Certificate-Based Authentication With the Microsoft Graph API in MuleSoft
This article will demonstrate how to get an access token while using Microsoft Graph via certificate based authentication in MuleSoft. This is used to access Microsoft Graph API(s) for SharePoint operations, drive operations, etc. As there were no out-of-the-box solutions available for the OAuth client credential authentication using certificate, I have come up with a solution of my own.
Before we begin, make sure you have set up your Microsoft Azure App and have gotten your certificate (further explanation can be found in Microsoft document). Below, I will cover MuleSoft implementation, assuming that you have the certificate “.pfx” file and the tenant and client ID from the Azure App.
The steps to get access token are:
- Create a JWT token from the .pfx certificate parameters: certificate thumbprint and the private key.
- Using the JWT Token you just created as a parameter, along with client ID and 3 other static parameters, you will get the bearer access token to access the Microsoft Graph API resources.
Please find the implementation steps below. Here is the git repo of the implementation to refer to and copy.
- To create the JWT token, we first extract the thumbprint and and private key from the certificate. I have written two method in Java to fetch the information. Pass the certificate and the password as input to the Java methods from DataWeave. Please find the CommonUtils.java here.
2. To create the JWT token, use the module from this DataWeave library.
3. Form the multipart payload, as shown below, to do a POST request to Graph API’s endpoint, /{tenant}/oauth2/v2.0/token, using the JWT token, Client ID, and the 3 static parameters.
4. After the HTTP request component, form the bearer access token from the Graph API response payload.
5. Take note of the project structure and the config details.
Please Note Additional Dependencies which are required in POM<dependency>
<groupId>68ef9520–24e9–4cf2-b2f5–620025690913</groupId><artifactId>data-weave-jwt-library</artifactId><version>1.0.0</version>
<classifier>dw-library</classifier>
</dependency><dependency>
<groupId>javax.xml.bind</groupId>
<artifactId>jaxb-api</artifactId>
<version>2.3.1</version>
</dependency>
6. Now, run and test the generate-access-token flow.
7. And voila, we received the access token!!
And that’s it. Have a great day.
