add Tag object to Tosca
diff --git a/xos/tosca/custom_types/xos.m4 b/xos/tosca/custom_types/xos.m4
index 4879584..a4b1b05 100644
--- a/xos/tosca/custom_types/xos.m4
+++ b/xos/tosca/custom_types/xos.m4
@@ -849,6 +849,21 @@
                 required: false
                 description: URL to the dashboard
 
+    tosca.nodes.Tag:
+        derived_from: tosca.nodes.Root
+        description: >
+            An XOS Tag
+        properties:
+            xos_base_props
+            name:
+                type: string
+                required: true
+                descrption: name of tag
+            value:
+                type: string
+                required: false
+                descrption: value of tag
+
     tosca.nodes.Compute.Container:
       derived_from: tosca.nodes.Compute
       description: >
@@ -985,6 +1000,9 @@
     tosca.relationships.DependsOn:
         derived_from: tosca.relationships.Root
 
+    tosca.relationships.TagsObject:
+        derived_from: tosca.relationships.Root
+
     tosca.capabilities.xos.Service:
         derived_from: tosca.capabilities.Root
         description: An XOS Service
diff --git a/xos/tosca/custom_types/xos.yaml b/xos/tosca/custom_types/xos.yaml
index fda4182..8c15379 100644
--- a/xos/tosca/custom_types/xos.yaml
+++ b/xos/tosca/custom_types/xos.yaml
@@ -1348,6 +1348,32 @@
                 required: false
                 description: URL to the dashboard
 
+    tosca.nodes.Tag:
+        derived_from: tosca.nodes.Root
+        description: >
+            An XOS Tag
+        properties:
+            no-delete:
+                type: boolean
+                default: false
+                description: Do not allow Tosca to delete this object
+            no-create:
+                type: boolean
+                default: false
+                description: Do not allow Tosca to create this object
+            no-update:
+                type: boolean
+                default: false
+                description: Do not allow Tosca to update this object
+            name:
+                type: string
+                required: true
+                descrption: name of tag
+            value:
+                type: string
+                required: false
+                descrption: value of tag
+
     tosca.nodes.Compute.Container:
       derived_from: tosca.nodes.Compute
       description: >
@@ -1484,6 +1510,9 @@
     tosca.relationships.DependsOn:
         derived_from: tosca.relationships.Root
 
+    tosca.relationships.TagsObject:
+        derived_from: tosca.relationships.Root
+
     tosca.capabilities.xos.Service:
         derived_from: tosca.capabilities.Root
         description: An XOS Service
diff --git a/xos/tosca/resources/tag.py b/xos/tosca/resources/tag.py
new file mode 100644
index 0000000..76d41cd
--- /dev/null
+++ b/xos/tosca/resources/tag.py
@@ -0,0 +1,53 @@
+import importlib
+import os
+import sys
+import tempfile
+sys.path.append("/opt/tosca")
+from translator.toscalib.tosca_template import ToscaTemplate
+from django.contrib.contenttypes.models import ContentType
+
+from core.models import Tag
+
+from xosresource import XOSResource
+
+class XOSTag(XOSResource):
+    provides = "tosca.nodes.Tag"
+    xos_model = Tag
+    name_field = None
+    copyin_props = ("name", "value")
+
+    def get_xos_args(self, throw_exception=True):
+        args = super(XOSTag, self).get_xos_args()
+
+        # Find the Tosca object that this Tag is pointing to, and return its
+        # content_type and object_id, which will be used in the GenericForeignKey
+        # django relation.
+
+        target_name = self.get_requirement("tosca.relationships.TagsObject", throw_exception=throw_exception)
+        if target_name:
+            target_model = self.engine.name_to_xos_model(self.user, target_name)
+            args["content_type"] = ContentType.objects.get_for_model(target_model)
+            args["object_id"] = target_model.id
+
+        # To uniquely identify a Tag, we must know the object that it is attached
+        # to as well as the name of the Tag.
+
+        if ("content_type" not in args) or ("object_id" not in args) or ("name" not in args):
+           if throw_exception:
+               raise Exception("Tag must specify TagsObject requirement and Name property")
+
+        return args
+
+    def get_existing_objs(self):
+        args = self.get_xos_args(throw_exception=True)
+
+        return Tag.objects.filter(content_type=args["content_type"],
+                                  object_id=args["object_id"],
+                                  name=args["name"])
+
+    def postprocess(self, obj):
+        pass
+
+    def can_delete(self, obj):
+        return super(XOSTag, self).can_delete(obj)
+
diff --git a/xos/tosca/samples/slicetag.yaml b/xos/tosca/samples/slicetag.yaml
new file mode 100644
index 0000000..ec064e3
--- /dev/null
+++ b/xos/tosca/samples/slicetag.yaml
@@ -0,0 +1,35 @@
+tosca_definitions_version: tosca_simple_yaml_1_0
+
+description: Setup CORD-related services -- vOLT, vCPE, vBNG.
+
+imports:
+   - custom_types/xos.yaml
+
+topology_template:
+  node_templates:
+    mysite_vsg:
+      type: tosca.nodes.Slice
+      properties:
+          no-create: True
+          no-delete: True
+          no-update: True
+
+    service_vsg:
+      type: tosca.nodes.Service
+      properties:
+          no-create: True
+          no-delete: True
+          no-update: True
+
+    mysite_vsg_foobar_tag:
+      type: tosca.nodes.Tag
+      properties:
+          name: foobar
+          value: xyz
+      requirements:
+          - target:
+              node: mysite_vsg
+              relationship: tosca.relationships.TagsObject
+          - service:
+              node: service_vsg
+              relationship: tosca.relationships.MemberOfService