Confluent Schema Registry Subjects API

openapi: 3.1.0
info:
  title: Confluent Schema Registry Compatibility Subjects API
  description: The Confluent Schema Registry provides a RESTful interface for storing and retrieving Avro, JSON Schema, and Protobuf schemas. It stores a versioned history of all schemas based on a specified subject name strategy, provides multiple compatibility settings, and allows evolution of schemas according to configured compatibility settings.
  version: 7.6.0
  contact:
    name: Confluent
    url: https://www.confluent.io/
  license:
    name: Confluent Community License
    url: https://www.confluent.io/confluent-community-license/
servers:
- url: http://localhost:8081
  description: Default Schema Registry
tags:
- name: Subjects
paths:
  /subjects:
    get:
      summary: List registered subjects
      operationId: listSubjects
      tags:
      - Subjects
      parameters:
      - name: subjectPrefix
        in: query
        description: Subject name prefix filter
        schema:
          type: string
      - name: deleted
        in: query
        description: Include soft-deleted subjects
        schema:
          type: boolean
          default: false
      responses:
        '200':
          description: List of subject names
          content:
            application/json:
              schema:
                type: array
                items:
                  type: string
        '500':
          description: Internal server error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorMessage'
  /subjects/{subject}/versions:
    get:
      summary: List versions under subject
      operationId: listVersions
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: deleted
        in: query
        schema:
          type: boolean
          default: false
      responses:
        '200':
          description: List of version numbers
          content:
            application/json:
              schema:
                type: array
                items:
                  type: integer
        '404':
          description: Subject not found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorMessage'
    post:
      summary: Register schema under subject
      operationId: registerSchema
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: normalize
        in: query
        schema:
          type: boolean
          default: false
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RegisterSchemaRequest'
      responses:
        '200':
          description: Schema registered (returns global ID)
          content:
            application/json:
              schema:
                type: object
                properties:
                  id:
                    type: integer
        '409':
          description: Incompatible schema
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorMessage'
        '422':
          description: Unprocessable entity (invalid schema)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorMessage'
  /subjects/{subject}/versions/{version}:
    get:
      summary: Get schema by version
      operationId: getSchemaByVersion
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: version
        in: path
        required: true
        description: Version number or 'latest'
        schema:
          type: string
      - name: deleted
        in: query
        schema:
          type: boolean
          default: false
      responses:
        '200':
          description: Schema details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Schema'
        '404':
          description: Subject or version not found
    delete:
      summary: Delete schema version
      operationId: deleteSchemaVersion
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: version
        in: path
        required: true
        schema:
          type: string
      - name: permanent
        in: query
        schema:
          type: boolean
          default: false
      responses:
        '200':
          description: Version number of deleted schema
          content:
            application/json:
              schema:
                type: integer
        '404':
          description: Subject or version not found
  /subjects/{subject}/versions/{version}/schema:
    get:
      summary: Get raw schema by version
      operationId: getSchemaOnly
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: version
        in: path
        required: true
        schema:
          type: string
      responses:
        '200':
          description: Raw schema string
          content:
            application/json:
              schema:
                type: string
  /subjects/{subject}/versions/{version}/referencedby:
    get:
      summary: Get schemas that reference this schema
      operationId: getReferencedBy
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: version
        in: path
        required: true
        schema:
          type: string
      responses:
        '200':
          description: List of schema IDs referencing this version
          content:
            application/json:
              schema:
                type: array
                items:
                  type: integer
  /subjects/{subject}:
    post:
      summary: Check if schema is registered under subject
      operationId: lookUpSchemaUnderSubject
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: normalize
        in: query
        schema:
          type: boolean
          default: false
      - name: deleted
        in: query
        schema:
          type: boolean
          default: false
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RegisterSchemaRequest'
      responses:
        '200':
          description: Schema found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Schema'
        '404':
          description: Schema not found
    delete:
      summary: Delete subject and all versions
      operationId: deleteSubject
      tags:
      - Subjects
      parameters:
      - name: subject
        in: path
        required: true
        schema:
          type: string
      - name: permanent
        in: query
        schema:
          type: boolean
          default: false
      responses:
        '200':
          description: List of deleted version numbers
          content:
            application/json:
              schema:
                type: array
                items:
                  type: integer
components:
  schemas:
    ErrorMessage:
      type: object
      properties:
        error_code:
          type: integer
        message:
          type: string
    RegisterSchemaRequest:
      type: object
      required:
      - schema
      properties:
        schema:
          type: string
          description: The schema string
        schemaType:
          type: string
          enum:
          - AVRO
          - JSON
          - PROTOBUF
          default: AVRO
          description: The schema type
        references:
          type: array
          description: References to other schemas
          items:
            type: object
            properties:
              name:
                type: string
              subject:
                type: string
              version:
                type: integer
    Schema:
      type: object
      properties:
        subject:
          type: string
        id:
          type: integer
          description: Globally unique schema ID
        version:
          type: integer
        schemaType:
          type: string
          enum:
          - AVRO
          - JSON
          - PROTOBUF
        schema:
          type: string
          description: The schema definition string
        references:
          type: array
          items:
            type: object
            properties:
              name:
                type: string
              subject:
                type: string
              version:
                type: integer