Earlier this year I gave a talk at a Kubernetes meetup around this topic, might be of interest as well: http://mhausenblas.info/kubectl-in-action/
4 Likes
I’m learning how to make custom resources and custom controllers, and I’ve ended up making a kubectl custom plugin for the k8s.io/sample-controller’s Foo resource:
The nice thing about kubectl custom plugins is that you can write them in any language you want.
6 Likes
I have been happy with complete-alias for Bash. In addition to stuff like k=kubectl, it works well for things like gco='git checkout'.
1 Like
The most important tip I would like to share with all
kubectl [...] --v=8 to display detail req/rsp during your call
5 Likes
Run a shell in a new pod (to examine the kubernetes environment from the inside):
alias kshell='kubectl run -it shell --image giantswarm/tiny-tools --restart Never --rm -- sh'
“--restart Never” ensures that only a pod resource is created (instead of a deployment, replicaset and pod)
“--rm” ensures the pod is deleted when you exit the shell
Of course, if you have existing pods, it may be easier to just run kubectl exec ... sh in one of them (but the container might not have tools like dig, ping, curl, …)
7 Likes
If somebody needs the same as kubectx and kubens for kubecfg see my forked version =>
#dump kubernetes manifests to json
#Ex usage: "kdump -e default -o staging" will export the cluster state to "./staging.json" excluding the "kube-system" and "default" namespaces.
kdumpusage() { echo "Usage: $0 [-e namespace to exclude from backups] [-o name]" 1>&2; }
function kdump () {
while getopts ":e:o:" i; do
case "${i}" in
e)
e=${OPTARG}
;;
o)
o=${OPTARG}
;;
*)
kdumpusage
;;
esac
done
shift $((OPTIND-1))
if [ -z "${e}" ] || [ -z "${o}" ]; then
kdumpusage
fi
for ns in $(kubectl get ns --no-headers | cut -d " " -f1); do
if { [ "$ns" != "kube-system" ]; }; then
kubectl --namespace="${ns}" get --export -o=json svc,rc,rs,deployments,cm,secrets,ds,statefulsets,ing,pv,pvc | \
jq '.items[] |
select(.type!="kubernetes.io/service-account-token") |
del(
.spec.clusterIP,
.metadata.uid,
.metadata.selfLink,
.metadata.resourceVersion,
.metadata.creationTimestamp,
.metadata.generation,
.status,
.spec.template.spec.securityContext,
.spec.template.spec.dnsPolicy,
.spec.template.spec.terminationGracePeriodSeconds,
.spec.template.spec.restartPolicy
)' >> "./$o.json"
fi
done
}
# quickly terminate stuck pods
function kfp () {
for ns in $(kubectl get ns --no-headers | cut -d " " -f1); do
kubectl get pods --namespace="${ns}" | grep 'CrashLoopBackOff\|Error\|Terminating\|ImagePullBackOff\|Pending\|ErrImagePull\|Unknown' | cut -d " " -f 1 | xargs -n 1 kubectl delete pod --namespace="${ns}" --grace-period=0 --force
done
}
2 Likes
A cople of months ago I write a little article ( in Spanish ) to have some tools ready on the terminal, maybe could be interesting for someone:
A small go tool to merge kubernetes contexts to your ~/.kube/config is k8s-ctx-import
For example: cat <kubeconfig> | k8s-ctx-import to import <kubeconfig>'s active context to your kubeconfig in $KUBECONFIG
1 Like
in the jx binary from Jenkins X we added a bunch of handy sub commands for switching namespaces/contexts visually or via CLI arguments
e.g. to switch namespaces just type:
jx ns
and you are prompted with a list of namespaces to choose from. To switch contexts:
the next one is Jenkins X specific - it requires Jenkins X Environment CRDs - but can switch between environments via:
jx env
this then prompts you with your environments (say Dev, Staging, Production without having to worry what the physical namespaces are etc)
jx ctx
the command I love the most though is sometimes you want to switch contexts/namespaces in just 1 shell only (e.g. to tinker on some production cluster). To do that use
jx shell
Then the context updates and the prompt changes to show the new context/namespace - but all other shells stay on the same namespace/context! Then just exit to get back to the global shared context. Super handy
A couple more:
jx rsh
opens a remote shell giving a list of the pods to pick from. You can supply a filter if you prefer (such as a deployment name).
jx log
As above tails the log of the latest pod from a picked list of pods or takes a deployment filter name. Its handy as the log rolls over to the next pod as pods rollover or restart etc
3 Likes
Yes I do and it works, and autocompletion works too.
The only thing is it does not work with the ‘watch’ command (watch k get pods). In this case I use ‘watch kubectl get pods’.
I even have the alias g=gcloud, because I am on GCP
Thanks
1 Like
Fuzzy search kube contexts and easily switch. (Requires fzf)
alias kctx='kubectl config use-context $(kubectl config get-contexts -o=name | fzf)'
https://asciinema.org/a/dltaxEgFpmTzHp4ihhEtZLAKX
1 Like
I made two kubectl plugins. Please try them if you like! 
3 Likes
Hi
I found a little useful tool : shows kubernetes secret with values base64 decoded
e.g :
kubectl get secret my-secret -o yaml | ksd
2 Likes
Update all files stored in ConfigMap at once (Slack #kubernetes-user, thanks @liggitt):
kubectl create configmap your_configmap_here --from-file=/path/to/dir --dry-run -o yaml | kubectl replace -f -
Get all pod names under service / endpoint
kubectl get ep svc_name -n ns -o jsonpath='{range .subsets[*].addresses[*]}{.targetRef.name}{"\n"}{end}'
Get not tainted node(s)
kubectl get nodes -o go-template='{{range .items}}{{if not .spec.taints}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}'
6 Likes
Grab more data from pods
Kubectl get pods -o wide ( will show data such as node which is running on)
Show resources
Kubectl top
The following prepares the ubuntu nodes
#!/bin/bash
apt-get update
apt-get install -y docker.io
cat << EOF > /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
EOF
apt-get update && apt-get install -y apt-transport-https
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF
apt-get update
apt-get install -y kubelet kubeadm kubectl
systemctl is-enabled kubelet && systemctl is-active kubelet
Kubernetes node restart
systemctl is-enabled kubelet && systemctl is-active kubelet
Solution
-
kubeadm reset
-
systemctl restart kubelet
-
kubeadm init --skip-preflight-checks --pod-network-cidr=10.244.0.0/16
I figured out long time ago, this was because the default bash by osx. The solution: upgrade bash
brew install bash
[ -e "$(which bash)" ] && [ "$(grep $(which bash) /etc/shells)" == "" ] && (echo "$(which bash)" | sudo tee -a /etc/shells) && chsh -s "$(which bash)"
1 Like
A very usefull tool to get logs from different pods in one stream. This tool helped me a lot. Hope will help someone else 
3 Likes