template

func CustomFunctions ¶

func CustomFunctions() []cel.EnvOption

CustomFunctions returns the CEL environment options for custom template functions.

These functions provide additional capabilities beyond the standard CEL-go extensions, designed for use in CEL-based templates throughout OpenChoreo. All custom functions use the "oc_" prefix to avoid potential conflicts with upstream CEL-go.

Available Functions ¶

oc_omit() - Remove fields, map keys, or array items from rendered output

oc_merge(map1, map2, ...mapN) - Shallow merge of multiple maps

oc_generate_name(...strings) - Generate valid Kubernetes resource names

oc_hash(string) - Generate 8-character hash from input string

oc_omit() - Conditional Omission ¶

Returns a sentinel value that is removed during post-processing. Supports two use cases:

Use Case 1: Remove entire fields from YAML/JSON structure

metadata:
  annotations: ${has(spec.annotations) ? spec.annotations : oc_omit()}
  labels:
    version: ${has(spec.version) ? spec.version : oc_omit()}

Result when spec.annotations and spec.version are undefined:

metadata:
  labels: {}

Use Case 2: Remove map keys or array items within CEL expressions

# Conditional map keys
labels: ${{"app": metadata.name, "env": has(spec.env) ? spec.env : oc_omit()}}

# Conditional array items
args: ${["--port=8080", spec.debug ? "--debug" : oc_omit(), "--log=info"]}

oc_merge() - Shallow Map Merge ¶

Merges multiple maps left-to-right, with later maps overriding earlier ones. IMPORTANT: This is a shallow merge - nested maps are replaced, not merged recursively.

# Basic merge
env: ${oc_merge(defaults, spec.env, envOverrides)}

# Inline map literals
resources: ${oc_merge({cpu: "100m", memory: "128Mi"}, spec.resources)}

# Variadic merge (3+ maps)
config: ${oc_merge(base, layer1, layer2, layer3)}

Shallow merge behavior:

base = {resources: {cpu: "100m", memory: "128Mi"}, replicas: 1}
override = {resources: {cpu: "200m"}}
result = {resources: {cpu: "200m"}, replicas: 1}
# Note: memory is LOST because resources map was replaced entirely

oc_generate_name() - Kubernetes Name Generation ¶

Generates valid Kubernetes DNS subdomain names from arbitrary strings. Names are sanitized, truncated to 253 characters, and include an 8-character hash suffix for uniqueness.

# Variadic arguments
name: ${oc_generate_name(component.name, environment, "cache")}
# "payment-service", "prod", "cache" -> "payment-service-prod-cache-a1b2c3d4"

# Array input
name: ${oc_generate_name([metadata.namespace, metadata.name, "worker"])}

# Single string (sanitized)
name: ${oc_generate_name("My App!")}
# "My App!" -> "my-app-e5f6g7h8"

Hash suffix ensures uniqueness even when inputs sanitize to the same string:

oc_generate_name("my-app")   -> "my-app-abc12345"
oc_generate_name("My App!")  -> "my-app-def67890"  # Different hash

oc_hash() - String Hashing ¶

Generates an 8-character hexadecimal hash from an input string using the FNV-32a algorithm. Useful for creating stable, deterministic identifiers or suffixes.

The hash is deterministic - the same input always produces the same output:

oc_hash("test")  -> "4fdcca5d"  # Always produces this hash
oc_hash("test")  -> "4fdcca5d"  # Same input, same output

All custom functions use the "oc_" prefix to avoid potential conflicts with upstream CEL-go.

func IsMissingDataError ¶

func IsMissingDataError(err error) bool

IsMissingDataError checks if an error indicates missing data during CEL evaluation. This handles CEL runtime errors for missing keys and compile-time errors for undefined variables. These errors are used for graceful degradation in optional contexts like includeWhen and where clauses.

CEL returns:

• "no such key: <key>" for missing map keys/fields at runtime
• "undeclared reference to '<var>'" for undefined variables at compile time

func RemoveOmittedFields ¶

func RemoveOmittedFields(data any) any

RemoveOmittedFields walks the rendered tree after CEL evaluation and strips the omit() sentinel. Templates using the reusable `omit()` helper stay compatible with the rendering pipeline's pruning semantics.