K8s Hands-on - 1
One can find many useful articles about basic kubectl commands and minikube. Katacoda is one of the best website, for online hands-on with k8s. Here, I just shared my experience with katacoda and on-premise minikube cluster.
First, one need set few alias at .bashrc file.
alias k=kubectl
alias kg=kubectl get
alias m=minikube
Minikube
By default, minikube runs with 2 CPUs and 2GB RAM. It makes the system slow. minikube needs minimum 2 CPU. With trial and error i found, 1.5 GB is sufficient to run minikube.
minikube start --memory 1536
Now few commands
kubectl config view
kubectl cluster-info
kubectl get nodes
kubectl desscribe node
minikube ip
minikube dashboard
minikube addons enable heapster
minikube addons list
minikube service list
minikube status
Service related commands
One can use svc in place of service for kubectl command, not for minikube commands
kubectl get svc
command lists services only from default namespace, while
minikube service list
command list services from all namespace.
One can add "-n kube-system" for kubectl command.
kubectl get svc -n kube-system
One can also add "--all-namespaces" for kubectl command
kubectl get svc --all-namespaces
Virtual Box
/home folder of host OS is mounted as /hosthome folder inside VirtualBox
To login to virtual box
minikube ssh
OR
ssh to minikube's IP address with docker/tcuser
Note: None of the above methods work at Katacoda for first scenario "Launching single Node cluster" under "Introduction to Kubernets" hands-on.
Here are comparision of IP address and various interface within virtual box and outside virtual box
Deployment
I found, below 3 basic images to begin with
kubectl create deployment x --image=katacoda/docker-http-server
kubectl create deployment k --image=k8s.gcr.io/echoserver:1.10
kubectl create deployment i --image=nginx
The dployment should be exposed with below commans
For http-server and nginx
kubectl expose deployment x--port=80 --type=NodePort
kubectl expose deployment i --port=80 --type=NodePort
For echo-server
kubectl expose deployment k--port=8080 --type=NodePort
The deployment can be removed with
kubectl delete svc
Access Service
1.
As per katacoda, the service can be tested with curl command as below
export PORT=$(kubectl get svc first-deployment -o go-template='{{range.spec.ports}}{{if .nodePort}}{{.nodePort}}{{"\n"}}{{end}}{{end}}')
echo "Accessing host01:$PORT"
curl host01:$PORT
There are alternate ways also
2.
curl $(minikube service x --url)
3. The below command invoke browser with required URL
minikube service x
4. Using proxy
kubectl proxy
Open URL in browser
http://127.0.0.1:8001/api/v1/namespaces/default/pods/POD_NAME/proxy/
POD
To get details about pod in JSON format
1.
kubectl get pods -o json
2.
kubectl proxy
Open URL in browser
http://127.0.0.1:8001/api/v1/namespaces/default/pods/
To login to pod
kubectl exec -it $POD_NAME bash
To get enviornment variables
kubectl exec $POD_NMAE env
To display custom columns
kubectl get pod -o=custom-columns=NODE:.spec.nodeName,NAME:.metadata.name,podIP:.status.podIP,NAMESPACE:.metadata.namespace --all-namespaces
kubectl config set-context --current --namespace="namespace name"
Dashboard
Reference file for dashboard.yaml https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml
Similar file, is present at Katacoda course
First, one need set few alias at .bashrc file.
alias k=kubectl
alias kg=kubectl get
alias m=minikube
Minikube
By default, minikube runs with 2 CPUs and 2GB RAM. It makes the system slow. minikube needs minimum 2 CPU. With trial and error i found, 1.5 GB is sufficient to run minikube.
minikube start --memory 1536
Now few commands
kubectl config view
kubectl cluster-info
kubectl get nodes
kubectl desscribe node
minikube ip
minikube dashboard
minikube addons enable heapster
minikube addons list
minikube service list
minikube status
Service related commands
One can use svc in place of service for kubectl command, not for minikube commands
kubectl get svc
command lists services only from default namespace, while
minikube service list
command list services from all namespace.
One can add "-n kube-system" for kubectl command.
kubectl get svc -n kube-system
One can also add "--all-namespaces" for kubectl command
kubectl get svc --all-namespaces
Virtual Box
/home folder of host OS is mounted as /hosthome folder inside VirtualBox
To login to virtual box
minikube ssh
OR
ssh to minikube's IP address with docker/tcuser
Note: None of the above methods work at Katacoda for first scenario "Launching single Node cluster" under "Introduction to Kubernets" hands-on.
Here are comparision of IP address and various interface within virtual box and outside virtual box
| IP Address | Interface | Interface | IP Address | Remarks |
|---|---|---|---|---|
| Outside VBox | Outside VBox | Inside VBox | Inside VBox | |
| 172.17.0.1 | docker0 | docker0 | 172.17.0.1 | Pod network |
| 192.168.99.1 | vboxnet0 | eth1 | 192.168.99.102 | Minikube IP address |
| eth0 | 10.0.2.15 | Node Internal IP | ||
| 127.0.0.1 | lo | lo | 127.0.0.1 | Local interface |
Deployment
I found, below 3 basic images to begin with
kubectl create deployment x --image=katacoda/docker-http-server
kubectl create deployment k --image=k8s.gcr.io/echoserver:1.10
kubectl create deployment i --image=nginx
The dployment should be exposed with below commans
For http-server and nginx
kubectl expose deployment x
For echo-server
kubectl expose deployment k
kubectl delete svc
kubectl delete deployment
As per katacoda, the service can be tested with curl command as below
export PORT=$(kubectl get svc first-deployment -o go-template='{{range.spec.ports}}{{if .nodePort}}{{.nodePort}}{{"\n"}}{{end}}{{end}}')
echo "Accessing host01:$PORT"
curl host01:$PORT
There are alternate ways also
2.
curl $(minikube service x --url)
3. The below command invoke browser with required URL
minikube service x
4. Using proxy
kubectl proxy
Open URL in browser
http://127.0.0.1:8001/api/v1/namespaces/default/pods/POD_NAME/proxy/
POD
To get details about pod in JSON format
1.
kubectl get pods
2.
kubectl proxy
Open URL in browser
http://127.0.0.1:8001/api/v1/namespaces/default/pods/
To login to pod
kubectl exec -it $POD_NAME bash
To get enviornment variables
kubectl exec $POD_NMAE env
To display custom columns
kubectl get pod -o=custom-columns=NODE:.spec.nodeName,NAME:.metadata.name,podIP:.status.podIP,NAMESPACE:.metadata.namespace --all-namespaces
kubectl config set-context --current --namespace="namespace name"
Dashboard
Reference file for dashboard.yaml https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml
Similar file, is present at Katacoda course
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