Diskussion:Minikube

Hello Minikube

This tutorial shows you how to run a sample app on Kubernetes using minikube. The tutorial provides a container image that uses Nginx to echo back all the requests.

Objectives

• Deploy a sample application to minikube.
• Run the app.
• View application logs.

Before you begin

This tutorial assumes that you have already set up minikube. See Step 1 in minikube start for installation instructions.

Note

Only execute the instructions in Step 1, Installation. The rest is covered on this page.

You also need to install kubectl. See Install tools for installation instructions.

Create a minikube cluster

minikube start

Open the Dashboard

Open the Kubernetes dashboard. You can do this two different ways:

• Launch a browser
• URL copy and paste

Launch a browser

Open a new terminal, and run:

# Start a new terminal, and leave this running.
minikube dashboard

Now, switch back to the terminal where you ran minikube start.

Note

The dashboard command enables the dashboard add-on and opens the proxy in the default web browser. You can create Kubernetes resources on the dashboard such as Deployment and Service.

To find out how to avoid directly invoking the browser from the terminal and get a URL for the web dashboard, see the "URL copy and paste" tab.

By default, the dashboard is only accessible from within the internal Kubernetes virtual network. The dashboard command creates a temporary proxy to make the dashboard accessible from outside the Kubernetes virtual network.

To stop the proxy, run Ctrl+C to exit the process. After the command exits, the dashboard remains running in the Kubernetes cluster. You can run the dashboard command again to create another proxy to access the dashboard.

URL copy and paste

If you don't want minikube to open a web browser for you, run the dashboard subcommand with the --url flag. minikube outputs a URL that you can open in the browser you prefer.

Open a new terminal, and run:

# Start a new terminal, and leave this running.
minikube dashboard --url

Now, you can use this URL and switch back to the terminal where you ran

minikube start

Create a Deployment

A Kubernetes Pod is a group of one or more Containers, tied together for the purposes of administration and networking. The Pod in this tutorial has only one Container. A Kubernetes Deployment checks on the health of your Pod and restarts the Pod's Container if it terminates. Deployments are the recommended way to manage the creation and scaling of Pods.

kubectl create

Use the kubectl create command to create a Deployment that manages a Pod. The Pod runs a Container based on the provided Docker image.

# Run a test container image that includes a webserver</nowiki>
kubectl create deployment hello-node --image=registry.k8s.io/e2e-test-images/agnhost:2.39 -- /agnhost netexec --http-port=8080

View the Deployment

kubectl get deployments

The output is similar to

NAME     READY  UP-TO-DATE  AVAILABLE  AGE
hello-node  1/1   1      1      1m

(It may take some time for the pod to become available. If you see "0/1", try again in a few seconds.)

View the Pod

kubectl get pods

The output is similar to NAME READY STATUS RESTARTS AGE >hello-node-5f76cf6ccf-br9b5 1/1 Running 0 1m

View cluster events

kubectl get events

View the kubectl configuration

kubectl config view

1. View application logs for a container in a pod (replace pod name with the one you got from kubectl get pods).

Note

Replace hello-node-5f76cf6ccf-br9b5 in the kubectl logs command with the name of the pod from the kubectl get pods command output.

kubectl logs hello-node-5f76cf6ccf-br9b5

The output is similar to

I0911 09:19:26.677397    1 log.go:195] Started HTTP server on port 8080
I0911 09:19:26.677586    1 log.go:195] Started UDP server on port 8081

Note

For more information about kubectl commands, see the kubectl overview.

Create a Service

By default, the Pod is only accessible by its internal IP address within the Kubernetes cluster. To make the hello-node Container accessible from outside the Kubernetes virtual network, you have to expose the Pod as a Kubernetes Service.

Warning

The agnhost container has a /shell endpoint, which is useful for debugging, but dangerous to expose to the public internet. Do not run this on an internet-facing cluster, or a production cluster.

Expose the Pod to the public internet using the kubectl expose command

kubectl expose deployment hello-node --type=LoadBalancer --port=8080

The --type=LoadBalancer flag indicates that you want to expose your Service outside of the cluster.

The application code inside the test image only listens on TCP port 8080. If you used kubectl expose to expose a different port, clients could not connect to that other port.

View the Service you created

kubectl get services

The output is similar to

NAME     TYPE      CLUSTER-IP   EXTERNAL-IP  PORT(S)     AGE
hello-node  LoadBalancer  10.108.144.78  <pending>   8080:30369/TCP  21s
kubernetes  ClusterIP   10.96.0.1    <none>    443/TCP     23

On cloud providers that support load balancers, an external IP address would be provisioned to access the Service. On minikube, the LoadBalancer type makes the Service accessible through the minikube service command.

Run the following command

minikube service hello-node
This opens up a browser window that serves your app and shows the app's response.

Enable addons

The minikube tool includes a set of built-in addons that can be enabled, disabled and opened in the local Kubernetes environment.

List the currently supported addons

minikube addons list

The output is similar to:

addon-manager: enabled
dashboard: enabled
default-storageclass: enabled
efk: disabled
freshpod: disabled
gvisor: disabled
helm-tiller: disabled
ingress: disabled
ingress-dns: disabled
logviewer: disabled
metrics-server: disabled
nvidia-driver-installer: disabled
nvidia-gpu-device-plugin: disabled
registry: disabled
registry-creds: disabled
storage-provisioner: enabled
storage-provisioner-gluster: disabled

1. Enable an addon, for example, metrics-server:

minikube addons enable metrics-server

The output is similar to:

The 'metrics-server' addon is enabled

View the Pod and Service you created by installing that addon

kubectl get pod,svc -n kube-system

The output is similar to

NAME                    READY   STATUS  RESTARTS  AGE
pod/coredns-5644d7b6d9-mh9ll        1/1    Running  0     34m
pod/coredns-5644d7b6d9-pqd2t        1/1    Running  0     34m
pod/metrics-server-67fb648c5        1/1    Running  0     26s
pod/etcd-minikube              1/1    Running  0     34m
pod/influxdb-grafana-b29w8         2/2    Running  0     26s
pod/kube-addon-manager-minikube       1/1    Running  0     34m
pod/kube-apiserver-minikube         1/1    Running  0     34m
pod/kube-controller-manager-minikube    1/1    Running  0     34m
pod/kube-proxy-rnlps            1/1    Running  0     34m
pod/kube-scheduler-minikube         1/1    Running  0     34m
pod/storage-provisioner           1/1    Running  0     34m

NAME              TYPE    CLUSTER-IP   EXTERNAL-IP  PORT(S)       AGE
service/metrics-server     ClusterIP  10.96.241.45  <none>    80/TCP       26s
service/kube-dns        ClusterIP  10.96.0.10   <none>    53/UDP,53/TCP    34m
service/monitoring-grafana   NodePort  10.99.24.54   <none>    80:30002/TCP    26s
service/monitoring-influxdb  ClusterIP  10.111.169.94  <none>    8083/TCP,8086/TCP  26s

Check the output from metrics-server

kubectl top pods

The output is similar to:

NAME             CPU(cores)  MEMORY(bytes)  
hello-node-ccf4b9788-4jn97  1m      6Mi       

If you see the following message, wait, and try again:

error: Metrics API not available

Disable metrics-server

minikube addons disable metrics-server

The output is similar to

metrics-server was successfully disabled

Clean up

Now you can clean up the resources you created in your cluster:

kubectl delete service hello-node
kubectl delete deployment hello-node

Stop the Minikube cluster

minikube stop

Optionally, delete the Minikube VM:

Optional

minikube delete

If you want to use minikube again to learn more about Kubernetes, you don't need to delete it.

Conclusion

This page covered the basic aspects to get a minikube cluster up and running. You are now ready to deploy applications.

What's next

• Tutorial to deploy your first app on Kubernetes with kubectl.
• Learn more about Deployment objects.
• Learn more about Deploying applications.
• Learn more about Service objects.

Quelle

https://kubernetes.io/docs/tutorials/hello-minikube/