As our main tool for operating K8S, kubectl has a wealth of functions, but it is still inconvenient to use if it is not polished. Today, let's see how to polish our kubectl to make it easier to use.
1, Command auto completion
kubectl provides many commands. If it is too tired to manually type one character at a time, how to configure automatic completion? Take ubuntu system as an example:
1. Install the auto completion tool
$ sudo apt update Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease Hit:2 http://security.ubuntu.com/ubuntu bionic-security InRelease Hit:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease Hit:4 https://download.docker.com/linux/ubuntu bionic InRelease Hit:5 http://archive.ubuntu.com/ubuntu bionic-backports InRelease Reading package lists... Done Building dependency tree Reading state information... Done 144 packages can be upgraded. Run 'apt list --upgradable' to see them. $ sudo apt install bash-completion Reading package lists... Done Building dependency tree Reading state information... Done bash-completion is already the newest version (1:2.8-1ubuntu1). 0 upgraded, 0 newly installed, 0 to remove and 144 not upgraded.
PS: for centos system, use yum install bash completion - y command to install
2. Configure automatic completion
Bash:
source <(kubectl completion bash) echo "source <(kubectl completion bash)" >> ~/.bashrc
Zsh:
source <(kubectl completion zsh) echo "[[ $commands[kubectl] ]] && source <(kubectl completion zsh)" >> ~/.zshrc
After configuration, you can use the Tab key to automatically complete the command!
2, Configure kubectl alias
We can simplify kubectl command and edit by setting alias bashrc file, add the following:
alias sudo='sudo ' alias k='kubectl' alias ka='kubectl apply --recursive -f' alias kex='kubectl exec -i -t' alias klo='kubectl logs -f' alias kg='kubectl get' alias kd='kubectl describe'
PS: alias sudo is to solve the problem of unavailable aliases under sudo
Remember to execute source ~ /. After saving Bashrc ha, then let's experience:
$ sudo ka webapp_pod.yaml
pod/webapp created
$ sudo kg pods
NAME READY STATUS RESTARTS AGE
webapp 0/2 ContainerCreating 0 7s
$ sudo kd pod webapp
Name: webapp
Namespace: default
Priority: 0
Node: ayato/172.16.194.135
Start Time: Wed, 09 Feb 2022 14:04:44 +0000
Labels: app=webapp
Annotations: <none>
Status: Running
IP: 172.17.0.6
IPs:
IP: 172.17.0.6
Containers:
webapp:
Container ID: docker://d9ddf9dd47de12b53f2119bf75df6706bee2e7711509638ad52adc9addeda704
Image: 172.16.194.135:5000/webapp:1.0
Image ID: docker-pullable://172.16.194.135:5000/webapp@sha256:df3a447a013ada0642dec67bb31976f42f1a0699a68873d0452f514fa24e5c77
Port: 5000/TCP
Host Port: 0/TCP
State: Running
Started: Wed, 09 Feb 2022 14:04:46 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/tmp from webapp-logs (rw)
/var/run/secrets/kubernetes.io/serviceaccount from default-token-pcr2h (ro)
busybox:
Container ID: docker://6a6a35a628a782fc643af3dd49986bbc77c23de1ae4726bc521c77f61abbbf5d
Image: busybox
Image ID: docker-pullable://busybox@sha256:afcc7f1ac1b49db317a7196c902e61c6c3c4607d63599ee1a82d702d249a0ccb
Port: <none>
Host Port: <none>
Command:
sh
-c
tail -f /logs/log.out
State: Running
Started: Wed, 09 Feb 2022 14:06:53 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/logs from webapp-logs (rw)
/var/run/secrets/kubernetes.io/serviceaccount from default-token-pcr2h (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
webapp-logs:
Type: EmptyDir (a temporary directory that shares a pod's lifetime)
Medium:
SizeLimit: <unset>
default-token-pcr2h:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-pcr2h
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 2m23s default-scheduler Successfully assigned default/webapp to ayato
Normal Pulled 2m22s kubelet Container image "172.16.194.135:5000/webapp:1.0" already present on machine
Normal Created 2m21s kubelet Created container webapp
Normal Started 2m21s kubelet Started container webapp
Normal Pulling 2m21s kubelet Pulling image "busybox"
Normal Pulled 15s kubelet Successfully pulled image "busybox" in 14.633078305s
Normal Created 15s kubelet Created container busybox
Normal Started 14s kubelet Started container busyboxIt really feels like flying!!!
3, Context and Namespace switching
When we use kubectl on the company's container platform, we often need to switch between context and namespace, resulting in cumbersome commands. Is there a simple way—— kubectx
kubectx installation
$ sudo git clone https://github.com/ahmetb/kubectx /opt/kubectx Cloning into '/opt/kubectx'... remote: Enumerating objects: 1457, done. remote: Counting objects: 100% (172/172), done. remote: Compressing objects: 100% (115/115), done. remote: Total 1457 (delta 85), reused 97 (delta 51), pack-reused 1285 Receiving objects: 100% (1457/1457), 905.30 KiB | 69.00 KiB/s, done. Resolving deltas: 100% (817/817), done. $ sudo ln -s /opt/kubectx/kubens /usr/local/bin/kubectl-ns $ sudo ln -s /opt/kubectx/kubectx /usr/local/bin/kubectl-ctx
Let's look at the effect:
$ sudo k ctx minikube $ sudo k ctx minikube Switched to context "minikube". $ sudo k ns default kube-node-lease kube-public kube-system kubernetes-dashboard $ sudo k ns kube-public Context "minikube" modified. Active namespace is "kube-public". $ sudo k ns default Context "minikube" modified. Active namespace is "default".
4, Track and view logs of multiple pods
We usually use kubectl logs command to view Pod logs, but it cannot track and view multiple Pod logs at the same time through the - f parameter, which is inconvenient. After all, each service in the actual production environment will have multiple pods. At this time, we can use stern, which has the following capabilities:
- Allows you to use regular expressions to select the PodName you want to view
- Show different colors for logs of different pods
- During the tracking log process, if a new Pod that meets the rules is created, it will be automatically added to the output
First install Stern (it may be slow to download stern. You can try it several times):
wget https://github.com/wercker/stern/releases/download/1.11.0/stern_linux_amd64 sudo mv stern_linux_amd64 /usr/local/bin/kubectl-tail sudo chomd +x /usr/local/bin/kubectl-tail
After installation, let me feel the charm of stern. There are two containers in my Pod: webapp and busybox. If you use kubectl logs, you have to specify a specific container, but there is no such restriction when using stern.
$ sudo k tail . + webapp › busybox + webapp › webapp webapp busybox 14:04:53.197 [INFO ] [main] [org.apache.coyote.http11.Http11NioProtocol] Initializing ProtocolHandler ["http-nio-4567"] webapp busybox 14:04:53.200 [INFO ] [main] [org.apache.catalina.core.StandardService] Starting service [Tomcat] webapp busybox 14:04:53.201 [INFO ] [main] [org.apache.catalina.core.StandardEngine] Starting Servlet engine: [Apache Tomcat/9.0.41] webapp busybox 14:04:53.324 [INFO ] [main] [org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/]] Initializing Spring embedded WebApplicationContext webapp busybox 14:04:53.325 [INFO ] [main] [org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext] Root WebApplicationContext: initialization completed in 2952 ms webapp busybox 14:04:53.801 [INFO ] [main] [org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor] Initializing ExecutorService 'applicationTaskExecutor' webapp busybox 14:04:54.264 [WARN ] [main] [org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$DefaultTemplateResolverConfiguration] Cannot find template location: classpath:/templates/ (please add some templates or check your Thymeleaf configuration) webapp busybox 14:04:54.377 [INFO ] [main] [org.apache.coyote.http11.Http11NioProtocol] Starting ProtocolHandler ["http-nio-4567"] webapp busybox 14:04:54.481 [INFO ] [main] [org.springframework.boot.web.embedded.tomcat.TomcatWebServer] Tomcat started on port(s): 4567 (http) with context path '' webapp busybox 14:04:54.509 [INFO ] [main] [org.demo.webapp.todolist.TodoListApplication] Started TodoListApplication in 6.235 seconds (JVM running for 8.074) webapp webapp webapp webapp . ____ _ __ _ _ webapp webapp /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ webapp webapp ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ webapp webapp \\/ ___)| |_)| | | | | || (_| | ) ) ) ) webapp webapp ' |____| .__|_| |_|_| |_\__, | / / / / webapp webapp =========|_|==============|___/=/_/_/_/ webapp webapp :: Spring Boot :: (v2.4.2) webapp webapp webapp webapp 14:04:50.124 [INFO ] [main] [org.demo.webapp.todolist.TodoListApplication] Starting TodoListApplication v1.0-SNAPSHOT using Java 1.8.0_111 on webapp with PID 1 (/opt/soft/webapp.jar started by root in /opt/soft) webapp webapp 14:04:50.165 [INFO ] [main] [org.demo.webapp.todolist.TodoListApplication] No active profile set, falling back to default profiles: default webapp webapp 14:04:53.158 [INFO ] [main] [org.springframework.boot.web.embedded.tomcat.TomcatWebServer] Tomcat initialized with port(s): 4567 (http) webapp webapp 14:04:53.197 [INFO ] [main] [org.apache.coyote.http11.Http11NioProtocol] Initializing ProtocolHandler ["http-nio-4567"] webapp webapp 14:04:53.200 [INFO ] [main] [org.apache.catalina.core.StandardService] Starting service [Tomcat] webapp webapp 14:04:53.201 [INFO ] [main] [org.apache.catalina.core.StandardEngine] Starting Servlet engine: [Apache Tomcat/9.0.41] webapp webapp 14:04:53.324 [INFO ] [main] [org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/]] Initializing Spring embedded WebApplicationContext webapp webapp 14:04:53.325 [INFO ] [main] [org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext] Root WebApplicationContext: initialization completed in 2952 ms webapp webapp 14:04:53.801 [INFO ] [main] [org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor] Initializing ExecutorService 'applicationTaskExecutor' webapp webapp 14:04:54.264 [WARN ] [main] [org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$DefaultTemplateResolverConfiguration] Cannot find template location: classpath:/templates/ (please add some templates or check your Thymeleaf configuration) webapp webapp 14:04:54.377 [INFO ] [main] [org.apache.coyote.http11.Http11NioProtocol] Starting ProtocolHandler ["http-nio-4567"] webapp webapp 14:04:54.481 [INFO ] [main] [org.springframework.boot.web.embedded.tomcat.TomcatWebServer] Tomcat started on port(s): 4567 (http) with context path '' webapp webapp 14:04:54.509 [INFO ] [main] [org.demo.webapp.todolist.TodoListApplication] Started TodoListApplication in 6.235 seconds (JVM running for 8.074)