Make docker optional

scone/default/utensils/docker_utensils.py

@@ -1,7 +1,11 @@
 from typing import Optional
 
 import attr
-import docker.errors
+
+try:
+    import docker.errors
+except ImportError:
+    docker = None
 
 from scone.common.chanpro import Channel
 from scone.sous import Utensil

setup.py

@@ -53,7 +53,9 @@ EXTRAS = {
     ],
     "sous": EX_SOUS_ALL,
     "sous-core": EX_SOUS_BASE,
-    "sous-pg": EX_SOUS_PG
+    "sous-pg": EX_SOUS_PG,
+
+    "docker": ["docker"]  # TODO do this more properly if we can...
 }
 
 # The rest you shouldn't have to touch too much :)