Handle OAuth Authentication using API Gateway Pre-request Configuration

In this article, we will explain how to set up a Pre-request to retrieve an OAuth 2.0 access token for connecting to an API using an API Gateway.

OptiSigns API Gateway allows for OAuth authentication via Pre-request. This gives users the capability to consume API that requires OAuth authentication or similar.

To get started, you'll need to set up an API request. Hover over Account Name → More → Click DataSources:

From there, hit Add Request.

Create a GET Request and input your API endpoint, then click Pre-request:

Within the Pre-request field, input the following code:

const body = {
  "grant_type": "client_credentials",
  "client_id": "<CLIENT_ID>",
  "client_secret": "<CLIENT_SECRET>"

};
const params = Object.keys(body || {}).map((key) => {
        return key + '=' + body[key];
      }).join('&');

const {data, headers} = await os.postRequest("<OAUTH_AUTHENTICATION_URL>", params,{headers: {'content-type': 'application/x-www-form-urlencoded'}});
const token = 'Bearer' + data.access_token;
os.context.set("request.headers.authorization", token);

Notes:

• "grant_type": Use "client_credentials" ., because "client_credentials" is the grant type in OAuth for server-side integration without user interaction.
• <CLIENT_ID> and <CLIENT_SECRET> refers to the user's code for the API being accessed, this will need to be provided by the user.
• <OAUTH_AUTHENTICATION_URL> refers to the URL the access token is being retrieved from. This URL will need to be provided by the user.

Now configure the Header:

With this and the rest of the required fields filled out, you've properly configured your Pre-request. Hitting Run Test should return a 200 OK Response.

If so, hit Save to finish your API Request.

That's all!

If you have any additional questions, concerns, or any feedback about OptiSigns, feel free to reach out to our support team at support@optisigns.com.