Kubernetes notes

gistfile1.txt

Kubernetes Deployments
- Minikube disto for kuberntes deployment (locally Linux Mac and Windows) (recommended for development and learning) use cloud for production
- Deployments are high level constructs that define an application
- Pods are instances of a container in a deployment
- Services are the endpoints that export ports to the outside world

Text Lecture: Minikube Setup
Commands
* Linux: 
*  
* curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
*  
* MacOS: 
*  
* curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/darwin/amd64/kubectl
*  
* Windows: 
*  
* curl -LO https://storage.googleapis.com/kubernetes-release/release/v1.8.0/bin/windows/amd64/kubectl.exe
*  
* chmod +x ./kubectl
* sudo mv ./kubectl /usr/local/bin/kubectl
* kubectl version
*  
* Linux: 
*  
* curl -Lo minikube https://storage.googleapis.com/minikube/releases/v0.23.0/minikube-linux-amd64 && chmod +x minikube && sudo mv minikube /usr/local/bin/
*  
* macOS: 
*  
* curl -Lo minikube https://storage.googleapis.com/minikube/releases/v0.23.0/minikube-darwin-amd64 && chmod +x 
* minikube && sudo mv minikube /usr/local/bin/
* minikube start
* kubectl run hello-minikube --image=gcr.io/google_containers/echoserver:1.4 --port=8080
* kubectl expose deployment hello-minikube  --type=NodePort
* kubectl get pod
* curl $(minikube service hello-minikube --url)
* kubectl delete deployment hello-minikube
* minikube stop


Trouble Shooting
Error 1
* [root@larry ~]# minikube start
* Starting local Kubernetes v1.10.0 cluster...
* Starting VM...
* E0726 16:03:16.856132 3753 start.go:168] Error starting host: Error creating host: Error executing step: Running precreate checks.
* : This computer doesn't have VT-X/AMD-v enabled. Enabling it in the BIOS is mandatory.
*  
* Retrying.
* E0726 16:03:16.856723 3753 start.go:174] Error starting host: Error creating host: Error executing step: Running precreate checks.
* : This computer doesn't have VT-X/AMD-v enabled. Enabling it in the BIOS is mandatory
Solution:
Run minikube start --vm-driver=none instead
Related Q&A:
https://www.udemy.com/kubernetes-from-a-devops-kubernetes-guru/learn/v4/questions/4793372


Error 2
* root@localhost ~]# minikube start
* Starting local Kubernetes v1.10.0 cluster...
* Starting VM...
* E0504 17:44:35.629203    9741 start.go:159] Error starting host: Error creating host: Error executing step: Running precreate checks.
* : VBoxManage not found. Make sure VirtualBox is installed and VBoxManage is in the path.
*  Retrying.
* E0504 17:44:35.630354    9741 start.go:165] Error starting host:  Error creating host: Error executing step: Running precreate checks.
* : VBoxManage not found. Make sure VirtualBox is installed and VBoxManage is in the path
Solution:
On Linux machines you do not need to use any VM Driver.
Run below command instead.
* ./minikube start --vm-driver=none
If you are not running Linux machines, Install VirtualBox on the VM.
Related Q&A:
https://www.udemy.com/kubernetes-from-a-devops-kubernetes-guru/learn/v4/questions/4207802
https://www.udemy.com/kubernetes-from-a-devops-kubernetes-guru/learn/v4/questions/



Kubelet is a supervisor for kubernetes processes -> manage nodes on on process
Kubeproxy -> handles network services like connecting app at port 80 is handled by kubeproxy





Cluster commands
1. kubectl run gateway --image=gcr.io/thesocialapp/gateway:latest --port=3000
2. Kubectl get deployment
3. Kubectl get pods
4. Kubectl expose deployment gateway —type=“LoadBalancer” —port=5000 to expose the service
5. Kubectl get services gateway
6. Kubectl scale deployment gateway —replicas=4
7. Kubectl get deployment

Getting clusters list and setting the default  cluster for operation
- Creating a cluster
gcloud container clusters create [CLUSTER_NAME]
- Get the authentication credentials for the created cluster
gcloud container clusters get-credentials [CLUSTER_NAME]

Kubectl commands to run the Kubectl process (https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#run)
 run NAME --image=image [--env="key=value"] [--port=port] [--replicas=replicas] [--dry-run=bool] [--overrides=inline-json] [--command] -- [COMMAND] [args...]

- Running the Kubectl process
kubectl run hello-server --image gcr.io/google-samples/hello-app:1.0 --port 8080 
mention the port number that a process is exposing
- Exposing the deployment
kubectl expose deployment hello-server --type LoadBalancer --port 80 --target-port 8080
Here type is the deployment expose type. You can find more details about it here. (https://stackoverflow.com/a/41510604/2445898)
- Getting a specific cluster details
kubectl get service hello-server

- Connecting with the pod shell
kubectl exec -it [YOUR_POD_NAME] -- sh
- 

gcloud config set container/cluster [CLUSTER_NAME]


Switching across clusters

1. Kubectl config view
2. Kubectl config current-context
3. Kubectl config use-context [cluster-name]

To see the pods logs
1. Kubectl get pods ——> will give the list of the pods running under the current-context
2. Kubectl logs [pod-name] ——> will give the console log of the requested pod.


gcloud container clusters get-credentials NAME [--internal-ip] [--region=REGION    | --zone=ZONE, -z ZONE] [GCLOUD_WIDE_FLAG …]