Add HttpClient

requirements.txt

@@ -1,3 +1,6 @@
 -e .
 pytest==4.2.0
 pytest-flakes==4.0.0
+# because of pip bug https://github.com/pypa/pip/issues/4780
+aiohttp==3.5.4
+certifi==2019.3.9

setup.py

@@ -7,5 +7,9 @@ setup(
     author='Galaxy team',
     author_email='galaxy@gog.com',
     packages=find_packages("src"),
-    package_dir={'': 'src'}
+    package_dir={'': 'src'},
+    install_requires=[
+        "aiohttp==3.5.4",
+        "certifi==2019.3.9"
+    ]
 )

src/galaxy/http.py

@@ -0,0 +1,41 @@
+import asyncio
+import ssl
+from http import HTTPStatus
+
+import aiohttp
+import certifi
+
+from galaxy.api.errors import (
+    AccessDenied, AuthenticationRequired,
+    BackendTimeout, BackendNotAvailable, BackendError, NetworkError, UnknownError
+)
+
+class AuthenticatedHttpClient:
+    def __init__(self, limit=20): # TODO timeout?
+        ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        ssl_context.load_verify_locations(certifi.where())
+        connector = aiohttp.TCPConnector(limit=limit, ssl=ssl_context)
+        self._session = aiohttp.ClientSession(connector=connector)
+
+    async def close(self):
+        await self._session.close()
+
+    async def request(self, method, *args, **kwargs):
+        try:
+            response = await self._session.request(method, *args, **kwargs)
+        except asyncio.TimeoutError:
+            raise BackendTimeout()
+        except aiohttp.ClientConnectionError:
+            raise NetworkError()
+        if response.status == HTTPStatus.UNAUTHORIZED:
+            raise AuthenticationRequired()
+        if response.status == HTTPStatus.FORBIDDEN:
+            raise AccessDenied()
+        if response.status == HTTPStatus.SERVICE_UNAVAILABLE:
+            raise BackendNotAvailable()
+        if response.status >= 500:
+            raise BackendError()
+        if response.status >= 400:
+            raise UnknownError()
+
+        return response