/openapi-oathkeeper

openapi-oathkeeper is a CLI for generating Ory Oathkeeper rules from an OpenAPI 3 contract and save a lot of time and effort, especially for larger projects with many endpoints or many services.

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Ory Oathkeeper rules from OpenAPI

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This CLI generates secure and consistent OathKeeper rules that enforce authentication and authorization policies for each API endpoint from an OpenAPI contrat.

This project automate the generation of Ory Oathkeeper rules from an OpenAPI contract and save a lot of time especially for larger projects with many endpoints or many services by using the existing documentation provided in an OpenAPI contract. This can improve the overall security of the API and ensure that access is granted only to authorized parties. Additionally, this tool can simplify the development process by reducing the amount of manual work required to write and maintain OathKeeper rules.

Ory Oathkeeper

If you're not yet familiar with Ory Oathkeeper, Oathkeeper is an Identity & Access Proxy (IAP) and Access Control Decision API that authorizes HTTP requests based on sets of Access Rules. You can find more information and get started with Ory Oathkeeper.

An Identity & Access Proxy is typically deployed in front of (think API Gateway or Service mesh) web-facing applications and is capable of authenticating and optionally authorizing access requests. The Access Control Decision API can be deployed alongside an existing API Gateway or reverse proxy.

Get Started

To use this tool, follow the bellow instructions:

  1. First you have to download the binary from the latest release.
  2. Provides the path to your OpenAPI contract file.
./openapi-oathkeeper generate -f ./openapi.json

Once you have specified these options, the tool will analyze your contract and generate OathKeeper rules that enforce the specified access policies. You can then save these rules to a file to make it read by Oathkeeper.

Here is an example Oathkeeper rules output from the Petstore OpenAPI

Oathkeeper rules output
[
    {
        "id": "addPet",
        "version": "",
        "description": "Add a new pet to the store",
        "match": {
            "methods": [
                "POST"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "createUser",
        "version": "",
        "description": "This can only be done by the logged in user.",
        "match": {
            "methods": [
                "POST"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "createUsersWithListInput",
        "version": "",
        "description": "Creates list of users with given input array",
        "match": {
            "methods": [
                "POST"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user/createWithList"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "deleteOrder",
        "version": "",
        "description": "For valid response try integer IDs with value < 1000. Anything above 1000 or nonintegers will generate API errors",
        "match": {
            "methods": [
                "DELETE"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/store/order/<\\d+>"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "deletePet",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "DELETE"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet/<\\d+>"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "deleteUser",
        "version": "",
        "description": "This can only be done by the logged in user.",
        "match": {
            "methods": [
                "DELETE"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user/<.+>"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "findPetsByStatus",
        "version": "",
        "description": "Multiple status values can be provided with comma separated strings",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet/findByStatus"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "findPetsByTags",
        "version": "",
        "description": "Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet/findByTags"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "getInventory",
        "version": "",
        "description": "Returns a map of status codes to quantities",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/store/inventory"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "getOrderById",
        "version": "",
        "description": "For valid response try integer IDs with value <= 5 or > 10. Other values will generate exceptions.",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/store/order/<\\d+>"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "getPetById",
        "version": "",
        "description": "Returns a single pet",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet/<\\d+>"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "getUserByName",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user/<.+>"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "loginUser",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user/login"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "logoutUser",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user/logout"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "placeOrder",
        "version": "",
        "description": "Place a new order in the store",
        "match": {
            "methods": [
                "POST"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/store/order"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "updatePet",
        "version": "",
        "description": "Update an existing pet by Id",
        "match": {
            "methods": [
                "PUT"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "updatePetWithForm",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "POST"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet/<\\d+>"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "updateUser",
        "version": "",
        "description": "This can only be done by the logged in user.",
        "match": {
            "methods": [
                "PUT"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/user/<.+>"
        },
        "authenticators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "uploadFile",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "POST"
            ],
            "url": "<(https://cerberauth\\.com/api/v3|http://swagger\\.io/api/v3)>/pet/<\\d+>/uploadImage"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "required_scope": [
                        "write:pets",
                        "read:pets"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": null,
        "errors": null,
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    }
]

Configuration

As the authenticator rule may require additional information in order to make authorization and authentication working properly, additional information can be passed either by OpenAPI Extensions or configuration file.

Configuration File

The recommended approach involves using dedicated configuration files for your Oathkeeper rules. These configuration files provide a more flexible and user-friendly way of managing your security settings.

Every Oathkeeper rule property can be configured this way. Here are the available properties:

Field Type Key
Prefix string "prefix"
ServerUrls []string "server_urls"
Upstream Upstream "upstream"
Authenticators Map of Authenticators "authenticators"
Authorizer Authorization Handler "authorizer"
Mutators Array of Mutator Handlers "mutators"
Errors Array of Error Handlers "errors"

Below is an example of a configuration file in YAML format:

prefix: cerberauth

server_urls:
  - https://www.cerberauth.com/api
  - https://api.cerberauth.com/api

authenticators:
  openidconnect:
    handler: "jwt"
    config:
      target_audience:
      - https://api.cerberauth.com

In order to generate rules using the CLI, simply run the command in your terminal with the appropriate arguments.

./openapi-oathkeeper generate -c ./test/config/sample.yaml -f ./test/stub/sample.openapi.json
Oathkeeper rules output
[
    {
        "id": "cerberauth:getUserById",
        "version": "",
        "description": "",
        "match": {
            "methods": [
                "GET"
            ],
            "url": "<^(https://www\\.cerberauth\\.com/api|https://api\\.cerberauth\\.com/api)(/users/(?:[[:alnum:]]?\\x2D?=?\\??&?_?)+/?)$>"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "jwks_urls": [
                        "https://console.ory.sh/.well-known/jwks.json"
                    ],
                    "required_scope": [
                        "user:read"
                    ],
                    "target_audience": [
                        "https://api.cerberauth.com"
                    ],
                    "trusted_issuers": [
                        "https://console.ory.sh"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "errors": [
            {
                "handler": "json",
                "config": null
            }
        ],
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    },
    {
        "id": "cerberauth:updateUser",
        "version": "",
        "description": "This can only be done by the logged in user.",
        "match": {
            "methods": [
                "PUT"
            ],
            "url": "<^(https://www\\.cerberauth\\.com/api|https://api\\.cerberauth\\.com/api)(/users/(?:[[:alnum:]]?\\x2D?=?\\??&?_?)+/?)$>"
        },
        "authenticators": [
            {
                "handler": "jwt",
                "config": {
                    "jwks_urls": [
                        "https://console.ory.sh/.well-known/jwks.json"
                    ],
                    "required_scope": [
                        "user:write"
                    ],
                    "target_audience": [
                        "https://api.cerberauth.com"
                    ],
                    "trusted_issuers": [
                        "https://console.ory.sh"
                    ]
                }
            }
        ],
        "authorizer": {
            "handler": "allow",
            "config": null
        },
        "mutators": [
            {
                "handler": "noop",
                "config": null
            }
        ],
        "errors": [
            {
                "handler": "json",
                "config": null
            }
        ],
        "upstream": {
            "preserve_host": false,
            "strip_path": "",
            "url": ""
        }
    }
]

OpenAPI Extension

OpenAPI Extensions serve as an extension mechanism for the OpenAPI Specification (OAS). When using OpenAPI-Oathkeeper with OpenAPI Extensions, you can embed Oathkeeper-specific rules directly within your API documentation. This integration can be beneficial when you desire a unified source of truth for both API specifications and security rules.

Here the available configurations:

Name Security Schemes OpenAPI Extension Name
JWKS URI oauth2, http x-authenticator-jwks-uri
Issuer oauth2, http x-authenticator-issuer
Audience openIdConnect, oauth2, http x-authenticator-audience

Example

Here's an example of the same OpenAPI contract but in JSON format

OpenAPI example using OpenAPI Extensions
{
    "openapi": "3.0.0",
    "info": {
        "title": "My API",
        "version": "1.0.0"
    },
    "servers": [
        {
            "url": "https://api.example.com",
            "description": "Production server"
        }
    ],
    "paths": {
        "/users/{id}": {
            "get": {
                "summary": "Get user by ID",
                "operationId": "getUserById",
                "parameters": [
                    {
                        "name": "id",
                        "in": "path",
                        "description": "The user id. ",
                        "required": true,
                        "schema": {
                            "type": "string"
                        }
                    }
                ],
                "responses": {
                    "200": {
                        "description": "Successful response",
                        "content": {
                            "application/json": {
                                "schema": {
                                    "type": "object",
                                    "properties": {
                                        "id": {
                                            "type": "integer"
                                        },
                                        "email": {
                                            "type": "string"
                                        }
                                    }
                                }
                            }
                        }
                    }
                },
                "security": [
                    {
                        "openidconnect": [
                            "user:read"
                        ]
                    }
                ]
            },
            "put": {
                "tags": [
                    "user"
                ],
                "summary": "Update user",
                "description": "This can only be done by the logged in user.",
                "operationId": "updateUser",
                "parameters": [
                    {
                        "name": "id",
                        "in": "path",
                        "description": "user id that need to be updated",
                        "required": true,
                        "schema": {
                            "type": "string"
                        }
                    }
                ],
                "requestBody": {
                    "description": "Update an existent user in the store",
                    "content": {
                        "application/json": {
                            "schema": {
                                "$ref": "#/components/schemas/User"
                            }
                        }
                    }
                },
                "responses": {
                    "default": {
                        "description": "successful operation"
                    }
                },
                "security": [
                    {
                        "openidconnect": [
                            "user:write"
                        ]
                    }
                ]
            }
        }
    },
    "components": {
        "schemas": {
            "User": {
                "type": "object",
                "properties": {
                    "id": {
                        "type": "integer",
                        "format": "int64",
                        "example": 10
                    },
                    "email": {
                        "type": "string",
                        "example": "john@email.com"
                    }
                }
            }
        },
        "securitySchemes": {
            "openidconnect": {
                "type": "openIdConnect",
                "openIdConnectUrl": "https://project.console.ory.sh/.well-known/openid-configuration"
            }
        }
    }
}

Command line documentation

The documentation is available as markdown files in the docs directory or by running openapi-oathkeeper help.

Roadmap

Please note that this tool is currently in beta stage and there may be limitations and bugs. Improvements and new features should come to make it more powerful and useful for developers. Any feedback or suggestions are greatly appreciated!

You can find the milestones and future enhancements planned for this tool on the project's GitHub milestones page.

Useful Links

License

MIT © CerberAuth