check context in use targets a docker engine

Signed-off-by: aiordache <anca.iordache@docker.com>

compose/cli/docker_client.py

@@ -140,6 +140,11 @@ def docker_client(environment, version=None, context=None, tls_version=None):
         if tls:
             context.set_endpoint("docker", host=host, tls_cfg=tls, skip_tls_verify=not verify)
 
+    if not context.is_docker_host():
+        raise UserError(
+            "The platform targeted with the current context is not supported.\n"
+            "Make sure the context in use targets a Docker Engine.\n")
+
     kwargs['base_url'] = context.Host
     if context.TLSConfig:
         kwargs['tls'] = context.TLSConfig

requirements.txt

@@ -4,7 +4,7 @@ certifi==2020.4.5.1
 chardet==3.0.4
 colorama==0.4.3; sys_platform == 'win32'
 distro==1.5.0
-docker==4.2.1
+docker==4.2.2
 docker-pycreds==0.4.0
 dockerpty==0.4.1
 docopt==0.6.2