Chapter 5. Transforming 3scale API Management message content using policy extensions in Fuse

Procedure

1. Write an Apache Camel application in Java using the Camel netty4-http component to implement the HTTP proxy. You can then use any Camel component to transform the message.

   The following simple example performs an uppercase transformation of the request and response from the service:

   import java.nio.file.Files;
   import java.nio.file.Path;
   import java.util.Locale;
   
   import org.apache.camel.Exchange;
   import org.apache.camel.Message;
   import org.apache.camel.builder.RouteBuilder;
   import org.apache.camel.model.RouteDefinition;
   
   public class ProxyRoute extends RouteBuilder {
   
       @Override
       public void configure() throws Exception {
           final RouteDefinition from;
           if (Files.exists(keystorePath())) {
               from = from("netty4-http:proxy://0.0.0.0:8443?ssl=true&keyStoreFile=/tls/keystore.jks&passphrase=changeit&trustStoreFile=/tls/keystore.jks"); 1
           } else {
               from = from("netty4-http:proxy://0.0.0.0:8080");
           }
   
           from
               .process(ProxyRoute::uppercase)
               .toD("netty4-http:"
                   + "${headers." + Exchange.HTTP_SCHEME + "}://" 2
                   + "${headers." + Exchange.HTTP_HOST + "}:"
                   + "${headers." + Exchange.HTTP_PORT + "}"
                   + "${headers." + Exchange.HTTP_PATH + "}")
               .process(ProxyRoute::uppercase);
       }
   
       Path keystorePath() {
           return Path.of("/tls", "keystore.jks");
       }
   
       public static void uppercase(final Exchange exchange) { 3
           final Message message = exchange.getIn();
           final String body = message.getBody(String.class);
           message.setBody(body.toUpperCase(Locale.US));
       }
   
   }

   1

   In this simple example, if your Java keystore file is mounted at /tls/keystore.jks, the listening port is set to 8443.

   2

   When the Camel proxy policy is invoked by 3scale, the values for the HTTP_SCHEME, HTTP_HOST, HTTP_PORT, and HTTP_PATH headers are automatically set based on the values configured for the backend API in 3scale.

   3

   This simple example converts the message content to uppercase. You can perform more complex transformations on request and response message content, for example, XML to JSON, using Camel Enterprise Integration Patterns.

2. Deploy your Camel application on OpenShift and expose it as a service. For more details, see Creating and Deploying Applications on Fuse on OpenShift.

Procedure

1. In the 3scale Admin Portal, select Integration > Policies.
2. Select POLICIES > Add policy > Camel Service.

3. Enter the OpenShift routes used to connect to the Camel HTTP proxy service in the appropriate fields:

   • https_proxy: Connect to the Camel HTTP proxy using the http protocol and TLS port, for example:

     http://camel-proxy.my-3scale-management-project.svc:8443

   • http_proxy: Connect to the Camel HTTP proxy using the http protocol and port, for example:

     http://camel-proxy.my-3scale-management-project.svc:8080

   • all_proxy: Connect to the Camel HTTP proxy using the http protocol and port when the protocol is not specified, for example:

     http://camel-proxy.my-3scale-management-project.svc:8080

4. Promote the updated policy configuration to your staging or production environment. For example, click Promote v. 3 to Staging APIcast.

5. Test the APIcast policy configuration using a 3scale curl command, for example:

   curl "https://testapi-3scale-apicast-staging.myuser.app.dev.3sca.net:443/?user_key=MY_USER_KEY" -k

   APIcast establishes a new TLS session for the connection to the Camel HTTP proxy.

6. Confirm that the message content has been transformed, which in this example means converted to uppercase.

7. If you wish to bypass APIcast and test the Camel HTTP proxy directly using TLS, you must use a custom HTTP client. For example, you can use the netcat command:

   $ print "GET https://mybackend.example.com HTTP/1.1\nHost: mybackend.example.com\nAccept: */*\n\n" | ncat --no-shutdown --ssl my-camel-proxy 8443

   This example creates an HTTP proxy request using the full URL after GET, and uses the ncat --ssl parameter to specify a TLS connection to the my-camel-proxy host on port 8443.

   Note

   You cannot use curl or other common HTTP clients to test the Camel HTTP proxy directly because the proxy does not support HTTP tunneling using the CONNECT method. When using HTTP tunneling with CONNECT, the transport is end-to-end encrypted, which does not allow the Camel HTTP proxy to mediate the payload.