Before reading this article, please refer to
1. Kubernetes deploys "containerized applications" (testing kubernetes clusters)
1. Containerized application
In layman's terms, it is to deploy a program in Docker, and this Docker application is a containerized application.
For example: Deploying a SpringBoot in Docker, this Docker+SpringBoot together is a containerized application
The core idea of Docker is how to integrate applications into containers and actually run them in containers.
The process of integrating applications into containers and running them is called "Containerizing" (Containerizing), sometimes also called "Dockerizing" (Dockerizing).
Containers are born for applications. Specifically, containers can simplify the process of building, deploying, and running applications.
2. Docker deployment application
(1) Write application code
(2) Create a Dockerfile that includes a description of the current application, dependencies, and how to run the application
(3) Execute the docker image build command on the Dockerfile
(4) Wait for Docker to build the application into the Docker image
Once the application is containerized (that is, the application is packaged as a Docker image), it can be delivered as an image and run as a container
3. k8s deployment application
(1) Write application code
(2) Create a Dockerfile that includes a description of the current application, dependencies, and how to run the application
(3) Mirror the application through K8S
1. Deploy an Nginx in the Kubernetes cluster
1. Pull an nginx mirror on the Internet
kubectl create deployment nginx --image=nginx2. Expose a port 80 to the outside world
kubectl expose deployment nginx --port=80 --type=NodePort3. Check the external port
kubectl get pod,svc4. Access address: http://NodeIP:Port
2. Deploy a Tomcat in the Kubernetes cluster
kubectl create deployment tomcat --image=tomcat
kubectl expose deployment tomcat --port=8080 --type=NodePort
kubectl get pod,svcAccess address: http://NodeIP:Port
kubectl get related commands
// Get node and service version information
kubectl get node(s)
// All services in all namespaces
kubectl get service(s)
// list deployments
kubectl get deployment (deploy)
// List all pods in all namespaces
kubectl get pod(s)
//delete service
kubectl delete service nginx
//Delete nginx controller
kubectl delete deployment nginx
//delete pod
kubectl delete pod nginx-6799fc88d8-zc48m (pod name)
//kubectl command help
kubectl --help
3. Kubernetes cluster deployment SpringBoot application
1. Write the application, pack it into jar or war, and upload it to Linux (for example, the blogger put it in the /opt/app/k8s path)
2. Write a Dockerfile file to customize the JDK image
(1) Dockerfile
FROM java:8
MAINTAINER zm
EXPOSE 8081
ADD springboot-1-hello.jar springboot-1-hello.jar
# Dockerfile时区设置
RUN echo 'Asia/Shanghai' >/etc/timezone
ENTRYPOINT ["java","-jar","springboot-1-hello.jar"](2) Build and run the image; write scripts here
Note:
After Windows writes a script and uploads it to Linux, an error will be reported: xx.sh: line 2: $'\r': command not found , the solution is described in the following stepping pit module, please refer to
#!/bin/sh
cd /opt/app/k8s
docker rm -f springboot-1-hello
docker rmi springboot-1-hello:latest
docker build -t springboot-1-hello .
docker run -d -p 8081:8081 -e "SPRING_PROFILES_ACTIVE=test" -v /etc/localtime:/etc/localtime -v /data/logs/app/springboot-1-hello:/logs -v /data/files/app/springboot-1-hello:/files -v /etc/hosts:/etc/hosts -v /etc/hostname:/etc/hostname --restart=always --privileged=true --name springboot-1-hello springboot-1-hello:latest3. docker images view image
Note:
This image needs to be deployed on the master master node machine and all node slave node machines, otherwise an error ErrImageNeverPull will be reported ! ! !
Container image "springboot-1-hello" is not present with pull policy of Never
Error: ErrImageNeverPull4. Run the test dry to generate a yaml or json file
// kubectl get deployment will not create a deployment; it will only output configuration content in yaml format
kubectl create deployment deployment name --image=custom project image name --dry-run -o yaml
// kubectl get deployment will not create a deployment; it will only output configuration content in json format
kubectl create deployment deployment name --image=custom project image name --dry-run -o json
// Only the configuration file of deploy.yaml will be generated
kubectl create deployment deployment name --image=custom project image name --dry-run -o yaml > yaml file to be generated
// Only the configuration file of deploy.json will be generated
kubectl create deployment deployment name --image=custom project image name --dry-run -o json > json file to be generated
--dry-run means dry run test, will not actually run
-o means test output
as follows:
kubectl create deployment springboot-k8s --image=springboot-1-hello --dry-run -o yaml
kubectl create deployment springboot-k8s --image=springboot-1-hello --dry-run -o json
kubectl create deployment springboot-k8s --image=springboot-1-hello --dry-run -o yaml > deploy.yaml
或者
kubectl create deployment springboot-k8s --image=springboot-1-hello --dry-run -o json> deploy.json
The content of the deploy.yaml or deploy.json file we generated (in the same directory as the jar package) is consistent with the content of the direct output (you can also manually create the file to write the content)
Viewed through the kubectl get deploy command, the deployment is not really running
5. Deployment
Note:
The image in the deploy.yaml file needs to be pulled from the local, otherwise an error will be reported and the failure to pull the local image will be reported (the kubernetes ( K8S) cluster cannot normally pull the image file in the self-built image warehouse, the default is to pull the image from the central warehouse )
Failed to pull image "springboot-1-hello": rpc error: code = Unknown desc = Error response from daemon: pull access denied for springboot-1-hello, repository does not exist or may require 'docker login': denied: requested access to the resource is denied
Normal BackOff 47m (x7 over 50m) kubelet Back-off pulling image "springboot-1-hello"
Warning Failed 25m (x9 over 50m) kubelet Error: ErrImagePull
Warning Failed 62s (x191 over 50m) kubelet Error: ImagePullBackOff//检查是否创建了deployments任务
kubectl get deployments
kubectl get pods
//查看pod详细信息
kubectl describe pods pod名称
//查看pod日志
kubectl logs pod名称
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 91s default-scheduler Successfully assigned default/springboot-k8s-648db45cd5-42f2j to k8snode
Warning ErrImageNeverPull 11s (x8 over 89s) kubelet Container image "springboot-1-hello" is not present with pull policy of Never
Warning Failed 11s (x8 over 89s) kubelet Error: ErrImageNeverPullModify the deploy.yaml file, and change the image pull policy imagePullPolicy to Never (the image is pulled from the local, and the default is to pull the image from the central warehouse)
spec:
containers:
- image: springboot-1-hello
name: springboot-1-hello
imagePullPolicy: Never
The usage of imagePullPolicy is summarized as follows
| name strategy | effect |
|---|---|
| Never | Only use local images |
| Always | download mirror every time |
| IfNotPresent | The local image is used first, and there is no need to download it locally |
Re-execute the kubectl apply -f deploy.yaml command
//Check if the deployments task is created: kubectl get deployments
kubectl get pods
//View pod details: kubectl describe pods pod name
//View pod logs: kubectl logs pod name
Error from server (BadRequest): container "springboot-1-hello" in pod "springboot-k8s-648db45cd5-42f2j" is waiting to start: ErrImageNeverPull
Note:
Kubernetes (K8S) cluster deployment with one master and multiple slaves
In order to use local mirroring in this mode, two conditions need to be met:
1. ImagePullPolicy is set to IfNotPresent (if not locally, it will be pulled from the remote warehouse) or Never (only pulled from the local)
2. The slave node must have this image. To be precise, which node is scheduled, the image must exist on that node, otherwise ErrImageNeverPull will be reported
(1) Yml file deployment
kubectl apply -f deploy.yaml (yaml是资源清单)
等价于
kubectl create deployment springboot-k8s --image=springboot-1-helloExpose the service port:
kubectl expose deployment springboot-k8s --port=8081 --type=NodePortAt this point you can view the service: kubectl get service
(2) Command mode deployment
kubectl create deployment springboot-k8s --image=springboot-1-helloEnter the following address in the browser to access, both master and slave node IPs are available
http://192.168.133.129:8081/springboot-1-hello/hellospringboot
Two, step on the pit
1. K8S executes kubectl xx xx and reports Unable to connect to the server: net/http: TLS handshake timeout
https://blog.csdn.net/MinggeQingchun/article/details/126423450
When executing the kubectl get nodes command to view the Node node, it took 3 to 5 minutes to return the result, and an error was reported. The error message is as follows:
Unable to connect to the server: net/http: TLS handshake timeoutIt may be that the memory allocation of the VM virtual machine is too small, or the memory of the master node is too small, because the swap partition is turned off
Therefore, increase the memory of the VM virtual machine from 2G to 4G, restart the virtual machine, and execute kubectl get nodes.
2. xx.sh: line 2: $'\r': command not found (Windows writes Docker to run the script to start the container)
https://blog.csdn.net/MinggeQingchun/article/details/126422635
When we write a script on the Windows system and upload it to Linux, an error will be reported when the script is executed
xx.sh: line 2: $'\r': command not foundUbuntu workaround:
1、sudo apt-get install tofrodos
2. fromdos sh script file name
Centos solution:
1、yum -y install dos2unix
2. dos2unix sh script file name
3. Master node Ready; Node node NotReady
kubectl get nodes
master node host
Node node host
Check out the kubelet startup log
journalctl -f -u kubelet
From the last two logs, we can judge that the node node has stopped being proxied
The master startup sequence of k8s in the host is: systemd > kubelet > container components >
kubernetes
We can judge from systemd to kubelet, because kubelet is an application process, so we check the status of kubelet (master, node master and slave are all executed)
systemctl status kubeletWe can see from the command line that the kubelet is not loaded (node node slave)
So we use the command to restart and start the service to start it (node node slave)
systemctl restart kubelet
systemctl status kubelet
At this time, go to check the master node host
4. The SpringBoot application needs to deploy Docker images on the master and all Node node machines
The SpringBoot application needs to deploy the Docker image on the master and all Node node machines. If it is only deployed on the master master node, and the Node node machine is not deployed, otherwise an error ErrImageNeverPull will be reported ! ! !
Container image "springboot-1-hello" is not present with pull policy of Never
Error: ErrImageNeverPull
Kubernetes (K8S) cluster deployment with one master and multiple slaves
In order to use local mirroring in this mode, two conditions need to be met:
1. ImagePullPolicy is set to IfNotPresent (if not locally, it will be pulled from the remote warehouse) or Never (only pulled from the local)
2. The slave node must have this image. To be precise, which node is scheduled, the image must exist on that node, otherwise ErrImageNeverPull will be reported