[#3970]Feature/Docusign Auth Module

cla-backend/cla/docusign_auth.py

@@ -0,0 +1,63 @@
+# Copyright The Linux Foundation and each contributor to CommunityBridge.
+# SPDX-License-Identifier: MIT
+
+"""
+docusign_auth.py contains all necessary objects and functions to perform authentication and authorization.
+"""
+
+
+import requests
+import os
+import jwt
+from time import time
+import cla
+import math
+
+
+INTEGRATION_KEY = cla.config.DOCUSIGN_INTEGRATOR_KEY
+INTEGRATION_SECRET = cla.config.DOCUSIGN_PRIVATE_KEY
+USER_ID = cla.config.DOCUSIGN_USER_ID
+OAUTH_BASE_URL = os.environ.get('DOCUSIGN_AUTH_SERVER')
+
+
+def request_access_token() -> str:
+    """
+    Requests an access token from the DocuSign OAuth2 service.
+    """
+    try:
+        cla.log.debug('Requesting access token from DocuSign OAuth2 service...')
+        url = f'https://{OAUTH_BASE_URL}/oauth/token'
+        headers = {
+            'Content-Type': 'application/x-www-form-urlencoded',
+        }
+        claims = {
+            "iss": INTEGRATION_KEY,
+            "sub": USER_ID,
+            "aud": OAUTH_BASE_URL,
+            "iat": time(),
+            "exp": time() + 3600,
+            "scope": "signature impersonation"
+        }
+        cla.log.debug(f'Claims: {claims}')
+        encoded_jwt = jwt.encode(claims, INTEGRATION_SECRET.encode(), algorithm='RS256')
+
+        payload = {
+            'grant_type': 'urn:ietf:params:oauth:grant-type:jwt-bearer',
+            'assertion': encoded_jwt
+        }
+
+        response = requests.post(url, headers=headers, data=payload)
+        data = response.json()
+        if 'token_type' in data and 'access_token' in data:
+            cla.log.debug('Successfully requested access token from DocuSign OAuth2 service.')
+            return data['access_token']
+        else:
+            cla.log.error('Unable to request access token from DocuSign OAuth2 service: ' + str(data))
+            raise Exception('Unable to request access token from DocuSign OAuth2 service: ' + str(data))
+
+    except Exception as err:
+        cla.log.error('Unable to request access token from DocuSign OAuth2 service: ' + str(err))
+        raise err
+
+
+