Make orchestrator field optional

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

docker/context/api.py

@@ -14,11 +14,11 @@ class ContextAPI(object):
     Contains methods for context management:
     create, list, remove, get, inspect.
     """
-    DEFAULT_CONTEXT = Context("default")
+    DEFAULT_CONTEXT = Context("default", "swarm")
 
     @classmethod
     def create_context(
-            cls, name, orchestrator="swarm", host=None, tls_cfg=None,
+            cls, name, orchestrator=None, host=None, tls_cfg=None,
             default_namespace=None, skip_tls_verify=False):
         """Creates a new context.
         Returns:
@@ -38,9 +38,7 @@ class ContextAPI(object):
         >>> print(ctx.Metadata)
         {
             "Name": "test",
-            "Metadata": {
-                "StackOrchestrator": "swarm"
-            },
+            "Metadata": {},
             "Endpoints": {
                 "docker": {
                     "Host": "unix:///var/run/docker.sock",
@@ -57,7 +55,9 @@ class ContextAPI(object):
         ctx = Context.load_context(name)
         if ctx:
             raise errors.ContextAlreadyExists(name)
-        endpoint = "docker" if orchestrator == "swarm" else orchestrator
+        endpoint = "docker"
+        if orchestrator and orchestrator != "swarm":
+            endpoint = orchestrator
         ctx = Context(name, orchestrator)
         ctx.set_endpoint(
             endpoint, host, tls_cfg,
@@ -79,9 +79,7 @@ class ContextAPI(object):
         >>> print(ctx.Metadata)
         {
             "Name": "test",
-            "Metadata": {
-                "StackOrchestrator": "swarm"
-            },
+            "Metadata": {},
             "Endpoints": {
                 "docker": {
                 "Host": "unix:///var/run/docker.sock",

docker/context/context.py

@@ -11,7 +11,7 @@ from docker.context.config import get_context_host
 
 class Context:
     """A context."""
-    def __init__(self, name, orchestrator="swarm", host=None, endpoints=None,
+    def __init__(self, name, orchestrator=None, host=None, endpoints=None,
                  tls=False):
         if not name:
             raise Exception("Name not provided")
@@ -19,7 +19,7 @@ class Context:
         self.orchestrator = orchestrator
         if not endpoints:
             default_endpoint = "docker" if (
-                orchestrator == "swarm"
+                not orchestrator or orchestrator == "swarm"
                 ) else orchestrator
             self.endpoints = {
                 default_endpoint: {
@@ -85,7 +85,8 @@ class Context:
                         context {} : {}""".format(name, e))
 
             return (
-                metadata["Name"], metadata["Metadata"]["StackOrchestrator"],
+                metadata["Name"],
+                metadata["Metadata"].get("StackOrchestrator", None),
                 metadata["Endpoints"])
         return None, None, None
 
@@ -162,7 +163,7 @@ class Context:
 
     @property
     def Host(self):
-        if self.orchestrator == "swarm":
+        if not self.orchestrator or self.orchestrator == "swarm":
             return self.endpoints["docker"]["Host"]
         return self.endpoints[self.orchestrator]["Host"]
 
@@ -172,18 +173,19 @@ class Context:
 
     @property
     def Metadata(self):
+        meta = {}
+        if self.orchestrator:
+            meta = {"StackOrchestrator": self.orchestrator}
         return {
             "Name": self.name,
-            "Metadata": {
-                "StackOrchestrator": self.orchestrator
-            },
+            "Metadata": meta,
             "Endpoints": self.endpoints
         }
 
     @property
     def TLSConfig(self):
         key = self.orchestrator
-        if key == "swarm":
+        if not key or key == "swarm":
             key = "docker"
         if key in self.tls_cfg.keys():
             return self.tls_cfg[key]