fix: Use Host provided by default context if no host is provided.

Related to issue: #3146

Signed-off-by: Alessandro Corradi <corradi.alessandro@mmfg.it>

Author: ale-cci

docker/api/client.py

@@ -18,6 +18,7 @@
     MINIMUM_DOCKER_API_VERSION,
     STREAM_HEADER_SIZE_BYTES,
 )
+from .. import context
 from ..errors import (
     DockerException,
     InvalidVersion,
@@ -124,6 +125,11 @@ def __init__(self, base_url=None, version=None,
                 'If using TLS, the base_url argument must be provided.'
             )
 
+        if base_url is None:
+            current_ctx = context.ContextAPI.get_current_context()
+            if current_ctx is not None:
+                base_url = current_ctx.Host
+
         self.base_url = base_url
         self.timeout = timeout
         self.headers['User-Agent'] = user_agent