Make boto3 dependency optional (#30)

* Add boto3 to local requirements

* Add optional feature "aws" that depends on boto3

* Raise runtime error if boto3 is not installed

* Add instructions to install optional aws feature

* Test runtime error when boto3 is missing

* Rename fixture

* Add instructions to install aws feature

docs/source/installation.rst

@@ -12,3 +12,9 @@ First you need to install ``prettyconf`` library:
 .. code-block:: sh
 
     pip install prettyconf
+
+The ``AwsParameterStore`` configuration loader depends on the ``boto3`` package.
+If you need to use it, install ``prettyconf`` with the optional feature ``aws``:
+
+.. code-block:: sh
+    pip install prettyconf[aws]

prettyconf/loaders.py

@@ -2,8 +2,11 @@
 from configparser import ConfigParser, MissingSectionHeaderError, NoOptionError
 from glob import glob
 
-import boto3
-import botocore
+try:
+    import boto3
+    import botocore
+except ImportError:
+    boto3 = None
 
 from .exceptions import InvalidConfigurationFile, InvalidPath, MissingSettingsSection
 from .parsers import EnvFileParser
@@ -308,6 +311,11 @@ def __getitem__(self, item):
 
 class AwsParameterStore(AbstractConfigurationLoader):
     def __init__(self, path="/", aws_access_key_id=None, aws_secret_access_key=None, region_name="us-east-1"):
+        if not boto3:
+            raise RuntimeError(
+                'AwsParameterStore requires [aws] feature. Please install it: "pip install prettyconf[aws]"'
+            )
+
         self.path = path
         self.aws_access_key_id = aws_access_key_id
         self.aws_secret_access_key = aws_secret_access_key

requirements.txt

@@ -1,7 +1,8 @@
+boto3
+coveralls
 pytest
 pytest-cov
 pytest-runner
 Sphinx
 sphinx-rtd-theme
 twine
-coveralls

setup.py

@@ -39,7 +39,7 @@ def run(self):
     author="Osvaldo Santana Neto", author_email="[email protected]",
     license="MIT",
     packages=['prettyconf'],
-    install_requires=['boto3'],
+    extras_require={'aws': ['boto3']},
     platforms='any',
     classifiers=[
         'Development Status :: 5 - Production/Stable',

tests/test_parameterstore.py

@@ -1,3 +1,5 @@
+import importlib
+import sys
 from unittest import mock
 
 import pytest
@@ -43,6 +45,20 @@
 }
 
 
+@pytest.fixture
+def boto_not_installed():
+    sys.modules['boto3'] = None
+    importlib.reload(sys.modules['prettyconf.loaders'])
+    yield
+    sys.modules.pop('boto3')
+    importlib.reload(sys.modules['prettyconf.loaders'])
+
+
+def test_create_loader_boto_not_installed(boto_not_installed):
+    with pytest.raises(RuntimeError):
+        AwsParameterStore()
+
+
 @mock.patch("prettyconf.loaders.boto3")
 def test_basic_config(mock_boto):
     mock_boto.client.return_value.get_parameters_by_path.return_value = PARAMETER_RESPONSE