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Stackube User Guide

Tenant and Network Management

In this part, we will introduce tenant management and networking in Stackube. The tenant, which is 1:1 mapped with k8s namespace, is managed by using k8s CRD (previous TPR) to interact with Keystone. And the tenant is also 1:1 mapped with a network automatically, which is also implemented by CRD with standalone Neutron.

  1. Create a new tenant
$ cat test-tenant.yaml

apiVersion: "stackube.kubernetes.io/v1"
kind: Tenant
metadata:
  name: test
spec:
  username: "test"
  password: "password"

$ kubectl create -f test-tenant.yaml
  1. Check the auto-created namespace and network. Wait a while, the namespace and network for this tenant should be created automatically:
$ kubectl get namespace test
NAME      STATUS    AGE
test     Active    58m

$ kubectl -n test get network test -o yaml
apiVersion: stackube.kubernetes.io/v1
kind: Network
metadata:
  clusterName: ""
  creationTimestamp: 2017-08-03T11:58:31Z
  generation: 0
  name: test
  namespace: test
  resourceVersion: "3992023"
  selfLink: /apis/stackube.kubernetes.io/v1/namespaces/test/networks/test
  uid: 11d452eb-7843-11e7-8319-68b599b7918c
spec:
  cidr: 10.244.0.0/16
  gateway: 10.244.0.1
  networkID: ""
status:
  state: Active
  1. Check the Network and Tenant created in Neutron by Stackube controller.
$ source ~/keystonerc_admin
$ neutron net-list
+--------------------------------------+----------------------+----------------------------------+----------------------------------------------------------+
| id                                   | name                 | tenant_id                        | subnets                                                  |
+--------------------------------------+----------------------+----------------------------------+----------------------------------------------------------+
| 421d913a-a269-408a-9765-2360e202ad5b | kube-test-test       | 915b36add7e34018b7241ab63a193530 | bb446a53-de4d-4546-81fc-8736a9a88e3a 10.244.0.0/16       |
  1. Check the kube-dns pods created in the new namespace.
# kubectl -n test get pods
NAME                        READY     STATUS    RESTARTS   AGE
kube-dns-1476438210-37jv7   3/3       Running   0          1h
  1. Create pods and services in the new namespace.
# kubectl -n test run nginx --image=nginx
deployment "nginx" created
# kubectl -n test expose deployment nginx --port=80
service "nginx" exposed

# kubectl -n test get pods -o wide
NAME                        READY     STATUS    RESTARTS   AGE       IP            NODE
kube-dns-1476438210-37jv7   3/3       Running   0          1h        10.244.0.4    stackube
nginx-4217019353-6gjxq      1/1       Running   0          27s       10.244.0.10   stackube

# kubectl -n test run -i -t busybox --image=busybox sh
If you don't see a command prompt, try pressing enter.
/ # nslookup nginx
Server:    10.96.0.10
Address 1: 10.96.0.10

Name:      nginx
Address 1: 10.108.57.129 nginx.test.svc.cluster.local

/ # wget -O- nginx
Connecting to nginx (10.108.57.129:80)
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
-                    100% |*********************************************************************|   612   0:00:00 ETA
/ #
  1. Finally, remove the tenant.
$ kubectl delete tenant test
tenant "test" deleted
  1. Check Network in Neutron is also deleted by Stackube controller
$ neutron net-list
+--------------------------------------+---------+----------------------------------+----------------------------------------------------------+
| id                                   | name    | tenant_id                        | subnets                                                  |
+--------------------------------------+---------+----------------------------------+----------------------------------------------------------+

Persistent volume

This part describes the persistent volume design and usage in Stackube.

Standard Kubernetes volume
Stackube is a standard upstream Kubernetes cluster, so any type of `Kubernetes volumes
<https://kubernetes.io/docs/concepts/storage/volumes/>`_. can be used here, for example:

:

apiVersion: v1

kind: PersistentVolume

metadata:

name: nfs

spec:

capacity:

storage: 1Mi

accessModes:
  • ReadWriteMany

nfs:

# FIXME: use the right IP

server: 10.244.1.4

path: "/exports"

Please note since Stackube is a baremetal k8s cluster, cloud provider based volume like GCE, AWS etc is not supported by default.

But unless you are using emptyDir or hostPath, we will recommend always you the "Cinder RBD based block device as volume" described below in Stackube, this will bring you much higher performance.
==================================
Cinder RBD based block device as volume

The reason this volume type is preferred is: by default Stackube will run most of your workloads in a VM-based Pod, in this case directory sharing is used by hypervisor based runtime for volumes mounts, but this actually has more I/O overhead than bind mount.

On the other hand, the hypervisor Pod make it possible to mount block device directly to the VM-based Pod, so we can eliminates directory sharing.

In Stackube, we use a flexvolume to directly use Cinder RBD based block device as Pod volume. The usage is very simple:

apiVersion: v1
kind: Pod
metadata:
  name: web
  labels:
    app: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80
    volumeMounts:
    - name: nginx-persistent-storage
      mountPath: /var/lib/nginx
  volumes:
  - name: nginx-persistent-storage
    flexVolume:
      driver: "cinder/flexvolume_driver"
      fsType: ext4
      options:
        volumeID: daa7b4e6-1792-462d-ad47-78e900fed429

Please note the name of flexvolume is: "cinder/flexvolume_driver". Users are expected to provide a valid volume ID created with Cinder beforehand. Then a related RBD device will be attached to the VM-based Pod.

If your cluster is installed by stackube/devstack or following other stackube official guide, a /etc/kubernetes/cinder.conf file will be generated automatically on every node.

Otherwise, users are expected to write a /etc/kubernetes/cinder.conf on every node. The contents is like:

[Global]
auth-url = _AUTH_URL_
username = _USERNAME_
password = _PASSWORD_
tenant-name = _TENANT_NAME_
region = _REGION_
[RBD]
keyring = _KEYRING_

and also, users need to make sure flexvolume_driver binary is in /usr/libexec/kubernetes/kubelet-plugins/volume/exec/cinder~flexvolume_driver/ of every node.