no-server-variables-empty-enum

Validates enum on variables in the root servers list.

Attribute	Value
Category	Metadata
Maturity	Baseline
OpenAPI	OpenAPI 3.0, 3.1, 3.2
All rulesets	Error

Intent

A server-variable enum must offer usable choices, and its default must be one of them.

Flags

• A present enum that is not an array or is empty.
• A variable defining both enum and default when the enum does not contain the exact default value.

An invalid non-array enum with a default can produce both findings.

Does not flag

Variables without enum, nonempty enums with no default, or enums containing their default. Only root-level servers are inspected.

See it fail

servers:
  - url: https://{environment}.example.test
    variables:
      environment:
        default: production
        enum: []

Fix it

servers:
  - url: https://{environment}.example.test
    variables:
      environment:
        default: production
        enum: [production, staging]

Configure

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        no-server-variables-empty-enum: warn

Nearby: no-undefined-server-variable.