Extraction of allowed environment variables from labels.

remoteappmanager/docker/docker_labels.py

@@ -42,4 +42,7 @@ def __init__(self, namespace, labels):
         # "vncapp", "webapp" or not present (for legacy apps). This will
         # affect the configurability of the image at startup.
         "type",
+        # environment variables that the container accepts.
+        # This is a sub-namespace. It will hold keys itself.
+        "env",
     ])

remoteappmanager/docker/image.py

@@ -1,5 +1,10 @@
+import string
+from traitlets import Unicode, HasTraits, Dict
+
 from remoteappmanager.docker.docker_labels import SIMPHONY_NS
-from traitlets import Unicode, HasTraits
+
+# Characters that are allowed in the environment variables.
+_ALLOWED_ENVCHARS = set(string.ascii_lowercase + string.digits + "-")
 
 
 class Image(HasTraits):
@@ -21,10 +26,17 @@ class Image(HasTraits):
     #: A long description of the image.
     description = Unicode()
 
-    #: The type of the image. This allows to differentiate image behavior
-    #: once started.
+    #: The type of the image.
     type = Unicode()
 
+    # A dictionary of supported environment variables that the
+    # container can accept as parameters. Note that the labels
+    # use a different notation, so a conversion takes place:
+    # dashes are converted to underscores, and letters are capitalized.
+    # e.g. x11-width -> X11_WIDTH
+    # Only keys are used at the moment.
+    env = Dict()
+
     @classmethod
     def from_docker_dict(cls, docker_dict):
         """Converts the dict response from the dockerpy library into an
@@ -53,4 +65,16 @@ def from_docker_dict(cls, docker_dict):
             self.description = labels.get(SIMPHONY_NS.description, '')
             self.type = labels.get(SIMPHONY_NS.type, '')
 
+            env_prefix = SIMPHONY_NS.env+"."
+            for env in [lab[len(env_prefix):]
+                        for lab in labels.keys()
+                        if lab.startswith(env_prefix)]:
+
+                if len(set(env) - _ALLOWED_ENVCHARS) != 0:
+                    # Skip badly formed stuff.
+                    continue
+
+                env = env.upper().replace("-", "_")
+                self.env[env] = None
+
         return self

remoteappmanager/docker/tests/test_image.py

@@ -23,6 +23,11 @@ def test_from_docker_dict_images(self):
     def test_from_docker_dict_inspect_image(self):
         docker_client = create_docker_client()
         image_dict = docker_client.inspect_image('image_id1')
+
+        labels = image_dict['Config']['Labels']
+        # Insert an unpalatable label for the envs.
+        labels['eu.simphony-project.docker.env.x11-height.whatever'] = None
+
         image = Image.from_docker_dict(image_dict)
 
         self.assertEqual(image.docker_id, image_dict["Id"])
@@ -34,10 +39,12 @@ def test_from_docker_dict_inspect_image(self):
             image.ui_name,
             image_dict['Config']["Labels"][SIMPHONY_NS.ui_name])
         self.assertEqual(image.type, 'vncapp')
+        self.assertEqual(image.env, {"X11_WIDTH": None})
 
     def test_missing_image_type(self):
         docker_client = create_docker_client()
         image_dict = docker_client.inspect_image('image_id2')
         image = Image.from_docker_dict(image_dict)
 
         self.assertEqual(image.type, '')
+        self.assertEqual(image.env, {})

remoteappmanager/tests/mocking/virtual/docker_client.py

@@ -36,6 +36,7 @@ def get_fake_image_labels(num=2):
             {'eu.simphony-project.docker.description': 'Ubuntu machine with mayavi preinstalled',  # noqa
              'eu.simphony-project.docker.ui_name': 'Mayavi 4.4.4',
              'eu.simphony-project.docker.type': 'vncapp',
+             'eu.simphony-project.docker.env.x11-width': None,
              },
             {'eu.simphony-project.docker.description': 'A vanilla Ubuntu installation'},  # noqa
         )