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Define authentication policies on the Ingress Citrix ADC¶

Authentication policies are used to enforce access restrictions to the resources hosted by an application or API server.

Citrix provides a Kubernetes CustomResourceDefinitions (CRDs) called the Auth CRDthat you can use with the Citrix ingress controller to define authentication policies on the ingress Citrix ADC.

Auth CRD definition¶

The Auth CRD is available in the Citrix ingress controller GitHub repo at: auth-crd.yaml. The Auth CRD provides attributes for various options that are required to define the authentication policies on the Ingress Citrix ADC.

The following is the Auth CRD definition:

apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
  name: authpolicies.citrix.com
spec:
  group: citrix.com
  version: v1beta1
  names:
    kind: authpolicy
    plural: authpolicies
    singular: authpolicy
  scope: Namespaced
  validation:
    openAPIV3Schema:
      properties:
        spec:
          properties:
            servicenames:
              description: 'Name of the services that needs to be binded to rewrite policy.'
              type: array
              items:
                type: string
                maxLength: 127
            auth_providers:
              description: 'Auth Config for required auth providers, one or more of these can be created'
              type: array
              items:
                  description: " create config for a single auth provider of a particular type"
                  properties:
                    name:
                      description: 'Name for this provider, has to be unique, referenced by auth policies'
                      type: string

                    oauth:
                      description: 'Auth provided by external oAuth provider' 
                      properties:
                          issuer:
                              description: 'Identity of the server whose tokens are to be accepted'
                              type: string
                          jwks_uri:
                              description: 'URL of the endpoint that contains JWKs (Json Web Key) for JWT (Json Web Token) verification'
                              type: string
                          audience:
                              description: 'Audience for which token sent by Authorization server is applicable'
                              type: array
                              items:
                                type: string
                          token_in_hdr:
                              description: 'custom header name where token is present, default is Authorization header'
                              type: array
                              items:
                                type: string
                          token_in_param:
                              description: 'query parameter name where token is present'
                              type: array
                              items:
                                type: string

                    basic_local_db:
                      description: 'Basic HTTP authentication, user data in local DB'

                  required:
                    - name

            auth_policies:
              description: "Auth policies"
              type: array
              items:
                description: "Auth policy"
                properties:
                  resource:
                      description: " endpoint/resource selection criteria"
                      properties:
                        path:
                          description: "api resource path e.g. /products. "
                          type: array
                          items:
                            type: string
                        method:
                          type: array
                          items:
                            type: string
                            enum: ['GET', 'PUT', 'POST','DELETE']
                      required:
                        - path
                  provider:
                    description: "name of the auth provider for the policy, empty if no authentication required"
                    type: array
                    items:
                      type: string
                required:
                  - resource
                  - provider

          required:
            - servicenames

Auth CRD attributes¶

The Auth CRD provides the following attributes that you use to define the authentication policies:

servicenames
auth_providers
auth_policies

servicenames¶

The name of the services that you want to bind to the authentication policy.

auth_providers¶

The providers define the authentication mechanism and parameters that are required for the authentication mechanism. The CRD supports both basic authentication and OAuth authentication.

Basic authentication¶

To use basic authentication, you must create the user accounts on the ingress Citrix ADC. Any new request to the services in your Kubernetes deployment must contain the Authentication header with the user name and password and the request is validated with user credentials within the Citrix ADC.

Basic authentication attributes¶

The following are the attributes for basic authentication:

Attribute	Description
`name`	The name of the provider. This name is used in the policies to refer the provider.
`basic_local_db`	Specifies that local authentication is used with the HTTP basic authentication scheme. The requests should contain the authentication header with user name and password.

OAuth authentication¶

The OAuth authentication mechanism, requires an external identity provider to authenticate the client using oAuth2 and issue an Access token. When the client presents the Access token to Citrix ADC as an access credential, the Citrix ADC validates the token using the configured values. If the token validation is successful then Citrix ADC grants access to the client.

OAuth authentication attributes¶

The following are the attributes for OAuth authentication:

Attribute	Description
`Issuer`	The identity (usually a URL) of the server whose tokens need to be accepted for authentication.
`jwks_uri`	The URL of the endpoint that contains JWKs (JSON Web Key) for JWT (JSON Web Token) verification.
`audience`	The identity of the service or application for which the token is applicable.
`token_in_hdr`	The custom header name where the token is present. Default is `Authorization` header. Note: You can specify more than one header.
`token_in_param`	The query parameter where the token is present.

auth_policies¶

The policies allow you to define the traffic selection criteria to apply the authentication mechanism and also to specify the provider that you want to use for the selected traffic.

The following are the attributes for policies:

Attribute	Description
`path`	An array of URL path prefixes that refer to a specific API endpoint. For example, `/api/v1/products/`.
`method`	An array of HTTP methods. Allowed values are GET, PUT, POST, or DELETE. Note: The traffic is selected if the incoming request URI matches with any of the paths AND any of the listed methods. If the method is not specified then the path alone is used for the traffic selection criteria.
`provider`	Specifies the authentication mechanism that needs to be used. If no value is provided then authentication is not performed.

Deploy the Auth CRD¶

Perform the following to deploy the Auth CRD:

Download the CRD (auth-crd.yaml).

Deploy the Auth CRD using the following command:

kubectl create -f auth-crd.yaml

For example,

root@master:~# kubectl create -f auth-crd.yaml

customresourcedefinition.apiextensions.k8s.io/authpolicies.citrix.com created

How to write the authentication policies¶

After you have deployed the CRD provided by Citrix in the Kubernetes cluster, you can define the authentication policy configuration in a .yaml file. In the .yaml file, use authpolicy in the kind field and in the spec section add the Auth CRD attributes based on your requirement for the policy configuration.

After you deploy the .yaml file, the Citrix ingress controller applies the authentication policy configuration on the Ingress Citrix ADC device.

The following is sample authentication policy definition (auth_example1.yaml):

apiVersion: citrix.com/v1beta1
kind: authpolicy
metadata:
  name: authexample
spec:
    servicenames:
    - frontend

    auth_providers:

        - name: "local-auth-provider"
          basic-local-db:

        - name: "jwt-auth-provider"
          oauth:
            issuer: "https://sts.windows.net/tenant1/"
            jwks_uri: "https://login.microsoftonline.com/tenant1/discovery/v2.0/keys"
            audience : ["https://vault.azure.net"]

    auth_policies:

        - resource:
            path:
              - '/orders/'
              - '/shipping/'
            method: [GET, POST]
          provider: ["local-auth-provider"]

        - resource:
            path:
              - '/products/'
            method: [POST]
          provider: ["local-auth-provider"]

          # no auth for this
        - resource:
            path:
              - '/products/'
            method: [GET]
          provider: []

          # oauth provider for this
        - resource:
            path:
              -  '/reviews/'
          provider: ["jwt-auth-provider"]

The sample authentication policy performs the following:

The Citrix ADC performs the authentication mechanism specified in the provider local-auth-provider on the requests to the following endpoints:
- orders, shipping, and GET or POST
- products and POST
The Citrix ADC does not perform the authentication for the products and GET endpoints.

The Citrix ADC performs the authentication mechanism specified in the provider jwt-auth-provider on the requests to the reviews endpoint. If the token is present in a custom header, it can be specified using the token_in_hdr attribute as follows:

  oauth:
    issuer: "https://sts.windows.net/tenant1/"
    jwks_uri: "https://login.microsoftonline.com/tenant1/discovery/v2.0/keys"
    audience : ["https://vault.azure.net"]
    token_in_hdr : [“custom-hdr1”]

Similarly, if the token is present in a query parameter, it can be specified using the “token_in_param” attribute as follows:

  oauth:
    issuer: "https://sts.windows.net/tenant1/"
    jwks_uri: "https://login.microsoftonline.com/tenant1/discovery/v2.0/keys"
    audience : ["https://vault.azure.net"]
    token_in_param : [“query-param1”]