Basic Introduction to kubernetes and Common Commands of kubectl
pod classification of k8s
There are two categories of pod s:
- Autonomous pod
- Controller managed pod
Autonomous pods are managed by k8s manager, while static pod s are created and managed by kubelet
Autonomous pod
Autonomous pods always run in the foreground and are managed and dispatched by k8s. When a pod in a cluster stops for some reason, k8s regenerates the corresponding pod based on the number of copies it has
A self-managed pod that still needs to be submitted to apiserver after it has been created, which is then dispatched to the specified node with the help of a dispatcher and initiated by the node
If this pod fails, restarting the container is done by kubelet
If the node fails, the pod will disappear. It cannot achieve global scheduling. So this pod is not recommended
Controller managed pod
Common pod controllers:
-
ReplicationController: When a pod is started. This pod can be re-enabled if it is not enough, and the controller will then manage the various copies and objects of the same type of pod. As soon as there are fewer copies, they increase automatically. Take the rule of more refunds and less supplements to meet exactly the expectations we define. Support for rolling updates
-
ReplicaSet: Managed by a declarative update controller called Deployment
-
Deployment:Deployment can only manage stateless applications
-
StateFulSet: Stateful replica set to manage stateful applications
-
DaemonSet: Use DaemonSet if you need to run a copy on each node
Core Primary Key
HPA
Deployment also supports secondary controllers, HPA(HorizontalPodAutoscaler, Horizontal Pod Autoscaler). Normally, we can make sure that there are two pods running on a node. In case user access traffic increases, what should we do if two pods are not enough to carry that amount of access? At this point we should increase the pod resources, how many should we add?
The HPA controller automatically monitors the pod and automatically expands it.
service
If there are two pods and the pod has its life cycle, in case the node where the pod is located is down, the pod should be rebuilt on other nodes. The rebuilt pod is not the same pod as the original pod, but both are running the same service. And each container has its own IP address. The IP address of the container in the reconstructed pod is different from that of the container in the previous pod. So there will be a problem, how can the client access the container in these pods? (will switch to another node to run)
For service discovery, a pod has a life cycle, a pod may leave at any time, and other internal pods may be added at any time. If they provide the same service, clients cannot access these pods by fixed means, because the pods themselves are not fixed, they may be replaced at any time, regardless of host name or IP address. Will always be replaced.
To minimize the complexity of client-to-pod coordination, k8s adds an intermediate layer between each group of pods that provide similar services and their clients, which is fixed and called a service.
As long as a service is not deleted, its address and name are fixed. When a client needs to write on its configuration file to access a service, it no longer needs to be discovered automatically. It just needs to write the name of the service in the configuration file. This service is a scheduler, which can provide a stable access entry and can also act as a reverse proxy. When a service receives a request from a client, it will be proxied over the back-end pod. Once the pod is down, a new pod will be created immediately. The new pod will be immediately associated with the service as one of the available pods on the back-end of the service.
Client programs access services through IP+port or hostname+port. The service associates the back-end pod not by its IP and host name, but by the pod's label selector. As long as the label of the pod created is uniform, it can be recognized by the service regardless of how the IP address and host change. This way, as long as the pod belongs to the tag selector and is within the scope of service management, it will be associated with the service. After the dynamic pod is associated with the service, it will dynamically detect the IP address and port of the pod, and then act as the available service King machine for its own backend to schedule. Therefore, the client's request is sent to the service and the service is proxied to the container in the back-end's real pod to respond.
Service is not a program or a component, it is just a dnat rule of iptables. As an object of k8s, service has its own name, which corresponds to the name of the service, which can be resolved.
AddOns Attachments
dns pod: The first thing you need to do after installing k8s is to deploy a dns pod on the k8s cluster to ensure that the name of each service can be dynamically changed by resolution, including dynamic creation, dynamic deletion, dynamic modification, such as changing the name of the service, dns pod triggers automatically, and the name in the dns resolution record is also changed. If we manually change the service's ip address, it will trigger automatically after the change, and the parsed records in the dns service will be removed. This allows clients to access pod resources directly by accessing the name of the service, which is then resolved by a dedicated dns service in the cluster.
This pod is a pod that k8s needs for its own services, so we call it an infrastructure-level pod object, and they are also called cluster attachments
network model
Three network models
- Node Network
- service cluster network
- pod network
Communication with Pod Node
Before the container starts, a virtual Ethernet interface pair is created for the container, which resembles two ends of a pipeline, one end in the host namespace and the other end in the container namespace, named eth0. The interface in the host namespace is bound to the bridge. The address segment of the bridge assigns IP to the eth0 interface of the container.
Pod communication on different nodes
We already know that containers on one node are connected to the same bridge, so to allow containers running on different nodes to communicate, the bridges of these nodes need to be connected in some way.
The IP addresses of PD across the entire cluster must be unique, and all cross-node bridges must use non-overlapping network address segments to prevent Pod s on different nodes from getting the same IP address, that is, to ensure that there are no IP address conflicts.
When sent to a container on B node, the message is first paired to the bridge through the veth interface, then the physical adapter from the bridge to A node, then transferred to the physical adapter of B node through the network cable, and then to the destination container through the interface pair through the bridge on B node.
Note: The above scenarios are only valid if the nodes are connected to the same gateway without any routing devices between them. Otherwise, the routing device will lose packets due to IP privacy unless routing rules are set. However, as the number of nodes increases, the routing configuration becomes very difficult. So we use SDN (Software Defined Network) technology to simplify such problems, and SDN can ignore the underlying network topology, making it feel like connecting to the same gateway.
Pod and Service
In Pod communication on different nodes, we know that Pod communicates with IP address, but in the cluster of Kubernetes, Pod may be destroyed and created frequently, that is, Pod's IP is not fixed.
To solve this problem, Service provides an abstraction layer for accessing Pods, which provides a single, constant access point resource for a set of functionally identical Pods.
Regardless of how the Pod of the back end changes, Service serves externally as a stable front end.
Service also provides high availability and load balancing, which forwards requests to the correct Pod.
Common commands for kubectl
grammar
kubectl [command] [TYPE] [NAME] [flags] command: Subcommand TYPE: Resource Type NAME: Resource Name flags: Command parameters Command Help kubectl The command's help is detailed. kubectl -h All subcommands are listed, followed by any subcommand -h，Both output detailed help and use cases, and you can always see the help if you encounter problems. Resource Object kubectl Most subcommands allow you to specify a resource object to operate on. You can use kubectl api-resources Command Reference Global parameters kubectl options Commands can list command parameters that can be used globally --cluster='': Specify the cluster of command action objects --context='': Specify the context of the command action object -n, --namespace='': Specify the command action object's Namespace
create
Create pod from file or standard output
# Create a pos of deployment type named nginx1 with a mirror image of nginx [root@master ~]# kubectl create deployment wb1 --image=nginx deployment.apps/wb1 created [root@master ~]# kubectl create deployment nginx1 --image=nginx deployment.apps/nginx1 created [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 40s # Create a pos of deployment type, named nginx2, using a mirror image of nginx, replicas is the number of specified creations [root@master ~]# kubectl create deployment nginx2 --image=nginx --replicas=2 deployment.apps/nginx2 created [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 3m2s nginx2-85bf7b8976-68q5d 0/1 ContainerCreating 0 42s nginx2-85bf7b8976-74l6z 1/1 Running 0 42s
run
Run a specified mirrored pod (autonomous pod) in the cluster
# The pod running with run defaults to the pod type [root@master ~]# kubectl run nginx --image nginx pod/nginx created [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx 0/1 ContainerCreating 0 11s # Run a pod called nginx1, using a mirror nginx, specifying the label app=web [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx 0/1 ContainerCreating 0 11s wb1-5dbfb96758-hhfhb 1/1 Running 0 16m [root@master ~]# kubectl run nginx1 --image=nginx --labels="app=web" pod/nginx1 created [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx 1/1 Running 0 2m9s nginx1 1/1 Running 0 18s # Create a few more so that their labels are nginx [root@master ~]# kubectl run nginx2 --image=nginx --labels="app=web" pod/nginx2 created [root@master ~]# kubectl run nginx3 --image=nginx --labels="app=web" pod/nginx3 created #Check it out [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx 1/1 Running 0 5m49s nginx1 1/1 Running 0 3m58s nginx2 1/1 Running 0 73s nginx3 1/1 Running 0 43s # Specifying a label when deleting deletes the pod of the corresponding label [root@master ~]# kubectl delete pod -l app=web pod "nginx1" deleted pod "nginx2" deleted pod "nginx3" deleted #Trial run, does not really create run, can specify client/server end run [root@master ~]# kubectl run web123 --image=nginx --dry-run=client pod/web123 created (dry run) # Start a pod and put it in the foreground. If it exits, do not restart it [root@master ~]# kubectl run -i -t web123 --image=busybox --restart=Never If you don't see a command prompt, try pressing enter. / # ls -l total 16 drwxr-xr-x 2 root root 12288 Dec 7 00:20 bin drwxr-xr-x 5 root root 380 Dec 19 10:22 dev drwxr-xr-x 1 root root 66 Dec 19 10:22 etc drwxr-xr-x 2 nobody nobody 6 Dec 7 00:20 home dr-xr-xr-x 219 root root 0 Dec 19 10:22 proc drwx------ 1 root root 26 Dec 19 10:22 root dr-xr-xr-x 13 root root 0 Dec 19 10:21 sys drwxrwxrwt 2 root root 6 Dec 7 00:20 tmp drwxr-xr-x 3 root root 18 Dec 7 00:20 usr drwxr-xr-x 1 root root 17 Dec 19 10:22 var
delete
Delete a resource's file name, standard output, resource and name, or resource and label selector
##View existing service s and pod s [root@master ~]# kubectl get pods,svc NAME READY STATUS RESTARTS AGE pod/nginx-85b98978db-dgkbp 1/1 Running 0 97m pod/nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 11m pod/nginx2-85bf7b8976-68q5d 1/1 Running 0 9m8s pod/nginx2-85bf7b8976-74l6z 1/1 Running 0 9m8s pod/nginx3-59475d8756-l8mcq 1/1 Running 0 7m17s pod/wb1-5dbfb96758-hhfhb 1/1 Running 0 11m NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 144m service/nginx NodePort 10.105.224.204 <none> 80:31753/TCP 97m #Delete service and pod named nginx [root@master ~]# kubectl delete deployment,svc nginx deployment.apps "nginx" deleted service "nginx" deleted #View after deletion [root@master ~]# kubectl get pods,svc NAME READY STATUS RESTARTS AGE pod/nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 13m pod/nginx2-85bf7b8976-68q5d 1/1 Running 0 10m pod/nginx2-85bf7b8976-74l6z 1/1 Running 0 10m pod/nginx3-59475d8756-l8mcq 1/1 Running 0 8m50s pod/wb1-5dbfb96758-hhfhb 1/1 Running 0 13m NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 146m
get
Show one or more resources
# View pod s created [root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-85b98978db-dgkbp 1/1 Running 0 90m nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 5m2s nginx2-85bf7b8976-68q5d 1/1 Running 0 2m42s nginx2-85bf7b8976-74l6z 1/1 Running 0 2m42s nginx3-59475d8756-l8mcq 1/1 Running 0 51s wb1-5dbfb96758-hhfhb 1/1 Running 0 5m14s # View pod s created [root@master ~]# kubectl get service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 138m nginx NodePort 10.105.224.204 <none> 80:31753/TCP 91m # View multiple messages separated by',' [root@master ~]# kubectl get service,pod NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 138m service/nginx NodePort 10.105.224.204 <none> 80:31753/TCP 91m NAME READY STATUS RESTARTS AGE pod/nginx-85b98978db-dgkbp 1/1 Running 0 91m pod/nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 5m52s pod/nginx2-85bf7b8976-68q5d 1/1 Running 0 3m32s pod/nginx2-85bf7b8976-74l6z 1/1 Running 0 3m32s pod/nginx3-59475d8756-l8mcq 1/1 Running 0 101s pod/wb1-5dbfb96758-hhfhb 1/1 Running 0 6m4s # View Namespace [root@master ~]# kubectl get ns NAME STATUS AGE default Active 139m kube-node-lease Active 139m kube-public Active 139m kube-system Active 139m # View pod of specified type [root@master ~]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE nginx 1/1 1 1 93m nginx1 1/1 1 1 7m49s nginx2 2/2 2 2 5m29s nginx3 1/1 1 1 3m38s wb1 1/1 1 1 8m1s [root@master ~]# kubectl get deployment nginx NAME READY UP-TO-DATE AVAILABLE AGE nginx 1/1 1 1 94m
expose
Expose port number, - target-port means expose target port number
Create a service that connects to it at port 80 with container 8000 and accesses 8000 in container with external 80
#Map 80 to 8000 because its type is ClusterIP, which means this service can only be accessed in a cluster; NodePort means it is accessible on the real machine [root@master ~]# kubectl expose deployment myapp --port 80 --target-port 8000 service/myapp exposed [root@master ~]# kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE myapp ClusterIP 10.110.171.169 <none> 80/TCP 3s nginx NodePort 10.111.4.86 <none> 80:30859/TCP 41h
edit
Edit resources defined on the server using the default editor
[root@master ~]# kubectl describe pod nginx
Name: nginx
Namespace: default
Priority: 0
Node: node1.example.com/192.168.235.172
Start Time: Mon, 20 Dec 2021 22:14:38 +0800
Labels: app=nginx
································
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 87s
...
labels:
app: test //Change the original nginx to test
name: nginx
[root@master ~]# kubectl describe pod nginx
...
Labels: app=test
scale
Expand or shrink the number of Pod s in Deployment, ReplicaSet, Replication Controller, or Job
Set the number of pod copies in nginx to 3
[root@master ~]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE nginx 1/1 1 1 8m30s [root@master ~]# kubectl scale --replicas 3 deployment/nginx deployment.apps/nginx scaled [root@master ~]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE nginx 1/3 3 1 8m56s [root@master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-6799fc88d8-5tsjt 1/1 Running 0 16s nginx-6799fc88d8-dwrsh 1/1 Running 0 9m5s nginx-6799fc88d8-sn82p 1/1 Running 0 15s // Current number of copies is 3, then expand to 5 root@master ~]# kubectl scale --current-replicas 3 --replicas 5 deployment/nginx deployment.apps/nginx scaled [root@master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-6799fc88d8-5tsjt 1/1 Running 0 62s nginx-6799fc88d8-dwrsh 1/1 Running 0 9m51s nginx-6799fc88d8-jkmln 0/1 ContainerCreating 0 2s nginx-6799fc88d8-qm5ld 0/1 ContainerCreating 0 2s nginx-6799fc88d8-sn82p 1/1 Running 0 61s [root@master ~]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE nginx 4/5 5 4 9m58s
autoscale
Automatically expands, given a range, to automatically increase or decrease access to the business
Set the number of copies of nginx deployment to be at least 1 and at most 5
[root@master ~]# kubectl autoscale --min 1 --max 5 deployment/nginx horizontalpodautoscaler.autoscaling/nginx autoscaled [root@master ~]# kubectl get hpa NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE nginx Deployment/nginx <unknown>/80% 1 5 0 8s
cluster-info
The display label is kubernetes.io/cluster-service=true's control plane and address of the service. To further debug and diagnose cluster problems, use "kubectl cluster-info dump"
[root@master ~]# kubectl cluster-info Kubernetes control plane is running at https://192.168.235.179:6443 KubeDNS is running at https://192.168.235.179:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
describe
View details of a specific resource or resource group
//View details of a pod named nginx
[root@master ~]# kubectl describe pod nginx
Name: nginx-6799fc88d8-5tsjt
Namespace: default
Priority: 0
Node: node1.example.com/192.168.235.172
Start Time: Mon, 20 Dec 2021 22:23:28 +0800
Labels: app=nginx
pod-template-hash=6799fc88d8
Annotations: <none>
Status: Running
IP: 10.244.1.5
IPs:
IP: 10.244.1.5
Controlled By: ReplicaSet/nginx-6799fc88d8
Containers:
nginx:
Container ID: docker://5a331ad8c751b41bfa7fd98f4f73e1c97cbc9f8aa76aada48f0be3fe22c10097
Image: nginx
Image ID: docker-pullable://nginx@sha256:9522864dd661dcadfd9958f9e0de192a1fdda2c162a35668ab6ac42b465f0603
Port: <none>
Host Port: <none>
State: Running
Started: Mon, 20 Dec 2021 22:23:37 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-n67dr (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-n67dr:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-n67dr
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 8m9s default-scheduler Successfully assigned default/nginx-6799fc88d8-5tsjt to node1.example.com
Normal Pulling 8m8s kubelet Pulling image "nginx"
Normal Pulled 8m kubelet Successfully pulled image "nginx" in 7.583042375s
Normal Created 8m kubelet Created container nginx
Normal Started 8m kubelet Started container nginx
logs
Output pod or log of containers in specified resources. If there is only one container in the pod, the container name is optional
// View nginx's log [root@master ~]# kubectl logs deployment/nginx Found 5 pods, using pod/nginx-6799fc88d8-dwrsh /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/ /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh 10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf 10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh /docker-entrypoint.sh: Configuration complete; ready for start up 2021/12/20 14:14:43 [notice] 1#1: using the "epoll" event method 2021/12/20 14:14:43 [notice] 1#1: nginx/1.21.4 2021/12/20 14:14:43 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6) 2021/12/20 14:14:43 [notice] 1#1: OS: Linux 4.18.0-257.el8.x86_64 2021/12/20 14:14:43 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576 2021/12/20 14:14:43 [notice] 1#1: start worker processes 2021/12/20 14:14:43 [notice] 1#1: start worker process 32 2021/12/20 14:14:43 [notice] 1#1: start worker process 33
attach
Connect to a running container
//Get the output of the running pod nginx and connect to the first container in the pod by default [root@master ~]# kubectl attach nginx Defaulting container name to nginx. Use 'kubectl describe pod/nginx -n default' to see all of the containers in this pod. If you don't see a command prompt, try pressing enter.
exec
Execute commands in containers
//Run date in the first container of pod/nginx by default and print out [root@master ~]# kubectl exec deployment/nginx date kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead. Mon Dec 20 14:38:25 UTC 2021
port-forward
Forward one or more local ports to pod
/Map the 80 ports in the container to the native port
[root@master ~]# kubectl port-forward nginx-6799fc88d8-5tsjt :80
Forwarding from 127.0.0.1:46459 -> 80
Forwarding from [::1]:46459 -> 80
[root@master ~]# curl 127.0.0.1:46459
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
[root@master ~]#
cp
Copy files and directories to or from containers
//Will be local anaconda-ks.cfg files transferred to pod/nginx/tmp directory [root@master ~]# kubectl cp anaconda-ks.cfg nginx-6799fc88d8-5tsjt:/tmp [root@master ~]# kubectl exec pod/nginx-6799fc88d8-5tsjt -- ls -l /tmp total 4 -rw------- 1 root root 1252 Dec 20 14:48 anaconda-ks.cfg
label
Update (add, modify, or delete) label s on resources.
- Labels must begin with a letter or number and can use letters, numbers, hyphens, dots, and underscores up to 63 characters.
- If -overwrite is true, you can overwrite the existing label, otherwise attempting to overwrite the label will result in an error.
- If -resource-version is specified, the update will use this resource version, otherwise the existing resource version will be used.
//Change label
[root@master ~]# kubectl describe deployment/nginx
Name: nginx
Namespace: default
CreationTimestamp: Mon, 20 Dec 2021 22:14:38 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision: 1
Selector: app=nginx
Replicas: 5 desired | 5 updated | 5 total | 5 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: app=nginx
Containers:
nginx:
Image: nginx
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Progressing True NewReplicaSetAvailable
Available True MinimumReplicasAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-6799fc88d8 (5/5 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 37m deployment-controller Scaled up replica set nginx-6799fc88d8 to 1
Normal ScalingReplicaSet 29m deployment-controller Scaled up replica set nginx-6799fc88d8 to 3
Normal ScalingReplicaSet 28m deployment-controller Scaled up replica set nginx-6799fc88d8 to 5
//Append Label
[root@master ~]# kubectl label deployment/nginx user=yaya
deployment.apps/nginx labeled
[root@master ~]# kubectl describe deployment/nginx
Name: nginx
Namespace: default
CreationTimestamp: Mon, 20 Dec 2021 22:14:38 +0800
Labels: app=nginx
user=tt
api-resources
Print supported API resources on the server
//View all resources [root@master ~]# kubectl api-resources NAME SHORTNAMES APIVERSION NAMESPACED KIND bindings v1 true Binding componentstatuses cs v1 false ComponentStatus configmaps cm v1 true ConfigMap
api-versions
Print the supported api version as a group/version on the server
[root@master ~]# kubectl api-versions admissionregistration.k8s.io/v1 admissionregistration.k8s.io/v1beta1 apiextensions.k8s.io/v1 apiextensions.k8s.io/v1beta1 apiregistration.k8s.io/v1 apiregistration.k8s.io/v1beta1 apps/v1 authentication.k8s.io/v1 authentication.k8s.io/v1beta1 authorization.k8s.io/v1 authorization.k8s.io/v1beta1 autoscaling/v1 autoscaling/v2beta1 autoscaling/v2beta2 batch/v1
k8s for rolling updates and rollbacks of versions
// Writing two mirrors with Dockerfile
//Make Mirror 1
[root@master ~]# mkdir httpd
[root@master ~]# cd httpd
[root@master httpd]# vim Dockerfile
[root@master httpd]# cat Dockerfile
FROM busybox
RUN mkdir /data && \
echo "test page on v1" > /data/index.html
ENTRYPOINT ["/bin/httpd","-f","-h","/data"]
[root@master httpd]# docker build -t weixiaoya/httpd:v0.1 .
Sending build context to Docker daemon 2.048kB
Step 1/3 : FROM busybox
latest: Pulling from library/busybox
3cb635b06aa2: Pull complete
Digest: sha256:b5cfd4befc119a590ca1a81d6bb0fa1fb19f1fbebd0397f25fae164abe1e8a6a
Status: Downloaded newer image for busybox:latest
---> ffe9d497c324
Step 2/3 : RUN mkdir /data && echo "test page on v1" > /data/index.html
---> Running in bf174265c61d
Removing intermediate container bf174265c61d
---> a074d85c6622
Step 3/3 : ENTRYPOINT ["/bin/httpd","-f","-h","/data"]
---> Running in e362ffafa0e2
Removing intermediate container e362ffafa0e2
---> 104d28f2d58c
Successfully built 104d28f2d58c
Successfully tagged weixiaoya/httpd:v0.1
//Make Mirror 2
[root@master httpd]# vim Dockerfile
[root@master httpd]# cat Dockerfile
FROM busybox
RUN mkdir /data && \
echo "test page on v2" > /data/index.html
ENTRYPOINT ["/bin/httpd","-f","-h","/data"]
[root@master httpd]# docker build -t weixiaoya/httpd:v2 .
Sending build context to Docker daemon 2.048kB
Step 1/3 : FROM busybox
---> ffe9d497c324
Step 2/3 : RUN mkdir /data && echo "test page on v2" > /data/index.html
---> Running in aa475f8038dd
Removing intermediate container aa475f8038dd
---> 867882b9f918
Step 3/3 : ENTRYPOINT ["/bin/httpd","-f","-h","/data"]
---> Running in 4cbc3af592c9
Removing intermediate container 4cbc3af592c9
---> e423298d601e
Successfully built e423298d601e
Successfully tagged weixiaoya/httpd:v2
[root@master httpd]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
weixiaoya/httpd v2 e423298d601e About a minute ago 1.24MB
weixiaoya/httpd v0.1 104d28f2d58c 3 minutes ago 1.24MB
busybox latest ffe9d497c324 13 days ago 1.24MB
[root@master ~]# docker push weixiaoya/httpd:v0.1
The push refers to repository [docker.io/weixiaoya/httpd]
0d4853dfdf52: Pushed
64cac9eaf0da: Mounted from library/busybox
v0.1: digest: sha256:fb79b8b64543613f2677aeb489451b329ed7b4ccbade1820d9d5205495107f4f size: 734
Based on httpd:v0 with k8s. 1 Mirror Run Mirror 3 pod s
[root@master ~]# kubectl create deploy httpd --image weixiaoya/httpd:v0.1 --replicas 3 deployment.apps/httpd created [root@master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE httpd-7649d9b878-5lvf7 1/1 Running 0 8m4s httpd-7649d9b878-ck6cq 1/1 Running 0 8m4s httpd-7649d9b878-pkqkk 1/1 Running 0 8m4s //Expose Port [root@master ~]# kubectl expose deploy httpd --port 80 --type NodePort service/httpd exposed [root@master ~]# kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE httpd NodePort 10.111.22.218 <none> 80:31547/TCP 33s kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14h [root@master ~]# curl 10.111.22.218 test page on v1 [root@master ~]# curl 192.168.235.179:31547 test page on v1
k8s for version updates
[root@master ~]# kubectl set image deploy/httpd httpd=weixiaoya/httpd:v2 deployment.apps/httpd image updated //Create a new pod and delete an old pod until the update is complete [root@master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE httpd-7649d9b878-5lvf7 1/1 Terminating 0 11m httpd-7649d9b878-ck6cq 1/1 Running 0 11m httpd-7649d9b878-pkqkk 1/1 Terminating 0 11m httpd-cb9c79f99-gfk9z 0/1 ContainerCreating 0 10s httpd-cb9c79f99-w722f 1/1 Running 0 11s httpd-cb9c79f99-zcsw5 1/1 Running 0 35s [root@master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE httpd-cb9c79f99-gfk9z 1/1 Running 0 101s httpd-cb9c79f99-w722f 1/1 Running 0 102s httpd-cb9c79f99-zcsw5 1/1 Running 0 2m6s [root@master ~]# kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE httpd NodePort 10.111.22.218 <none> 80:31547/TCP 4m54s //Visit [root@master ~]# curl 10.111.22.218 test page on v2 [root@master ~]# curl 192.168.235.179:31547 test page on v2
RollBACK
[root@master ~]# kubectl rollout undo deploy/httpd deployment.apps/httpd rolled back [root@master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE httpd-7649d9b878-96cnm 1/1 Running 0 8s httpd-7649d9b878-mq6mh 1/1 Running 0 6s httpd-7649d9b878-rtmjt 1/1 Running 0 10s httpd-cb9c79f99-gfk9z 1/1 Terminating 0 3m21s httpd-cb9c79f99-w722f 1/1 Terminating 0 3m22s httpd-cb9c79f99-zcsw5 1/1 Terminating 0 3m46s [root@master ~]# curl 10.111.22.218 test page on v1 [root@master ~]# curl 192.168.235.179:31547 test page on v1