Vapora/provisioning/schemas/platform/constraints/README.md

Platform Constraints

Validation rules and predicates for configuration values.

Constraint Files

Common (common.ncl)

General validation rules applicable to all services:

Port constraints:

• valid_port(port) - Check if port is in valid range (1024-65535)

String enumeration constraints:

• valid_log_level(level) - Check against valid log levels
• valid_auth_method(method) - Check against valid auth methods
• valid_storage_backend(backend) - Check against valid backends
• valid_deployment_mode(mode) - Check against deployment modes
• valid_llm_provider(provider) - Check against LLM providers

Numeric constraints:

• valid_budget_threshold(percent) - Check percentage is 0-100
• valid_worker_count(count) - Check worker count is in range
• valid_connection_count(count) - Check connection count is valid

URL constraints:

• valid_url(url) - Check URL has valid protocol scheme

Usage Pattern

let constraints = import "constraints/common.ncl" in

# Validate port
assert constraints.valid_port 8080

# Validate enum
assert constraints.valid_log_level "debug"

# In a record definition (using Nickel contracts)
{
  port | Number | doc "Server port" | {
    predicate = fun p => constraints.valid_port p,
    label = "valid port range"
  } = 8080
}

Constraint Philosophy

Constraints are predicates - functions that return true/false for validation:

• Used in Nickel's contract system: field | Type | {predicate = constraint_fn}
• Enable gradual validation - catch errors at config generation time
• Prevent invalid configurations reaching runtime
• Document valid value ranges inline

References

• Parent: ../README.md
• Validators: ../validators/README.md
• Values: ../values/README.md