Implementing Custom Policies With MuleSoft

Introduction

MuleSoft provides out-of-box policies that can be applied to APIs for enhancing the functionalities of the APIs. These policies include various categories like security, compliance, troubleshooting, transformation, QoS, custom, etc.

MuleSoft also provides the capabilities to implement custom policies and Custom Policies are policies that anyone can develop and apply to their APIs, with the intention of extending existing functionality or defining new ones. 

We need to perform a few steps for implementing the Custom policies.

• Develop the policy
• Package the policy
• Upload the resulting policy assets to Exchange
• Apply the policy to any API through API Manager

Setting Up a Project With the Archetype 

The first step to develop a custom policy consists of setting up a project with the required files. The easiest way to gather all your required files is by using the maven archetype. One way to do so is by configuring Maven’s settings.xml with the following section: 

x

<?xml version="1.0" encoding="UTF-8"?>

<profiles>

   <profile>

      <id>archetype-repository</id>

      <repositories>

         <repository>

            <id>archetype</id>

            <name>Mule Repository</name>

            <url>https://repositorymaster.mulesoft.org/nexus/content/repositories/public</url>

            <releases>

               <enabled>true</enabled>

               <checksumPolicy>fail</checksumPolicy>

            </releases>

            <snapshots>

               <enabled>true</enabled>

               <checksumPolicy>warn</checksumPolicy>

            </snapshots>

         </repository>

      </repositories>

   </profile>

</profiles>

Setting up a Project With the Archetype

Once maven profile has been setup, you can execute the following command:

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mvn -Parchetype-repository archetype:generate \ -DarchetypeGroupId=org.mule.tools \ -DarchetypeArtifactId=apigateway-custom-policy-archetype \ -DarchetypeVersion=1.2.0 \ -DgroupId=${orgId} \ -DartifactId=${policyName} \ -

Dversion=1.0.0-SNAPSHOT \ -Dpackage=mule-policy

These are the four files needed for having a working policy.

Here is the list of the videos explaining how to create custom policies and applied to API

Anypoint Custom Policies - Part I | MuleSoft

Anypoint Custom Policies - Part II | MuleSoft

Anypoint Custom Policies - Part III | MuleSoft

HTTP Policy Transform Extension

HTTP Policy Transform Extension is maven plugin and very useful when it comes to modifying the request and response that go through different policies.

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<dependency>

      <groupId>com.mulesoft.anypoint</groupId>

      <artifactId>mule-http-policy-transform-extension</artifactId>

      <version>${httpPolicyTransformVersion}</version>

      <classifier>mule-plugin</classifier>

      <exclusions>

          <exclusion>

              <groupId>org.mule.connectors</groupId>

              <artifactId>mule-http-connector</artifactId>

          </exclusion>

      </exclusions>

  </dependency>

Various list of the operation perform by HTTP Policy Transform Extension.

• Add and Remove request header or list of request headers.
• Add and Remove response header or list of response headers.
• Modify the request.
• Modify the response.

One of the use case where we can use this extension when we want encrypt or decrypt any field in request or response.

Note:  To use this extension, you need to have MuleSoft enterprise nexus repository credentials.

Code: https://github.com/Jitendra85/MuleSoft-Custom-Policies.git

Now you know how to implement Custom Policies with MuleSoft.