Kubernetes on an Ubuntu Machine (Single Node)

This guide helps you to create a Kubernetes with microk8s for PrimeHub. microk8s is only for the single-node use case.

Provision a cluster

microk8s could run on multi-platform, we demonstrate it in the following spec:

• Ubuntu 18.04 LTS
• Kubernetes 1.15 version
• IP address: 1.2.3.4
• Networking: allow 80 port for HTTP

Install microk8s

Install microk8s with snap

$ sudo snap install microk8s --classic --channel=1.15/stable
microk8s (1.15/stable) v1.15.10 from Canonical✓ installed

Add to group (re-login is required to get new permissions)

$ sudo usermod -a -G microk8s $USER

Wait microk8s ready

$ microk8s.status --wait-ready
microk8s is running
addons:
knative: disabled
jaeger: disabled
fluentd: disabled
gpu: disabled
cilium: disabled
storage: disabled
registry: disabled
rbac: disabled
ingress: disabled
dns: disabled
metrics-server: disabled
linkerd: disabled
prometheus: disabled
istio: disabled
dashboard: disabled

You could check it with microk8s.kubectl

$ microk8s.kubectl get nodes
NAME           STATUS   ROLES    AGE     VERSION
microk8s-doc   Ready    <none>   2m40s   v1.15.10

configure microk8s

Enable features

$ microk8s.enable storage
$ microk8s.enable dns
$ microk8s.enable rbac

Enable privileged in kube-apiserver

# add this line in `/var/snap/microk8s/current/args/kube-apiserver`
--allow-privileged

Apply it by restart microk8s:

sudo microk8s.stop
sudo microk8s.start

Install extra packages

sudo apt-get install nfs-common

Prepare kube config

$ mkdir ~/.kube
$ microk8s.kubectl config view --raw > ~/.kube/config

Verify config with kubectl

$ kubectl get nodes
NAME           STATUS   ROLES    AGE   VERSION
microk8s-doc   Ready    <none>   35m   v1.15.10

Install helm

Install helm 2.x binary. Please see the installation steps in prerequisites. Make sure the helm binary version is v2.x.x (v3.x.x is not supported yet)

$ helm version --client
Client: &version.Version{SemVer:"v2.16.1", GitCommit:"bbdfe5e7803a12bbdf97e94cd847859890cf4050", GitTreeState:"clean"}

Apply RBAC resources for helm

$ kubectl apply -f - << EOF
apiVersion: v1
kind: ServiceAccount
metadata:
  name: tiller
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: tiller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: tiller
    namespace: kube-system
EOF

Initialize helm in the cluster:

$ helm init --service-account tiller --wait

Verify helm versions:

$ helm version
Client: &version.Version{SemVer:"v2.16.1", GitCommit:"bbdfe5e7803a12bbdf97e94cd847859890cf4050", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.16.1", GitCommit:"bbdfe5e7803a12bbdf97e94cd847859890cf4050", GitTreeState:"clean"}

Nginx Ingress

$ helm install stable/nginx-ingress --namespace ingress-nginx \
  --name nginx-ingress --set controller.hostNetwork=true --set rbac.create=true

Quick Verification

Access nginx-ingress with the magic .nip.io domain, with your EXTERNAL-IP:

$ curl http://1.2.3.4.nip.io

The output will be 404 because nobody defines any Ingress resources:

default backend - 404

Configure GPU (optional)

• download and install Nvidia GPU drivers from official website
• enable GPU feature

microk8s.enable gpu

Configure snap (optional)

snap will update packages automatically. If you plan to use it in a production-ready environment, you could

• Set the update process run on a special time window, or delay it before a date
• Disable it by setting a wrong proxy

Please read the manual

Change Local Storage (optional)

It was possible to keep persistent volumes (PV) to external devices, for example

• a mounted external storage
• different path in the same device

For now, the microk8s-hostpath saves data at

/var/snap/microk8s/common/default-storage

It couldn't be changed and shouldn't be a symbolic link. If you want to save PV to a different location, the only way was using bind mount.

Here is a bind mount example:

LABEL=cloudimg-rootfs   /    ext4   defaults    0 0
LABEL=UEFI  /boot/efi   vfat    defaults    0 0
UUID=b6df830a-d881-4dc5-a8e4-aeea2d7ee6c0   /data   xfs defaults    0 0
/data   /var/snap/microk8s/common/default-storage   none    defaults,bind   0 0

• line 2 was an external storage mounted at /data
• line 3 was binding /data to /var/snap/microk8s/common/default-storage

Next

The cluster is ready to install PrimeHub. Please bring EXTERNAL-IP and StorageClass name to the next steps. They would be used in the value files of KeyCloak and PrimeHub

• EXTERNAL-IP: 1.2.3.4

• StorageClass name: microk8s-hostpath

  $ kubectl get storageclass
  NAME                          PROVISIONER            AGE
  microk8s-hostpath (default)   microk8s.io/hostpath   56m