fix: silently ignore missing configuration file

While attempting to read configuration properties from
the config file specified via ${IBM_CREDENTIALS_FILE}, the
read_external_sources() function should silently ignore
an error if the file doesn't exist, and then proceed
to the next step of the config algorithm.
This was not working correctly, but this commit fixes that.

Author: padamstx

Authentication.md

@@ -48,7 +48,7 @@ export EXAMPLE_SERVICE_PASSWORD=mypassword
 ```
 Application code:
 ```python
-from ibm_cloud_sdk_core.authenticators import get_authenticator_from_environment
+from ibm_cloud_sdk_core import get_authenticator_from_environment
 
 authenticator = get_authenticator_from_environment('example_service')
 service = ExampleService(authenticator=authenticator)
@@ -80,7 +80,7 @@ export EXAMPLE_SERVICE_BEARER_TOKEN=<the bearer token value>
 ```
 Application code:
 ```python
-from ibm_cloud_sdk_core.authenticators import get_authenticator_from_environment
+from ibm_cloud_sdk_core import get_authenticator_from_environment
 
 authenticator = get_authenticator_from_environment('example_service')
 service = ExampleService(authenticator=authenticator)
@@ -133,7 +133,7 @@ export EXAMPLE_SERVICE_APIKEY=myapikey
 ```
 Application code:
 ```python
-from ibm_cloud_sdk_core.authenticators import get_authenticator_from_environment
+from ibm_cloud_sdk_core import get_authenticator_from_environment
 
 authenticator = get_authenticator_from_environment('example_service')
 service = ExampleService(authenticator=authenticator)
@@ -179,7 +179,7 @@ export EXAMPLE_SERVICE_URL=https://mycp4dhost.com/
 ```
 Application code:
 ```python
-from ibm_cloud_sdk_core.authenticators import get_authenticator_from_environment
+from ibm_cloud_sdk_core import get_authenticator_from_environment
 
 authenticator = get_authenticator_from_environment('example_service')
 service = ExampleService(authenticator=authenticator)
@@ -203,7 +203,7 @@ export EXAMPLE_SERVICE_AUTH_TYPE=noauth
 ```
 Application code:
 ```python
-from ibm_cloud_sdk_core.authenticators import get_authenticator_from_environment
+from ibm_cloud_sdk_core import get_authenticator_from_environment
 
 authenticator = get_authenticator_from_environment('example_service')
 service = ExampleService(authenticator=authenticator)

Makefile

@@ -4,6 +4,8 @@
 
 setup: deps dev_deps install_project
 
+all: setup test-unit lint
+
 deps:
 	python -m pip install --upgrade pip
 	python -m pip install -r requirements.txt

ibm_cloud_sdk_core/utils.py

@@ -1,6 +1,6 @@
 # coding: utf-8
 
-# Copyright 2019 IBM All Rights Reserved.
+# Copyright 2019, 2021 IBM All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -234,31 +234,36 @@ def __read_from_credential_file(service_name: str,
     """
     default_credentials_file_name = 'ibm-credentials.env'
 
-    # File path specified by an env variable
+    # 1. ${IBM_CREDENTIALS_FILE}
     credential_file_path = getenv('IBM_CREDENTIALS_FILE')
 
-    # Current working directory
+    # 2. <current-working-directory>/ibm-credentials.env
     if credential_file_path is None:
         file_path = join(getcwd(), default_credentials_file_name)
         if isfile(file_path):
             credential_file_path = file_path
 
-    # Home directory
+    # 3. <user-home-directory>/ibm-credentials.env
     if credential_file_path is None:
         file_path = join(expanduser('~'), default_credentials_file_name)
         if isfile(file_path):
             credential_file_path = file_path
 
     config = {}
     if credential_file_path is not None:
-        with open(credential_file_path, 'r') as fobj:
-            for line in fobj:
-                key_val = line.strip().split(separator, 1)
-                if len(key_val) == 2:
-                    key = key_val[0]
-                    value = key_val[1]
-                    _parse_key_and_update_config(config, service_name, key,
-                                                 value)
+        try:
+            with open(credential_file_path, 'r') as fobj:
+                for line in fobj:
+                    key_val = line.strip().split(separator, 1)
+                    if len(key_val) == 2:
+                        key = key_val[0]
+                        value = key_val[1]
+                        _parse_key_and_update_config(config, service_name, key,
+                                                     value)
+        except OSError:
+            # just absorb the exception and make sure we return an empty response
+            config = {}
+
     return config
 
 

test/test_utils.py

@@ -1,11 +1,28 @@
 # pylint: disable=missing-docstring
+# coding: utf-8
+
+# Copyright 2019, 2021 IBM All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 import os
 import datetime
 
 from typing import Optional
 from ibm_cloud_sdk_core import string_to_datetime, datetime_to_string, get_authenticator_from_environment
 from ibm_cloud_sdk_core import string_to_date, date_to_string
 from ibm_cloud_sdk_core import convert_model, convert_list
+from ibm_cloud_sdk_core import read_external_sources
 from ibm_cloud_sdk_core.authenticators import BasicAuthenticator, IAMAuthenticator
 
 
@@ -375,3 +392,28 @@ def test_multi_word_service_name():
     assert authenticator is not None
     assert authenticator.token_manager.apikey == '5678efgh'
     del os.environ['PERSONALITY_INSIGHTS_APIKEY']
+
+
+def test_read_external_sources_1():
+    # Set IBM_CREDENTIALS_FILE to a non-existent file (should be silently ignored).
+    bad_file_path = os.path.join(os.path.dirname(__file__), 'NOT_A_FILE')
+    os.environ['IBM_CREDENTIALS_FILE'] = bad_file_path
+
+    # This env var should take precendence since the config file wasn't found.
+    os.environ['SERVICE_1_URL'] = 'https://good-url.com'
+
+    config = read_external_sources('service_1')
+    assert config.get('URL') == 'https://good-url.com'
+
+
+def test_read_external_sources_2():
+    # The config file should take precedence over the env variable.
+    config_file = os.path.join(os.path.dirname(__file__),
+                               '../resources/ibm-credentials.env')
+    os.environ['IBM_CREDENTIALS_FILE'] = config_file
+
+    # This should be ignored since IBM_CREDENTIALS_FILE points to a valid file.
+    os.environ['SERVICE_1_URL'] = 'wrong-url'
+
+    config = read_external_sources('service_1')
+    assert config.get('URL') == 'service1.com/api'