Set up SSOCookieProvider Federation Provider

How to configure the SSOCookieProvider.

The SSOCookieProvider enables the federation of the authentication event that occurred through KnoxSSO. KnoxSSO is a typical service provider-initiated webSSO mechanism that sets a cookie to be presented by browsers to participating applications and cryptographically verified.

Knox Gateway needs a pluggable mechanism for consuming these cookies and federating the KnoxSSO authentication event as an asserted identity in its interaction with the cluster for REST API invocations. This provider is useful when an application that is integrated with KnoxSSO for authentication also consumes REST APIs through the Knox Gateway.

Open the cluster topology descriptor file, $cluster-name.xml, in a text editor.
Add a SSOCookieProvider federation provider to topology/gateway as follows:
```
<provider>
        <role>federation</role>
        <name>SSOCookieProvider</name>
        <enabled>true</enabled>
        <param>
            <name>sso.authentication.provider.url</name>
            <value>https://host:port/gateway/idp/api/v1/websso</value>
        </param>
    </provider>
```
where the values of the parameters are specific to your environment:
- <name>sso.authentication.provider.url</name></value>https://host:port/gateway/idp/api/v1/websso</value>
- (Required) Indicates the location of the KnoxSSO endpoint and where to redirect the useragent when no SSO cookie is found in the incoming request.
Save the file.

<topology>
  <gateway>
    <provider>
        <role>federation</role>
        <name>SSOCookieProvider</name>
        <enabled>true</enabled>
        <param>
            <name>sso.authentication.provider.url</name>
            <value>https://localhost:9443/gateway/idp/api/v1/websso</value>
        </param>
    </provider>
    <provider>
        <role>identity-assertion</role>
        <name>Default</name>
        <enabled>true</enabled>
    </provider>
  </gateway>    
  <service>
      <role>WEBHDFS</role>
      <url>http://localhost:50070/webhdfs</url>
  </service>
  <service>
      <role>WEBHCAT</role>
      <url>http://localhost:50111/templeton</url>
  </service>
</topology>