for common operations in ComponentType and Trait templates.

oc_omit()​

Removes fields from output. Has two distinct behaviors depending on usage context.

Field-level Omission​

When used as a standalone value, removes the entire YAML key from the template:

resources:
  limits:
    memory: ${parameters.memoryLimit}
    cpu: ${has(parameters.cpuLimit) ? parameters.cpuLimit : oc_omit()}
    # When cpuLimit is missing, the entire 'cpu:' line is removed

metadata:
  name: ${metadata.name}
  annotations: ${has(parameters.annotations) ? parameters.annotations : oc_omit()}
  # When annotations is missing, the entire 'annotations:' key is removed

Expression-level Omission​

When used inside a CEL map expression, removes the key from the map:

# Use CEL's optional key syntax for simple optional fields
container: |
  ${{
    "image": parameters.image,
    ?"cpu": parameters.?cpu,
    ?"memory": parameters.?memory
  }}
  # Keys are only included if the value exists

# Use oc_omit() when conditional logic is involved
container: |
  ${{
    "image": parameters.image,
    "cpu": parameters.cpuLimit > 0 ? parameters.cpuLimit : oc_omit(),
    "debug": parameters.environment == "dev" ? true : oc_omit()
  }}
  # Keys are conditionally included based on logic, not just existence

oc_merge(base, override, ...)​

Shallow merge two or more maps. Later maps override earlier ones for conflicting keys.

Parameters:

  • base - Base map
  • override - Map to merge (overrides base)
  • ... - Additional maps (optional)

Returns: Merged map

# Merge default and custom labels
labels: |
  ${oc_merge({"app": metadata.name, "version": "v1"}, parameters.customLabels)}

# Merge multiple maps (later maps take precedence)
config: ${oc_merge(defaults, layer1, layer2, layer3)}

# Common pattern: merge platform labels with user labels
metadata:
  labels: ${oc_merge(metadata.labels, parameters.customLabels)}

oc_generate_name(...args)​

Generate valid Kubernetes resource names with a hash suffix for uniqueness. Converts input to lowercase, replaces invalid characters with hyphens, and appends an 8-character hash.

Parameters:

  • ...args - One or more strings to combine into a name

Returns: Kubernetes-compliant name string (lowercase, alphanumeric, hyphens, max 63 chars)

# Create ConfigMap name with hash
name: ${oc_generate_name(metadata.name, "config", parameters.environment)}
# Result: "myapp-config-prod-a1b2c3d4"

# Handle special characters automatically
name: ${oc_generate_name("My_App", "Service!")}
# Result: "my-app-service-e5f6g7h8"

# Single argument also gets hash
name: ${oc_generate_name("Hello World!")}
# Result: "hello-world-7f83b165"

Notes:

  • The hash is deterministic: same inputs always produce the same output
  • Useful for generating unique names for resources created in forEach loops
  • Ensures names comply with Kubernetes naming requirements

oc_hash(string)​

Generate an 8-character FNV-32a hash from an input string. Useful for creating unique identifiers or suffixes.

Parameters:

  • string - Input string to hash

Returns: 8-character hexadecimal hash string

# Generate hash for volume name uniqueness
volumeName: main-file-mount-${oc_hash(config.mountPath + "/" + config.name)}

# Use in resource naming
suffix: ${oc_hash(parameters.uniqueKey)}

Notes:

  • Hash is deterministic: same input always produces the same output
  • Used internally by oc_generate_name() to create the hash suffix

Usage Examples​

Complete ComponentType Example​

apiVersion: openchoreo.dev/v1alpha1
kind: ComponentType
metadata:
  name: web-service
spec:
  workloadType: deployment

  schema:
    parameters:
      port: "integer | default=8080"
      customLabels: "map<string> | default={}"
      cpuLimit: "string"

  resources:
    - id: deployment
      template:
        apiVersion: apps/v1
        kind: Deployment
        metadata:
          name: ${metadata.name}
          # Merge platform labels with custom labels
          labels: ${oc_merge(metadata.labels, parameters.customLabels)}
        spec:
          template:
            spec:
              containers:
                - name: app
                  image: ${workload.containers["main"].image}
                  resources:
                    limits:
                      # Only include cpu if specified
                      cpu: ${has(parameters.cpuLimit) ? parameters.cpuLimit : oc_omit()}

    # Generate ConfigMaps with unique names
    - id: configs
      forEach: ${parameters.configFiles}
      var: config
      template:
        apiVersion: v1
        kind: ConfigMap
        metadata:
          name: ${oc_generate_name(metadata.name, config.name)}