Add Key Authentication (also referred to as an API key) to your APIs. Consumers then add their key either in a querystring parameter or a header to authenticate their requests.


Terminology

  • api: your upstream service placed behind Kong, for which Kong proxies requests to.
  • plugin: a plugin executing actions inside Kong before or after a request has been proxied to the upstream API.
  • consumer: a developer or service using the api. When using Kong, a Consumer only communicates with Kong which proxies every call to the said, upstream api.
  • credential: in the key-auth plugin context, a unique string associated with a consumer, also referred to as an API key.

Configuration

Configuring the plugin is straightforward, you can add it on top of an API by executing the following request on your Kong server:

$ curl -X POST http://kong:8001/apis/{api}/plugins \
    --data "name=key-auth" \
    --data "config.hide_credentials=true"

api: The id or name of the API that this plugin configuration will target

You can also apply it for every API using the http://kong:8001/plugins/ endpoint. Read the Plugin Reference for more information.

Once applied, any user with a valid credential can access the service/API. To restrict usage to only some of the authenticated users, also add the ACL plugin (not covered here) and create whitelist or blacklist groups of users.

form parameter default description
name The name of the plugin to use, in this case: key-auth.
config.key_names
optional
apikey Describes an array of comma separated parameter names where the plugin will look for a key. The client must send the authentication key in one of those key names, and the plugin will try to read the credential from a header or the querystring parameter with the same name.
note: the key names may only contain [a-z], [A-Z], [0-9] and [-].
config.key_in_body false If enabled, the plugin will read the request body (if said request has one and its MIME type is supported) and try to find the key in it. Supported MIME types are application/www-form-urlencoded, application/json, and multipart/form-data.
config.hide_credentials
optional
false An optional boolean value telling the plugin to hide the credential to the upstream API server. It will be removed by Kong before proxying the request.
config.anonymous
optional
`` An optional string (consumer uuid) value to use as an "anonymous" consumer if authentication fails. If empty (default), the request will fail with an authentication failure 4xx

Usage

In order to use the plugin, you first need to create a Consumer to associate one or more credentials to. The Consumer represents a developer using the final service/API.

Create a Consumer

You need to associate a credential to an existing Consumer object, that represents a user consuming the API. To create a Consumer you can execute the following request:

$ curl -X POST http://kong:8001/consumers/ \
    --data "username=<USERNAME>" \
    --data "custom_id=<CUSTOM_ID>"
HTTP/1.1 201 Created

{
    "username":"<USERNAME>",
    "custom_id": "<CUSTOM_ID>",
    "created_at": 1472604384000,
    "id": "7f853474-7b70-439d-ad59-2481a0a9a904"
}
parameter default description
username
semi-optional
The username of the Consumer. Either this field or custom_id must be specified.
custom_id
semi-optional
A custom identifier used to map the Consumer to another database. Either this field or username must be specified.

A Consumer can have many credentials.

If you are also using the ACL plugin and whitelists with this service, you must add the new consumer to a whitelisted group. See ACL: Associating Consumers for details.

Create an API Key

You can provision new credentials by making the following HTTP request:

$ curl -X POST http://kong:8001/consumers/{consumer}/key-auth -d ''
HTTP/1.1 201 Created

{
    "consumer_id": "876bf719-8f18-4ce5-cc9f-5b5af6c36007",
    "created_at": 1443371053000,
    "id": "62a7d3b7-b995-49f9-c9c8-bac4d781fb59",
    "key": "62eb165c070a41d5c1b58d9d3d725ca1"
}

consumer: The id or username property of the Consumer entity to associate the credentials to.

form parameter default description
key
optional
You can optionally set your own unique key to authenticate the client. If missing, the plugin will generate one.
Note: It is recommended to let Kong auto-generate the key. Only specify it yourself if you are migrating an existing system to Kong. You must re-use your keys to make the migration to Kong transparent to your Consumers.

Using the API Key

Simply make a request with the key as a querystring parameter:

$ curl http://kong:8000/{api path}?apikey=<some_key>

Or in a header:

$ curl http://kong:8000/{api path} \
    -H 'apikey: <some_key>'

Upstream Headers

When a client has been authenticated, the plugin will append some headers to the request before proxying it to the upstream API/Microservice, so that you can identify the Consumer in your code:

  • X-Consumer-ID, the ID of the Consumer on Kong
  • X-Consumer-Custom-ID, the custom_id of the Consumer (if set)
  • X-Consumer-Username, the username of the Consumer (if set)
  • X-Credential-Username, the username of the Credential (only if the consumer is not the 'anonymous' consumer)
  • X-Anonymous-Consumer, will be set to true when authentication failed, and the 'anonymous' consumer was set instead.

You can use this information on your side to implement additional logic. You can use the X-Consumer-ID value to query the Kong Admin API and retrieve more information about the Consumer.

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