Saturday, May 2, 2020

Install a local Kubernetes with MicroK8s on Ubuntu 18.04

About MicroK8S:

MicroK8s is a CNCF certified upstream Kubernetes deployment that runs entirely on workstation or edge device. Being a snap it runs all Kubernetes services natively (i.e. no virtual machines) while packing the entire set of libraries and binaries needed. Installation is limited by how fast you can download a couple of hundred megabytes and the removal of MicroK8s leaves nothing behind.
1. Requirement: 

One Linux machine with Ubuntu Installed.

2. Deployment of Microk8s:

 
sudo snap install microk8s --classic

MicroK8s is a snap and as such it is frequently updated to each release of Kubernetes. To follow a specific upstream release series it’s possible to select a channel during installation. For example, to follow the v1.17 series:


sudo snap install microk8s --classic --channel=1.17/stable

  snap info microk8s to see what versions are currently published.


name:      microk8s
summary:   Kubernetes for workstations and appliances
publisher: Canonical*
store-url: https://snapcraft.io/microk8s
contact:   https://github.com/ubuntu/microk8s
license:   unset
description: |
  MicroK8s is a small, fast, secure, single node Kubernetes that installs on
  just about any Linux box. Use it for offline development, prototyping,
  testing, or use it on a VM as a small, cheap, reliable k8s for CI/CD. It's
  also a great k8s for appliances - develop your IoT apps for k8s and deploy
  them to MicroK8s on your boxes.
commands:
  - microk8s.add-node
  - microk8s.cilium
  - microk8s.config
  - microk8s.ctr
  - microk8s.disable
  - microk8s.enable
  - microk8s.helm
  - microk8s.inspect
  - microk8s.istioctl
  - microk8s.join
  - microk8s.juju
  - microk8s.kubectl
  - microk8s.leave
  - microk8s.linkerd
  - microk8s
  - microk8s.remove-node
  - microk8s.reset
  - microk8s.start
  - microk8s.status
  - microk8s.stop
services:
  microk8s.daemon-apiserver:          simple, disabled, inactive
  microk8s.daemon-apiserver-kicker:   simple, disabled, inactive
  microk8s.daemon-cluster-agent:      simple, disabled, inactive
  microk8s.daemon-containerd:         simple, disabled, inactive
  microk8s.daemon-controller-manager: simple, disabled, inactive
  microk8s.daemon-etcd:               simple, disabled, inactive
  microk8s.daemon-flanneld:           simple, disabled, inactive
  microk8s.daemon-kubelet:            simple, disabled, inactive

  microk8s.daemon-proxy:              simple, disabled, inactive

  microk8s.daemon-scheduler:          simple, disabled, inactive

snap-id:      EaXqgt1lyCaxKaQCU349mlodBkDCXRcg

tracking:     1.17/stable
refresh-date: today at 09:46 IST
channels:
  latest/stable:    v1.18.2         2020-04-27 (1378) 201MB classic
  latest/candidate: v1.18.2         2020-04-30 (1383) 201MB classic
  latest/beta:      v1.18.2         2020-04-30 (1383) 201MB classic
  latest/edge:      v1.18.2         2020-05-01 (1391) 211MB classic
  dqlite/stable:    --
  dqlite/candidate: --
  dqlite/beta:      --
  dqlite/edge:      v1.16.2         2019-11-07 (1038) 189MB classic
  1.19/stable:      --
  1.19/candidate:   --
  1.19/beta:        --
  1.19/edge:        v1.19.0-alpha.1 2020-03-26 (1311) 201MB classic
  1.18/stable:      v1.18.2         2020-04-27 (1379) 201MB classic
  1.18/candidate:   v1.18.2         2020-04-27 (1379) 201MB classic
  1.18/beta:        v1.18.2         2020-04-27 (1379) 201MB classic
  1.18/edge:        v1.18.2         2020-04-29 (1387) 201MB classic
  1.17/stable:      v1.17.5         2020-05-02 (1355) 179MB classic
  1.17/candidate:   v1.17.5         2020-04-17 (1355) 179MB classic
  1.17/beta:        v1.17.5         2020-04-17 (1355) 179MB classic
  1.17/edge:        v1.17.5         2020-04-29 (1388) 179MB classic
  1.16/stable:      v1.16.8         2020-03-27 (1302) 179MB classic
  1.16/candidate:   v1.16.8         2020-03-27 (1302) 179MB classic

3. Configure your firewall to allow pod-to-pod and pod-to-internet communication:

sudo ufw allow in on cni0 && sudo ufw allow out on cni0
sudo ufw default allow routed
4. Enable Add-ons:
By default we get a barebones upstream Kubernetes. Additional services, such as dashboard or kube-dns, can be enabled by running the microk8s.enable command:
microk8s.enable dashboard dns
These addons can be disabled at anytime by running the microk8s.disable command:
microk8s.disable dashboard dns
With microk8s.status you can see the list of available addons and the ones currently enabled.





List of the most important addons

  • dns: Deploy DNS. This addon may be required by others, thus we recommend you always enable it.
  • dashboard: Deploy kubernetes dashboard as well as grafana and influxdb.
  • storage: Create a default storage class. This storage class makes use of the hostpath-provisioner pointing to a directory on the host.
  • ingress: Create an ingress controller.
  • gpu: Expose GPU(s) to MicroK8s by enabling the nvidia-docker runtime and nvidia-device-plugin-daemonset. Requires NVIDIA drivers to be already installed on the host system.
  • istio: Deploy the core Istio services. You can use the microk8s.istioctl command to manage your deployments.
  • registry: Deploy a docker private registry and expose it on localhost:32000. The storage addon will be enabled as part of this addon.
4. Accessing the Kubernetes and Grafana dashboards:

microk8s.kubectl get all --all-namespaces


5. Access Kubernetes and Grafana dashboard:

Refer above snapshot. To access dashboard open in your browser to https://10.152.183.46:443 and you will see the kubernetes dashboard UI. To access the dashboard use the default token retrieved with:

 
token=$(microk8s.kubectl -n kube-system get secret | grep default-token | cut -d " " -f1)
microk8s.kubectl -n kube-system describe secret $token
To access Grafana dashboard:

microk8s.kubectl cluster-info








We need to point our browser to https://127.0.0.1:16443/api/v1/namespaces/kube-system/services/monitoring-grafana/proxy and use the username and password shown with microk8s.config.

6. Host your first service in Kubernetes



We start by creating a microbot deployment with two pods via the kubectl cli:
microk8s.kubectl create deployment microbot --image=dontrebootme/microbot:v1
microk8s.kubectl scale deployment microbot --replicas=2
To expose our deployment we need to create a service:
microk8s.kubectl expose deployment microbot --type=NodePort --port=80 --name=microbot-service

microk8s.kubectl get all --all-namespaces
you will see the service "microbot-service" which is accessible on port "80" of Node IP.
7. Useful additional commands:



There are many commands that ship with MicroK8s. We’ve only seen the essential ones in this tutorial. Explore the others at your own convenience:
  • microk8s.status: Provides an overview of the MicroK8s state (running / not running) as well as the set of enabled addons
  • microk8s.enable: Enables an addon
  • microk8s.disable: Disables an addon
  • microk8s.kubectl: Interact with kubernetes
  • microk8s.config: Shows the kubernetes config file
  • microk8s.istioctl: Interact with the istio services; needs the istio addon to be enabled
  • microk8s.inspect: Performs a quick inspection of the MicroK8s intallation
  • microk8s.reset: Resets the infrastructure to a clean state
  • microk8s.stop: Stops all kubernetes services
  • microk8s.start: Starts MicroK8s after it is being stopped
8.  Finally, once you have enough dirty hand with MicroK8s, don't forget to stop cluster with "microk8s.stop"

9. Build-in inspection tool:

sudo microk8s inspect
10. Checking Pods logs:

microk8s kubectl get pods
microk8s kubectl logs 
# All images running in a cluster
kubectl get pods -A -o=custom-columns='DATA:spec.containers[*].image'

 # All images excluding "k8s.gcr.io/coredns:1.6.2"
kubectl get pods -A -o=custom-columns='DATA:spec.containers[?(@.image!="k8s.gcr.io/coredns:1.6.2")].image'

# All fields under metadata regardless of name
kubectl get pods -A -o=custom-columns='DATA:metadata.*'
on

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