I am tryng to create a pod using kubectl run by creating an yaml file, where first command is creating container but showing state as error and second one is creating with out any issue. what is the difference between these commands?
master $ kubectl run --restart=Never --image=busybox static-busybox --command -- sleep 1000 --dry-run -o yaml //Error container
master $ kubectl run --restart=Never --image=busybox static-busybox --dry-run -o yaml --command -- sleep 1000 //working command
In the first one parameters --dry-run -o yaml are applied to the command you run in the container (sleep), in the second one, they are applied to your kubectl execution
As per the syntax of the kubectl run command needs to be at the end. That's precisely the reason why first command is not working but second one is working.
Usage:
kubectl run NAME --image=image [--env="key=value"] [--port=port] [--dry-run=server|client] [--overrides=inline-json]
[--command] -- [COMMAND] [args...] [options]
Related
I was able to view the app container logs using kubectl -f logs and was able to login to the container using "k exec --stdin --tty -- /bin/bash".
After injecting linkerd, I could not login to the container. However my goal is to check the app logs.
When I use this "k logs -f linkerd-proxy" I could not see the app-related logs.
I tried injecting debug-sidecar as well.
Tried this - "k logs deploy/ linkerd-debug - " and as well as this "k exec -it -c linkerd-debug -- tshark -i any -f "tcp" -V -Y "http.request"
still I couldn't see the exact logs for my app in the pod. Please suggest.
Linkerd works by injecting an additional container into your pods; this is known as the "sidecar" pattern. Your application (or better said container) logs are still accessible, however, as a result of having more than one container in the pod, kubectl requires you to explicitly specify the container name.
For example, assuming you have a pod with two containers (linkerd-proxy and app), you'd have to specify app as the name of the container:
$ kubectl logs -f <pod-name> -c app
# You can specify the container name without the -c flag
$ kubectl logs -f <pod-name> app
# This will work for 'exec' too
$ kubectl exec <pod-name> -c app -it -- sh
It is possible to pass some ENV variables to the pod via the --env option of kubectl run, for example:
kubectl run -ti --rm test --image=busybox --env location=city --env time=morning --namespace default -- sh
I would like to send all the present ENV variables to the pod without specifying all of them the via --env, especially for those that I might not know the variable name. Is there an way to do so? Thanks
You could try something like this:
kubectl run -ti --rm test --image=busybox $(printenv | xargs -I % echo '--env' "%" | tr '\n' ' ') --namespace default -- sh
To exec into a container in a pod, I use the following two commands (note the template flag in the first command trims the output to print just the name of the pods):
$ kubectl get pods --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}'
app-api-6421cdf4fd-x9tbk
app-worker-432f86f54-fknxw
app-frontend-87dd65d49c-6b4mn
app-rabbit-413632c874-s2ptw
$ kubectl exec -it app-api-6421cdf4fd-x9tbk -- bash
It would be nice to exec into the container without having to discover the random guid at the end of the pod name every single time. How can I do this?
You can exec into a pod using the deployment
You can use the following command:
kubectl exec -it deploy/<deployment-name> -- bash
Suppose you have a Deployment with the name myadmin and namespace demo. After deploy, you can exec into the deployment's pod by running the below command:
$ export id=( kubectl get pod -n demo | grep 'myadmin' | awk 'END {print $1}' | xargs echo) && kubectl -n demo exec -it $id -- bash
I believe you expect this.
(sed 's/pod\///' is used below because kubectl get pod -o name gives you names like pod/rabbitmq-0 and you should cut first part)
kubectl exec -it $(kubectl get pod -o name | sed 's/pod\///' | grep api) -- bash
Similar to previous one you can use any known commands to find and sort needed objects. Providing version from your initial question
kubectl exec -it $(kubectl get pod --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}'| grep api) -- bash
I often run tasks like:
Read the log of the service X
or
Attach a shell inside the service Y
I always use something in my history like:
kubectl logs `kubectl get pods --no-headers -o custom-columns=":metadata.name" | grep <partial_name>`
or
kubectl exec -it `kubectl get pods --no-headers -o custom-columns=":metadata.name" | grep <partial_name>` bash
Do you know if kubectl has already something in place for this? Or should I create my own set of aliases?
Kubernetes instances are loosely coupled by the means of labels (key-value pairs). Because of that Kubernetes provides various functionalities that can help you to operate on sets of objects based on labels.
In case you have several pods of the same service good chances that they are managed by some ReplicaSet with the use of some specific label. You should see it if you run:
kubectl get pods --show-labels
Now for aggregating logs for instance you could use label selector like:
kubectl logs -l key=value
For more info please see: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/ .
added to my .zshconfig
sshpod () {
kubectl exec --stdin --tty `kubectl get pods --no-headers -o custom-columns=":metadata.name" | grep ${1} | head -n 1` -- /bin/bash
}
usage
sshpod podname
this
finds all pods
greps needed name
picks the first
sshs into the pod
You can go access a pod by its deployment/service/etc:
kubectl exec -it svc/foo -- bash
kubectl exec -it deployment/bar -- bash
Kubernetes will pick a pod that matches the criteria and send you to it.
You can enable shell autocompletion. Kubectl provides this support for Bash and Zsh which will save you a lot of typing (you will use TAB to get the suggestion/completion).
Kuberentes documentations has a great set of information about how to enable autocompletion under Optional kubectl configurations. It covers Bash on Linux, Bash on MacOS and Zsh.
I have a pod running in kubernetes and i need to run two commands in one line.
Say,
kubectl exec -it <pod name> -n <namespace > -- bash -c redis-cli
above command will open redis-cli
i want to run one more command after exec in one line ie info, i am trying below which is not working:
kubectl exec -it <pod name> -n <namespace > -- bash -c redis-cli -- info
You have to put your command and all the parameters between apostrophes.
in your example it would be:
kubectl exec -it <pod_name> -n <namespace> -- bash -c 'redis-cli info'
From Bash manual: bash -c: If the -c option is present, then commands are read from the first non-option argument commaqnd_string.
Other option (which in my opinion is a better approach) is to get the output from the command with an instant pod, which creates, runs and deletes the pod right after that, like this:
kubectl run --namespace <YOUR_NAMESPACE> <TEMP_RANDOM_POD_NAME> --rm --tty -i --restart='Never' --env REDIS_PASSWORD=$REDIS_PASSWORD --image docker.io/bitnami/redis:5.0.7-debian-10-r0 -- bash -c 'redis-cli -h redis-master -a $REDIS_PASSWORD info'
in my case the password was stored in a envvar called $REDIS_PASSWORD and I'm connecting to a server in a pod called redis-master.
I let it as I runned it to show that you can use as much parameters as needed.
POC:
user#minikube:~$ kubectl run --namespace default redis-1580466120-client --rm --tty -i --restart='Never' --env REDIS_PASSWORD=$REDIS_PASSWORD --image docker.io/bitnami/redis:5.0.7-debian-10-r0 -- bash -c 'redis-cli -h redis-master -a $REDIS_PASSWORD info'
10:41:10.65
10:41:10.66 Welcome to the Bitnami redis container
10:41:10.66 Subscribe to project updates by watching https://github.com/bitnami/bitnami-docker-redis
10:41:10.66 Submit issues and feature requests at https://github.com/bitnami/bitnami-docker-redis/issues
10:41:10.67 Send us your feedback at containers#bitnami.com
10:41:10.67
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
# Server
redis_version:5.0.7
redis_git_sha1:00000000
redis_git_dirty:0
...
{{{suppressed output}}}
...
# CPU
used_cpu_sys:1.622434
used_cpu_user:1.313600
used_cpu_sys_children:0.013942
used_cpu_user_children:0.008014
# Cluster
cluster_enabled:0
# Keyspace
pod "redis-1580466120-client" deleted
Not get your question, do you want to get the information from redis-cli?
kubernetes exec -it <pod name> -n <namespace > -- bash -c 'redis-cli info'
Did you try to link your commands using && ?
kubernetes exec -it <pod name> -n <namespace > -- bash -c redis-cli && info