Authentication Reference

Traffic to your Upstream services (APIs or microservices) is typically controlled by the application and configuration of various Kong authentication plugins. Because Kong’s Service entity represents a 1-to-1 mapping of your own upstream services, the simplest scenario is to configure authentication plugins on the Services of your choosing.

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:

Apply an auth plugin to a Service, or globally (you cannot apply one on consumers)
Create a consumer entity
Provide the consumer with authentication credentials for the specific authentication method
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 behavior. 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

Kong has the ability to configure a given Service 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 a Service like this, you first apply your selected authentication plugin, then create a new consumer to represent anonymous users, then configure your authentication plugin to allow anonymous access. Here is an example, which assumes you have already configured a Service named example-service and the corresponding Route:

Create an example Service and a Route

Issue the following cURL request to create example-service pointing to httpbin.konghq.com, which will echo the request:

 curl -i -X POST \
   --url http://localhost:8001/services/ \
   --data 'name=example-service' \
   --data 'url=https://httpbin.konghq.com/anything'

Add a Route to the Service:

 curl -i -X POST \
   --url http://localhost:8001/services/example-service/routes \
   --data 'paths[]=/auth-sample'

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

Configure the key-auth Plugin for your Service

Issue the following cURL request to add a plugin to a Service:
```
 curl -i -X POST \
   --url http://localhost:8001/services/example-service/plugins/ \
   --data 'name=key-auth'
```
Be sure to note the created Plugin id - you’ll need it in step 5.
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 Service:
```
 curl -i -X GET \
   --url http://localhost:8000/auth-sample
```
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"
 }
```
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 use 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 Consumer id - you’ll need it in the next step.
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/plugins/<your-plugin-id> \
   --data "config.anonymous=<your-consumer-id>"
```
The config.anonymous=<your-consumer-id> parameter instructs the key-auth plugin on this Service 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 provisioning of a Consumer id that doesn’t already exist will result in an incorrect configuration.
Check anonymous access

Confirm that your Service 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 httpbin 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 successful, but anonymous.

Multiple Authentication

Kong supports multiple authentication plugins for a given Service, allowing different clients to use different authentication methods to access a given Service or Route.

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 the 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 successfully 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 and so forth will require authentication by the other configured auth plugins.

When multiple authentication plugins are enabled in an OR fashion on a given service, and you want anonymous access to be forbidden, then the Request Termination plugin should be configured on the anonymous consumer. Failure to do so will allow unauthorized requests.