Add basic authentication in the server (#1670)

* Add basic authentication in the server

A pattern for creating authentication methods is introduced, with three
authentication types defined:
  none - no authentication
  session - like the current session based auth used for user annotations
  test - used to test the login/logout process end to end

The config endpoint now returns informations about the authentication, like if
the user is authenticated and their username.  The redirect uri's for login and
logout are also returned if the authentication type requires login

This is the first a several PRs for authentication.

*. Update server tests to avoid hardcoded ports

test_api and test_nan_rest now use a common function for starting a test server,
than will initially choose a random port.

server/common/app_config.py

@@ -16,6 +16,7 @@ from server.common.annotations import AnnotationsLocalFile
 from server.common.utils import custom_format_warning
 import server.compute.diffexp_cxg as diffexp_tiledb
 from server.common.data_locator import discover_s3_region_name
+from server.auth.auth import AuthTypeFactory
 
 DEFAULT_SERVER_PORT = 5005
 # anything bigger than this will generate a special message
@@ -194,6 +195,7 @@ class AppConfig(object):
         server_config = self.server_config
         dataset_config = data_adaptor.dataset_config
         annotation = dataset_config.user_annotations
+        auth = server_config.auth
 
         # FIXME The current set of config is not consistently presented:
         # we have camalCase, hyphen-text, and underscore_text
@@ -257,6 +259,18 @@ class AppConfig(object):
             "diffexp_cellcount_max": server_config.limits__diffexp_cellcount_max,
         }
 
+        if dataset_config.app__authentication_enable and auth.is_valid():
+            config["authentication"] = {
+                "is_authenticated": auth.is_authenticated(),
+                "requires_client_login": auth.requires_client_login(),
+                "username": auth.get_username(),
+            }
+            if auth.requires_client_login():
+                config["authentication"].update({
+                    "login": auth.get_login_url(data_adaptor),
+                    "logout" : auth.get_logout_url(data_adaptor),
+                })
+
         return c
 
 
@@ -366,6 +380,7 @@ class ServerConfig(BaseConfig):
     def __init__(self, app_config, default_config):
         dictval_cases = [
             ("app", "csp_directives"),
+            ("authentication", "params"),
             ("adaptor", "cxg_adaptor", "tiledb_ctx"),
             ("multi_dataset", "dataroot"),
         ]
@@ -384,6 +399,9 @@ class ServerConfig(BaseConfig):
             self.app__server_timing_headers = dc["app"]["server_timing_headers"]
             self.app__csp_directives = dc["app"]["csp_directives"]
 
+            self.authentication__type = dc["authentication"]["type"]
+            self.authentication__params = dc["authentication"]["params"]
+
             self.multi_dataset__dataroot = dc["multi_dataset"]["dataroot"]
             self.multi_dataset__index = dc["multi_dataset"]["index"]
             self.multi_dataset__allowed_matrix_types = dc["multi_dataset"]["allowed_matrix_types"]
@@ -414,8 +432,12 @@ class ServerConfig(BaseConfig):
         # The matrix data cache manager is created during the complete_config and stored here.
         self.matrix_data_cache_manager = None
 
+        # The authentication object (BCM -- better name)
+        self.auth = None
+
     def complete_config(self, context):
         self.handle_app(context)
+        self.handle_authentication(context)
         self.handle_data_locator(context)
         self.handle_adaptor(context)  # may depend on data_locator
         self.handle_single_dataset(context)  # may depend on adaptor
@@ -484,6 +506,14 @@ class ServerConfig(BaseConfig):
                 elif not isinstance(v, str):
                     raise ConfigurationError("CSP directive value must be a string or list of strings.")
 
+    def handle_authentication(self, context):
+        self.check_attr("authentication__type", (type(None), str))
+        self.check_attr("authentication__params", (type(None), dict))
+        self.auth = AuthTypeFactory.create(self.authentication__type)
+        if self.auth is None:
+            raise ConfigurationError(f"Unknown authentication type: {self.authentication__type}")
+        self.auth.set_params(self.authentication__params)
+
     def handle_data_locator(self, context):
         self.check_attr("data_locator__s3__region_name", (type(None), bool, str))
         if self.data_locator__s3__region_name is True:
@@ -660,6 +690,7 @@ class DatasetConfig(BaseConfig):
             self.app__inline_scripts = dc["app"]["inline_scripts"]
             self.app__about_legal_tos = dc["app"]["about_legal_tos"]
             self.app__about_legal_privacy = dc["app"]["about_legal_privacy"]
+            self.app__authentication_enable = dc["app"]["authentication_enable"]
 
             self.presentation__max_categories = dc["presentation"]["max_categories"]
             self.presentation__custom_colors = dc["presentation"]["custom_colors"]
@@ -696,6 +727,7 @@ class DatasetConfig(BaseConfig):
         self.check_attr("app__inline_scripts", list)
         self.check_attr("app__about_legal_tos", (type(None), str))
         self.check_attr("app__about_legal_privacy", (type(None), str))
+        self.check_attr("app__authentication_enable", bool)
 
         # scripts can be string (filename) or dict (attributes).   Convert string to dict.
         scripts = []
@@ -721,6 +753,13 @@ class DatasetConfig(BaseConfig):
         self.check_attr("user_annotations__ontology__obo_location", (type(None), str))
 
         if self.user_annotations__enable:
+            server_config = self.app_config.server_config
+            if not self.app__authentication_enable:
+                raise ConfigurationError("user annotations requires authentication to be enabled")
+            if not server_config.auth.is_valid():
+                auth_type = server_config.authentication__type
+                raise ConfigurationError(f"authentication method {auth_type} is not compatible with user annotations")
+
             # TODO, replace this with a factory pattern once we have more than one way
             # to do annotations.  currently only local_file_csv
             if self.user_annotations__type != "local_file_csv":