Add documentation for using namespace labels for configuring defaults.

krsoninikhil · krsoninikhil · commit da2ab865e04f · 2019-02-01T23:14:33.000+05:30
Signed-off-by: Nikhil Soni &lt;krsoninikhil@gmail.com&gt;
diff --git a/docs/namespaces.md b/docs/namespaces.md
@@ -34,9 +34,7 @@ Filesystem paths, IDs, and other system level resources must be namespaced for a
 
 Simply create a new `context` and set your application's namespace on the `context`.
 Make sure to use a unique namespace for applications that does not conflict with existing namespaces. The namespaces
-API, or the `ctr namespaces` client command, can be used to query/list and create new namespaces. Note that namespaces
-can have a list of labels associated with the namespace. This can be useful for associating metadata with a particular
-namespace.
+API, or the `ctr namespaces` client command, can be used to query/list and create new namespaces.
 
 ```go
 ctx := context.Background()
@@ -49,6 +47,19 @@ var (
 )
 ```
 
+## Namespace Labels
+
+Namespaces can have a list of labels associated with the namespace. This can be useful for associating metadata with a particular namespace.
+Labels can also be used to configure the defaults for containerd, for example:
+
+```bash
+> sudo ctr namespaces label k8s.io containerd.io/defaults/snapshotter=btrfs
+> sudo ctr namespaces label k8s.io containerd.io/defaults/runtime=testRuntime
+```
+
+This will set the default snapshotter as `btrfs` and runtime as `testRuntime`.
+Note that currently only these two labels are used to configure the defaults and labels of `default` namespace are not considered for the same.
+
 ## Inspecting Namespaces
 
 If we need to inspect containers, images, or other resources in various namespaces the `ctr` tool allows you to do this.
