Cluster components

Namespaces

kube-public
kube-system
default

Control plane

kube-apiserver
kube-scheduler
kube-controller-manager
kube-proxy
kube-flannel
coredns

Worker

join the cluster

kubeadm join --discovery-token 951876.7dd42a6e33a2b7af --discovery-token-ca-cert-hash sha256:1234..cdef 1.2.3.4:644

Helm

To install helm, install the client using the package manager of your OS. You currently need to deploy the server into your cluster with the helm init command :

→ kubectl apply -f helm-rbac.yaml
→ helm init --service-account tiller (1)
→ helm version
→ helm search stable/jenkins
→ helm install --name mediawiki stable/mediawiki
→ helm ls
→ helm delete mediawiki

1	In the next major version of helm (v3) tiller will not be necessary anymore

Dashboard

Install

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml

Configure

Add an admin-user and bind it to the dashboard

dashboard-user.yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: admin-user
  namespace: kube-system

kubectl apply -f dashboard-user.yaml
kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep admin-user | cut -f1 -d ' ')  (1)

1	output the admin authentication token

Connect

To connect to the dashboard, you need to use kubectl proxy :

kubectl proxy
xdg-open http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login (1)

1	http://localhost:8080/api/v1/namespaces/kube-system/services/kubernetes-dashboard might also work.

Load balancer

A bare metal cluster does not have any builtin load balancer. Metallb needs to be installed in order to provide such capabilities.

→ helm install --namespace metallb-system --name metallb stable/metallb
→ kubectl create -f metallb/config.yaml

Monitoring

Prometheus

Prometheus is an open source tool widely used to monitor containerized environments. It’s a pulling tool, which means that it doesn’t required agents.

Prometheus collects metrics from monitored targets by scraping metrics HTTP endpoints on these targets.

There is a natural integration with Kubernetes, Docker, cAdvisor and node-exporter.

To install on Kube, you need 2 yaml files :

prometheus-deployment.yaml : define the deployment procedure for the prometheus image.
prometheus-service.yaml : define the service which will be used to access the prometheus pods

You will also need to define the custom prometheus config through a configMap .

This is where you will created the config file prometheus need (alerts files and prometheus.yml file)

Node-exporter

Node-exporter retrieves metrics about the host where it runs (CPU, RAM, Disks)

Here is a kube config example :

      containers:
        - name: prometheus-node-exporter
          volumeMounts:
            - name: proc
              mountPath: /host/proc
              readOnly:  true
            - name: sys
              mountPath: /host/sys
              readOnly: true
            - name: root
              mountPath: /rootfs
              readOnly: true
            - name: cirb-srv
              mountPath: /srv
              readOnly: true
      volumes:
        - name: proc
          hostPath:
            path: /proc
        - name: sys
          hostPath:
            path: /sys
        - name: root
          hostPath:
            path: /rootfs
        - name: cirb-srv
          hostPath:
            path: /srv

cAdvisor

cAdvisor is an open source container resource usage and performance analysis agent. It retrieves info from containers present on host node where it’s installed.

There is no need to install it as it’s embedded in Kubelet component.