no-empty-servers

Requires each document to contain a nonempty servers value.

Attribute	Value
Category	Metadata
Maturity	Silver
OpenAPI	Swagger 2.0; OpenAPI 3.0, 3.1, 3.2
Starter	Warning
Lenient–Complete	Error

Intent

Explicit servers tell clients and tooling where the API is available instead of relying on an implicit default.

Flags

• A document missing servers, unless allowMissingServers is true.
• A present servers value that is null or an empty array.

Referenced document locations are preserved in diagnostics.

Does not flag

Documents containing $ref, nonempty server arrays, or missing servers when the option is enabled. Structural validation must catch a non-array non-null value.

See it fail

openapi: 3.0.3
info:
  title: Payments API
  version: 1.0.0
servers: []
paths: {}

Diagnostic: Servers must be a non-empty array.

Fix it

servers:
  - url: https://api.example.com

Configure

Permit OpenAPI's implicit server default while still rejecting an explicitly empty list:

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        no-empty-servers:
          severity: error
          allowMissingServers: true

:::caution Swagger 2.0

Swagger 2.0 uses host, basePath, and schemes, not servers. Disable this rule for Swagger 2.0 inputs.

:::

Nearby: no-server-example.com, no-server-trailing-slash.