Getting 401 Unauthorized Error while trying to get OAuth token from ServiceNow to authenticate against Ansible Automation Platform

Solution Verified - Updated -

Environment

  • Ansible Automation Platform 2.4 and 2.5
  • ServiceNow

Issue

  • While trying to connect ServiceNow as an application in the Ansible Automation Platform, each time when clicking the Get Oauth Token button on the ServiceNow REST Message screen.

  • To fetch the OAuth Token to authenticate against the controller server. We get the below error:

    HTTP Error 401 - Unauthorized

Resolution

  • This is not an issue of Ansible Automation Platform, however, ServiceNow is returning 401 Unauthorized error as it is unable to parse the AUTH code.

Root Cause

  • The ServiceNow - Ansible Automation Platform workflow is described below:

    • When we click on the Get Oauth Token -> Authorize ServiceNow, It sends an API request to the controller/gateway:
      AAP 2.4 and older: https://conroller_url/api/o/authorize/
      AAP 2.5: https://gateway_url/o/authorize/
      The controller/gateway responds back with the Auth code, which can be seen in the url on SNow.

    • After which ServiceNow has to parse that auth code and send a POST request at:
      AAP 2.4 and older: https://conroller_url/api/o/token/
      AAP 2.5: https://gateway_url/o/token/
      to get the token using the AUTH code. The controller/gateway receives the request & sends back the Token.

    • ServiceNow can then use this token for any API requests to the controller/gateway.

    • But the issue here is, ServiceNow is returning 401 Unauthorized Error as it is unable to parse the AUTH code.

Diagnostic Steps

  • The workflow requests and responds can be verified by checking the nginx access.log while performing the above steps.
  • # tail -f /var/log/nginx/access.log

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