#135: Implement login function for python ICAT backend

- Because this backend can use different mechanisms, I've changed the DB backend so it can use a mechanism as per the request body
- Any installed mechanism can be used, though if one isn't supplied, it defaults to simple

common/backend.py

@@ -10,7 +10,7 @@ class Backend(ABC):
     def login(self, credentials):
         """
         Attempt to log a user in using the provided credentials
-        :param credentials: The user's credentials
+        :param credentials: The user's credentials (including mechanism)
         :returns: a session ID
         """
         pass

common/config.py

@@ -24,6 +24,12 @@ def get_db_url(self):
         except:
             sys.exit("Missing config value, DB_URL")
 
+    def get_icat_url(self):
+        try:
+            return self.config["ICAT_URL"]
+        except:
+            sys.exit("Missing config value, ICAT_URL")
+
     def get_log_level(self):
         try:
             return self.config["log_level"]

common/database_backend.py

@@ -9,6 +9,8 @@
 from common.exceptions import AuthenticationError
 import datetime
 
+import logging
+log = logging.getLogger()
 
 class DatabaseBackend(Backend):
     """
@@ -18,7 +20,7 @@ class DatabaseBackend(Backend):
     def login(self, credentials):
         if credentials["username"] == "user" and credentials["password"] == "password":
             session_id = str(uuid.uuid1())
-            insert_row_into_table(SESSION, SESSION(ID=session_id, USERNAME="simple/root",
+            insert_row_into_table(SESSION, SESSION(ID=session_id, USERNAME=f"{credentials['mechanism']}/root",
                                                    EXPIREDATETIME=datetime.datetime.now() + datetime.timedelta(days=1)))
             return session_id
         else:

common/python_icat_backend.py

@@ -1,15 +1,32 @@
+import logging
+
+import icat.client
+from icat.exception import ICATSessionError
+
 from common.backend import Backend
-from common.helpers import requires_session_id, queries_records
-#from common.python_icat_helpers import
+from common.helpers import queries_records, requires_session_id
+from common.config import config
+from common.exceptions import AuthenticationError
+from common.models.db_models import SESSION
 
+log = logging.getLogger()
 
 class PythonICATBackend(Backend):
     """
     Class that contains functions to access and modify data in an ICAT database directly
     """
 
-    def login(self, credentials, mnemonic):
-        pass
+    def login(self, credentials):
+        icat_server_url = config.get_icat_url()
+        client = icat.client.Client(icat_server_url, checkCert=False)
+        # Syntax for Python ICAT
+        login_details = {'username': credentials['username'], 'password': credentials['password']}
+
+        try:
+            session_id = client.login(credentials["mechanism"], login_details)
+            return session_id
+        except ICATSessionError:
+            raise AuthenticationError("User credentials are incorrect")
 
     @requires_session_id
     def get_session_details(self, session_id):
@@ -86,4 +103,3 @@ def get_instrument_facilitycycle_investigations_with_filters(self, session_id, i
     def count_instrument_facilitycycles_investigations_with_filters(self, session_id, instrument_id, facilitycycle_id, filters):
         pass
         #return get_investigations_for_instrument_in_facility_cycle_count(instrument_id, facilitycycle_id, filters)
-

config.json.example

@@ -1,6 +1,7 @@
 {
   "backend": "db",
   "DB_URL": "mysql+pymysql://root:rootpw@localhost:13306/icatdb",
+  "ICAT_URL": "https://localhost.localdomain:8181",
   "log_level": "WARN",
   "debug_mode": false,
   "generate_swagger": false,

src/resources/non_entities/sessions_endpoints.py

@@ -54,6 +54,9 @@ def post(self):
         """
         if not (request.data and "username" in request.json and "password" in request.json):
             return "Bad request", 400
+        # If no mechanism is present in request body, default to simple
+        if not ("mechanism" in request.json):
+            request.json["mechanism"] = "simple"
         try:
             return {"sessionID": backend.login(request.json)}, 201
         except AuthenticationError: