I am writing a shell script for executing a pod for which the syntax is:
winpty kubectl --kubeconfig="C:\kubeconfig" -n namespace exec -it podname bash
This works fine but since podname is not stable and changes for every deployment so is there any alternative for this?
Thanks.
You can use normally $ kubectl exec command but define value for changing pod name.
Assuming that you have deployment and labeled pods: app=example, simply execute:
$ kubectl exec -it $(kubectl get pods -l app=example -o custom-columns=:metadata.name) -- bash
EDIT:
You can also execute:
POD_NAME = $(kubectl get pods -l app=example -o custom-columns=":metadata.name")
or
POD_NAME = $(kubectl get pods -l app=example -o jsonpath = "{. Items [0] .metadata.name}")
finally
$ winpty kubectl exec -ti $POD_NAME --bash
Make sure that you execute command in proper namespace - you can also add -n flag and define it.
You can use the following command:
kubectl -n <namespace> exec -it deploy/<deployment-name> -- bash
Add a service to your application:
As you know, pods are ephemeral; They come in and out of existence dynamically to ensure your application stays in compliance with your configuration. This behavior implements the scaling and self-healing aspects of kubernetes.
You application will consist of one or more pods that are accessible through a service , The application's service name and address does not change and so acts as the stable interface to reach your application.
This method works both if your application has one pod or many pods.
Does that help?
Running below command to execute my tests on docker container
sudo docker exec -i 6d49272f772c bash -c "mvn clean install test"
Above command running on Jenkins execute bash. But Jenkins console does not show the logs for test execution.
I had a similar problem with docker start (which is similar to docker exec). I used the -i option and it would work fine outside Jenkins, but the console in Jenkins didn't show any output from this command. I replaced -i with -a similar to the following:
sudo docker container create -it --name container-name some-docker-image some-command
sudo docker container start -a container-name
sudo docker container rm -f container-name
The docker exec method doesn't have a -a option so possibly removing the -i option would work too (since you are not interacting with the container in Jenkins), so if that doesn't work than you can convert to the following commands and achieve similar results with standard out being captured.
I have a bash script that is supposed to execute other bash scripts using "docker exec" which are installed in different docker containers. Although each command works correctly when started manually, the script stops after the execution of first docker exec command.
Example:
#!/bin/bash
...
docker exec -it mysql_container /scripts/import_database.sh ## Scripts stops here...
docker exec -it web_container /scripts/copy_doc_root.sh
...
What am I missing? ;)
Thanks for your help!
David
Use docker exec -d since you neither want a terminal nor an interactive session.
I am trying to create a shell script for setting up a docker container. My script file looks like:
#!bin/bash
docker run -t -i -p 5902:5902 --name "mycontainer" --privileged myImage:new /bin/bash
Running this script file will run the container in a newly invoked bash.
Now I need to run a script file (test.sh)which is already inside container from the above given shell script.(eg: cd /path/to/test.sh && ./test.sh)
How to do that?
You can run a command in a running container using docker exec [OPTIONS] CONTAINER COMMAND [ARG...]:
docker exec mycontainer /path/to/test.sh
And to run from a bash session:
docker exec -it mycontainer /bin/bash
From there you can run your script.
Assuming that your docker container is up and running, you can run commands as:
docker exec mycontainer /bin/sh -c "cmd1;cmd2;...;cmdn"
I was searching an answer for this same question and found ENTRYPOINT in Dockerfile solution for me.
Dockerfile
...
ENTRYPOINT /my-script.sh ; /my-script2.sh ; /bin/bash
Now the scripts are executed when I start the container and I get the bash prompt after the scripts has been executed.
In case you don't want (or have) a running container, you can call your script directly with the run command.
Remove the iterative tty -i -t arguments and use this:
$ docker run ubuntu:bionic /bin/bash /path/to/script.sh
This will (didn't test) also work for other scripts:
$ docker run ubuntu:bionic /usr/bin/python /path/to/script.py
This command worked for me
cat local_file.sh | docker exec -i container_name bash
You could also mount a local directory into your docker image and source the script in your .bashrc. Don't forget the script has to consist of functions unless you want it to execute on every new shell. (This is outdated see the update notice.)
I'm using this solution to be able to update the script outside of the docker instance. This way I don't have to rerun the image if changes occur, I just open a new shell. (Got rid of reopening a shell - see the update notice)
Here is how you bind your current directory:
docker run -it -v $PWD:/scripts $my_docker_build /bin/bash
Now your current directory is bound to /scripts of your docker instance.
(Outdated)
To save your .bashrc changes commit your working image with this command:
docker commit $container_id $my_docker_build
Update
To solve the issue to open up a new shell for every change I now do the following:
In the dockerfile itself I add RUN echo "/scripts/bashrc" > /root/.bashrc". Inside zshrc I export the scripts directory to the path. The scripts directory now contains multiple files instead of one. Now I can directly call all scripts without having open a sub shell on every change.
BTW you can define the history file outside of your container too. This way it's not necessary to commit on a bash change anymore.
Thomio's answer is helpful but it expects the script to exist inside the image. If you have a one-of script that you want to run/test inside a container (from command-line or to be useful in a script), then you can use
$ docker run ubuntu:bionic /bin/bash -c '
echo "Hello there"
echo "this could be a long script"
'
Have a look at entry points too. You will be able to use multiple CMD
https://docs.docker.com/engine/reference/builder/#/entrypoint
If you want to run the same command on multiple instances you can do this :
for i in c1 dm1 dm2 ds1 ds2 gtm_m gtm_sl; do docker exec -it $i /bin/bash -c "service sshd start"; done
This is old, and I don't have enough reputation points to comment. Still, I guess it is worth sharing how one can generalize Marvin's idea to allow parameters.
docker exec -i mycontainer bash -s arg1 arg2 arg3 < mylocal.sh
I'm having k8s cluster with 3 minions, master and haproxy in front. When I use
kubectl exec -p $POD -i -t -- bash -il
for accessing bash in the pod (it is a single container in this case) I get in and after something like 5 mins I get dropped out of the terminal. If I reenter the container I can see my old bash process running, with a new started for my new connection. Is there a way to prevent this from happening? When I'm using docker exec it works fine and doesn't drop me so I guess it is from kubernetes.
As a bonus question - is there a way to increase the characters per line when using kubectl exec? I get truncated output that is different from docker exec.
Thanks in advance!
It is a known issue -
https://github.com/kubernetes/kubernetes/issues/9180
The kubelet webserver times out.
i have resolve by add env COLUMNS=$COLUMNS LINES=$LINES before bash kubectl exec -ti busybox env COLUMNS=$COLUMNS LINES=$LINES bash