[ Kube 12 ] Init Containers in Kubernetes Cluster

In this video, I will show you how to use Init containers in Kubernetes cluster.
Github: github.com/justmeandopensourc...
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[@mathewkargarzadeh3158]

Excellent illustration of the init container under the hood. I loved it. in our environment for pod deployment we uses the init container side-car to get the deployment configuration from the vault. this is a subject that not too many Engineers delve into. and kubectl describe pod should tell you if the init container has any issue before starting the real application container. Thank you for the inside you shared in your illustration. you are the Man!! Thanks again. Mat.

[@justmeandopensource]

Hi Matthew, thanks for watching this video and taking time to comment/appreciate. Cheers.

[@DeepakKumar-fc3hn]

very nicely explained thanks for such videos

[@justmeandopensource]

Hi Deepak, thanks for watching. Cheers.

[@rahmatjulizar6397]

Thanks so much for this tutorial.

[@justmeandopensource]

Hi Rahmat, Thanks for watching. Cheers.

[@mrjamiebowman1337]

this was a really good video. Thanks!

[@justmeandopensource]

Hi Jamie, thanks for watching.

[@niyashaneef8840]

Well Explained .Thnk You

[@justmeandopensource]

Hi Niyas, thanks for watching.

[@snehotoshbanerjee1938]

Great video!

[@justmeandopensource]

Thanks for watching.

[@vamshidharreddygottam2626]

It's good effort of you for making such nice videos, but small suggestion from my side, plz try to avoid the sound "cho cho" (observe at 11th sec) which is repeating throughout all the videos.

[@justmeandopensource]

Hi Vamshidhar, thanks for watching this video and taking time to give feedback. Thats a great observation. I just noticed it after you mentioned it. I don't think that I am making that sound. Anyways, will try to avoid that if possible in future videos. Thanks, Venkat

[@indranilbanerjee5521]

Gr8 explanation

[@justmeandopensource]

Hi Indranil, thanks for watching. Cheers.

[@ptkalex2627]

Good one VN

[@justmeandopensource]

Hi Alex, thanks for watching this video.

[@TheAirak]

Many thanks!

[@justmeandopensource]

You are welcome.

[@derekreed6798]

Nice vid.

[@justmeandopensource]

Thanks for watching Derek.

[@vujanic88]

great, thanks

[@justmeandopensource]

You are welcome. Thanks for watching.

[@jagadeesh0014]

Hi Venkat,Once again many more thanks, This video helps a lot to understand the concepts, what is the main difference between jobs and INIT containers.

[@justmeandopensource]

Hi Jagan, thanks for watching.

[@justmeandopensource]

kubernetes.io/docs/concepts/workloads/pods/init-containers/ kubernetes.io/docs/concepts/workloads/controllers/job/

[@saivenkataratnamemmani1936]

can you please explain what is CNI in layman's terms or real time usage. Thank you

[@anilmahaptara]

Hi Venkat, Your videos are much informative and has been a great help for me. I have been learning from your videos. I just have one question, can we see the logs of the init container?

[@justmeandopensource]

Hi Anil, thanks for watching. Yes, you can see the logs of any container in a pod. Since in this situation you have more than one container running in the same pod, you need to specify the container name as well when looking at the logs. $ kubectl logs -c cheers.

[@nikitashesterikov1175]

Its awesome, fast and wide. Also a question: what is the autocomplit tool? Its awesome too!

[@justmeandopensource]

Hi Nikita, thanks for watching. I use Manjaro Linux distribution with Gnome desktop environment. I also use ZSH shell with oh-my-zsh. For the auto complete feature, I used zsh-autosuggestions plugin with zsh. It suggests commands based on your command history. I have explained that in the below video. kzbin.info/www/bejne/qaCkqIinZ8iEfrM Cheers.

[@biahoi87]

A very informative video, thanks and keep it up. Although I don't get it when you got only one pod running in one worker node #12:44 but you can access nginx index page from both node at browser

[@justmeandopensource]

Hi Quan, thanks for watching this video.

[@justmeandopensource]

Sorry I missed to answer your question. Yes there is only one nginx pod running on one worker node. But you will be able to access the exposed service on any worker nodes as the service is exposed with type "NodePort". If you want to know more about NodePort service type, please check the below link (under the section titled: "Publishing services - service types") kubernetes.io/docs/concepts/services-networking/service/ Thanks, Venkat

[@sarankumaark]

@@justmeandopensource I am also using the same nodePort but I am able to access the application using only one worker node.. As per my understanding, the container is running in the single node..then how we are getting response from both nodes. Thanks, Saran

[@justmeandopensource]

@@sarankumaark The fundamental concept is that you can reach any worker node on nodeport and will be able to reach the service even if the pods are not running on that worker node. Its all possible because of the overlay network. Worker nodes will be able to forward traffic to other nodes where the pods are actually running. If you can access only from the worker node where the pods are running and not from other worker nodes nodeport, then you have some networking problem in your cluster.

[@sarankumaark]

@@justmeandopensource Thanks for sharing details i will check...keep doing the good thing..wishes from Tamil Nadu🔥🎉

[@venugopalkrishna4463]

super

[@justmeandopensource]

Thanks for watching this video.

[@avijitdhar2807]

Hi, I am getting "error: unable to recognize "3-init-container.yaml": no matches for kind "Deployment" in version "extensions/v1beta1"" by cluster version is kubectl version --short Client Version: v1.16.0 Server Version: v1.16.1 Could you please tell me what will be the apiVersion I can use. Thanks in advance.

[@justmeandopensource]

Hi Avijit, I did a video about this. kzbin.info/www/bejne/a2OoomNjedinqac ApiVersion should be apps/v1 Thanks

[@vijayakoli5782]

Hi, can used this init container to lunch jenkins server, so that it can help us to setup CI/CD pipeline

[@justmeandopensource]

Hi Vijaya, thanks for watching. I am not sure what you are asking here. Init containers are something that you run to prepare something for your main container. For example, if your main pod needs some data to work, you can have init container fetch that data and keep it ready so that main container when launched will have data ready. The main container will start only when the init container finishes it work successfully. Hope this makes sense. Cheers.

[@Bayaprakashreddyc]

your the best in teaching man, seriously, I have a small doubt, In init YAML file, under init container path for saving HTML is different and under container nginx mount path is different, how do index.html file will copy to the /usr/share/nginx/html , since it's path is /nginx-data

[@justmeandopensource]

Hi, thanks for watching. It doesn't matter where you mount the volume. But I have used the same volume in both init and nginx containers. I defined a volume in the volume section of the pod. I mounted that volume in init container. Updated the content then mounted the same volume in nginx container under nginx web root.

[@Bayaprakashreddyc]

Thank you

[@justmeandopensource]

@@Bayaprakashreddyc you are welcome.

[@vujanic88]

does init container must have image specified or we can specify just command that we want to execute?

[@justmeandopensource]

Hi thanks for watching. You can't run a container without specifying the image.. Container is basically an image.

[@richardwang3438]

nice video Venkat, thank you for sharing. Is init container same as pause container or infra container? I know pause container is the first container that gets running in a pod to serve as the basis of the namespace and PID 1.

[@justmeandopensource]

HI Richard, thanks for watching this video. I never heard of pause container or infra container. Init containers are not parent containers but the first container to start in a pod. It is used for any preparatory work for your main container. For example, if your main container needs to checkout a file or something for its operation, you can have the init container do that job and when the main container starts, it will have the file ready. You can have more than one init containers. Bear in mind that only when all the init containers execute successfully, the control will then be passed to the main container. If init containers fails for some reason, then main container won't be invoked/started. Cheers.

[@richardwang3438]

@@justmeandopensource hi, when you run 'docker ps' on any worker node, you can see containers like 'k8s.gcr.io/pause', they are pause containers

[@justmeandopensource]

@@richardwang3438 Thanks for introducing me to a new concept. I am going to read about it. Cheers.

[@richardwang3438]

@@justmeandopensource cheers!

[@justmeandopensource]

@@richardwang3438 :)

[@shanmugamn789]

Hi nice video, if possible to mount two volumes emtdir in init container section ? We need to mount same volume in two different file path to the main container. I had tried but it's fails. Pls help ....

[@justmeandopensource]

Hi, thanks for watching. Yes, you can mount more than one volumes (of any types) in your pod.

[@shanmugamn789]

@@justmeandopensource I tried create mount but it's fails, my requirement is copy two different file from two image. So I used init container but it fails . It possible call two emptdir volume in init container section ?

[@justmeandopensource]

Yeah. Thats possible.

[@shanmugamn789]

@@justmeandopensourcelet me share my code , if possible to share any samples to call two volumes .

[@shanmugamn789]

We can use job in place of init container ?

[@jahanpanahy]

Hi, First of all thanks for the video. We have some different scenario. We would like to prepare our node before depployment happends. For example we want to install Nvidia drivers because we have application which uses gpu to be deployed on this node of cluster. Is it possible to run script which will install Nvidia drivers before application deployment? Any guidance would be pretty helpful. Thanks again for the video. Keep up the good work.

[@justmeandopensource]

Hi Hiren, thanks for watching. Where do you want to install nvidia drivers? In the application pod or on the underlying Kubernetes node? If its on the pod, you can either bake it in the container image if its not huge in size or you can use init container to do exactly this. Cheers.

[@jahanpanahy]

@@justmeandopensource No, we want to have nvidia drivers installed on the underlying node as it will be having GPU required to run deep learning application. Any ideas there?

[@user-ye8zh3ep7m]

@@jahanpanahy k8s is not a golden hammer, use ansible, aws cloud formation, chef to provision your infra

[@kunafeh]

It's OK to speak in your native accent. Everyone is able to make out the difference between a fake and real accent.

[@justmeandopensource]

Thanks for your comment. I am not trying to impress anyone. My motive is to learn stuff and help the community. For your information, that's my natural accent. If I had focused on the accent, I wouldn't be able to deliver the proper content. That's not my aim. If you cared about the content of the video, you wouldn't have made this comment. Feeling really sorry for you that you had to write this comment.

[@romantsyupryk3009]

Thanks so much for this tutorial.

[@justmeandopensource]

Hi Roman, thanks for watching.