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A schema language is a formal language for describing the structure, constraints, and data types of a configuration. Config schemas are defined in a supported schema language to validate config instances before deployment. Currently, the following languages are supported:
  • JSON Schema (draft 2020-12)
  • CUE
  • Opaque (metadata-only schemas that regard all config instances as valid)
The following sections cover key integration points for each language. To learn more about the strengths and weaknesses of each language, check out our blog post comparing JSON Schema, CUE, and Protocol Buffers.
Last modified on August 6, 2026