Authentication Reference

Client access to upstream API services is typically controlled by the application and configuration of Kong authentication plugins.

Generic authentication

The most common scenario is to require authentication and to not allow access for any unauthenticated request. To achieve this any of the authentication plugins can be used. The generic scheme/flow of those plugins works as follows:

  1. Apply an auth plugin to an api, or globally (you cannot apply one on consumers)
  2. Create a consumer entity
  3. Provide the consumer with authentication credentials for the specific authentication method
  4. Now whenever a request comes in Kong will check the provided credentials (depends on the auth type) and it will either block the request if it cannot validate, or add consumer and credential details in the headers and forward the request

The generic flow above does not always apply, for example when using external authentication like LDAP, then there is no consumer to be identified, and only the credentials will be added in the forwarded headers.

The authentication method specific elements and examples can be found in each plugin's documentation.

Consumers

The easiest way to think about consumers is to map them one-on-one to users. Yet, to Kong this does not matter. The core principle for consumers is that you can attach plugins to them, and hence customize request behaviour. So you might have mobile apps, and define one consumer for each app, or version of it. Or have a consumer per platform, e.g. an android consumer, an iOS consumer, etc.

It is an opaque concept to Kong and hence they are called "consumers" and not "users".

Anonymous Access

Prior to Kong 0.10.x, a given API could be configured to allow only authenticated access (by applying an auth plugin) or only anonymous access - it was not possible to have a given API allow some users to be authenticated and others to access anonymously.

Kong 0.10.x adds the ability to configure a given API to allow both authenticated and anonymous access. You might use this configuration to grant access to anonymous users with a low rate-limit, and grant access to authenticated users with a higher rate limit.

To configure an API like this, you first apply your selected authentication plugin, then create a new consumer to represent annonymous users, then configure your authentication plugin to allow anonymous access. Here is an example, which assumes you have already configured an API named example-api:

  1. Create an example API

    Issue the following cURL request to create example-api which will use the mockbin service to echo the request:

    $ curl -i -X POST \
      --url http://localhost:8001/apis/ \
      --data 'name=example-api' \
      --data 'uris=/auth-sample' \
      --data 'upstream_url=http://mockbin.org/request' 
    

    The url http://localhost:8000/auth-sample will now echo whatever is being requested.

  2. Configure the key-auth plugin for your API

    Issue the following cURL request on the API named example-api:

    $ curl -i -X POST \
      --url http://localhost:8001/apis/example-api/plugins/ \
      --data 'name=key-auth'
    

    Be sure to note the id - you'll need it in step 5.

  3. Verify that the key-auth plugin is properly configured

    Issue the following cURL request to verify that the key-auth plugin was properly configured on the API:

    $ curl -i -X GET \
      --url http://localhost:8000/auth-example
    

    Since you did not specify the required apikey header or parameter, and you have not yet enabled anonymous access, the response should be 403 Forbidden:

    HTTP/1.1 403 Forbidden
    ...
    
    {
      "message": "No API key found in headers or querystring"
    }
    
  4. Create an anonymous consumer

    Every request proxied by Kong must be associated with a consumer. You'll now create a consumer named anonymous_users (that Kong will utilize when proxying anonymous access) by issuing the following request:

    $ curl -i -X POST \
      --url http://localhost:8001/consumers/ \
      --data "username=anonymous_users"
    

    You should see a response similar to the one below:

    HTTP/1.1 201 Created
    Content-Type: application/json
    Connection: keep-alive
    
    {
      "username": "anonymous_users",
      "created_at": 1428555626000,
      "id": "bbdf1c48-19dc-4ab7-cae0-ff4f59d87dc9"
    }
    

    Be sure to note the id - you'll need it in the next step.

  5. Enable anonymous access

    You'll now re-configure the key-auth plugin to permit anonymous access by issuing the following request (replace the sample uuids below by the id values from step 2 and 4):

    $ curl -i -X PATCH \
      --url http://localhost:8001/apis/example-api/plugins/4a223b63-c44a-40e5-9102-b23335f594ca \
      --data "config.anonymous=bbdf1c48-19dc-4ab7-cae0-ff4f59d87dc9"
    

    The config.anonymous=<consumer uuid> parameter instructs the key-auth plugin on this API to permit anonymous access, and to associate such access with the consumer id we received in the previous step. It is required that you provide a valid and pre-existing consumer id in this step - validity of the consumer id is not currently checked when configuring anonymous access, and provisioninf of a consumer id that doesn't already exist will result in an incorrect configuration.

  6. Check anonymous access

    Confirm that your API now permits anonymous access by issuing the following request:

    $ curl -i -X GET \
      --url http://localhost:8000/auth-sample
    

    This is the same request you made in step #3, however this time the request should succeed, because you enabled anonymous access in step #5.

    The response (which is the request as Mockbin received it) should have these elements:

    {
      ...
      "headers": {
        ...
        "x-consumer-id": "713c592c-38b8-4f5b-976f-1bd2b8069494",
        "x-consumer-username": "anonymous_users",
        "x-anonymous-consumer": "true",
        ...
      },
      ...
    }
    

    It shows the request was succesful, but anonymous.

Multiple Authentication

Kong 0.10.x extends the ability to apply multiple authentication plugins for a given API, allowing different clients to utilize different authentication methods to access a given API endpoint.

The behaviour of the auth plugins can be set to do either a logical AND, or a logical OR when evaluating multiple authentication credentials. The key to the behaviour is the config.anonymous property.

  • config.anonymous not set
    If this property is not set (empty) then the auth plugins will always perform authentication and return a 40x response if not validated. This results in a logical AND when multiple auth plugins are being invoked.
  • config.anonymous set to a valid consumer id
    In this case the auth plugin will only perform authentication if it was not already authenticated. When authentication fails, it will not return a 40x response, but set anonymous consumer as the consumer. This results in a logical OR + 'anonymous access' when multiple auth plugins are being invoked.

NOTE 1: Either all or none of the auth plugins must be configured for anonymous access. The behaviour is undefined if they are mixed.

NOTE 2: When using the AND method, the last plugin executed will be the one setting the credentials passed to the upstream service. With the OR method, it will be the first plugin that succesfully authenticates the consumer, or the last plugin that will set its configured anonymous consumer.

NOTE 3: When using the OAuth2 plugin in an AND fashion, then also the OAuth2 endpoints for requesting tokens etc. will require authentication by the other configured auth plugins.

When multiple authentication plugins are enabled in an `OR` fashion on a given API, and it is desired that anonymous access be forbidden, the upstream service MUST be configured to reject requests in which the `X-Anonymous-Consumer` header is set to `true`. Failure to do so will allow unauthorized requests.

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