I am very new to Openshift Origin. I am now trying out the possibility of deploying my docker containers in OpenShift origin.
For that I created a very simple docker container that adds two numbers and produce the result:
https://github.com/abrahamjaison01/openshifttest
I created a docker image locally and a public docker image in docker hub:
docker pull abrahamjaison/openshifttest
I run the docker image locally as follows:
[root#mymachine /]# docker run -it --rm abrahamjaison/openshifttest
Enter first large number
12345
Enter second large number
54321
Result of addition = 66666
Since I am completely new to Openshift, I have no idea on how to deploy this in the Openshift environment.
I created a new project: oc new-project openshifttest
Then a new app: oc new-app docker.io/abrahamjaison/openshifttest
But then I do not know how I can access the console/terminal to provide the inputs. Also many a times when I run this I get the output as "deployment failed" when I issue the command "oc status".
Basically I would like to know how I can deploy this docker image on openshift and how I will be able to access the terminal to provide the inputs for performing the addition.
Could someone help me out with this?
OpenShift is principally for long running services such as web application and database. It isn't really intended for running a Docker container to wrap a command which then returns a result to the console and exits.
To get a better understand of how OpenShift 3 is used, download and read the free eBook at:
https://www.openshift.com/promotions/for-developers.html
The closest you will get to do the same as docker run is the oc run command, but it sort of defeats the whole point of what OpenShift is for. You are better off using Docker on your own system for what you are describing.
A guess at the command you would use if really wanted to try would be:
oc run test -i --tty --rm --image=abrahamjaison/openshifttest
As I say though, not really intended for doing this. That oc run exists is more for testing when having deployment problems for your applications.
Following the "Creating an Application From an Image" part, the syntax should be:
oc new-app abrahamjaison/openshifttest
By default, OpenShift will look for the image in DockerHub.
But that supposes you have pushed your GitHub image there first: see "Store images on Docker Hub". That might be the missing step in your process.
The interaction with oc is done with the OpenShift CLI or web console, as illustrated in the authentication page.
Related
What I want to achieve is that I give a colleague a docker container to run locally (via docker run) on his PC. I build this often via Gitlab CI and push it with a version tag (Semver 2.0) to Nexus.
Colleague should get a simple bash script like so:
#!/bin/bash
docker run -it -p 8080:80 nexus.company.net/goodservice:latest --dependency-overrides=local
echo "find the good service under http://localhost:8080, have fun!"
("--dependency-overrides" is a simple method I just implemented so that he can run the whole thing without Redis, I replace the implementations in the DI container this way.)
Problem:
Once a version (say: 1.0.1-pre.5) is downloaded, "latest" doesn't do any updates anymore.
I could EASILY fix it by using "--pull=always" on docker run but it's a .NET image of overall size about 100 MB (it's alpine already, but it still is a lot). Colleague is on a metered 4G Internet connection.
Is there any method to make docker check if "latest" is something else now? Didn't find anything in the documentation.
(If somebody from docker (or CNCF?) reads this: would be great to have an option like "--pull=updated". :-))
Any ideas?
Add a docker pull command to your script. It'll only pull the image if it has been updated.
#!/bin/bash
docker pull nexus.company.net/goodservice:latest
docker run -it -p 8080:80 nexus.company.net/goodservice:latest --dependency-overrides=local
echo "find the good service under http://localhost:8080, have fun!"
If you want to limit the amount of data needed to be downloaded, you want to make sure that you typically only touch the last layer of the image when you create a new version. That way your colleague only needs to download the last layer and not the entire image.
I'm new to docker.Most of the tutorials on docker cover the same thing.I'm afraid I'm just ending up with piles of questions,and no answers really. I've come here after my fair share of Googling, kindly help me out with these basic questions.
When we install a docker,where it gets installed? Is it in our computer in local or does it happen in cloud?
Where does containers get pulled into?I there a way I can see what is inside the container?(I'm using Ubuntu 18.04)
When we pull an image.Docker image or clone a repository from
Git.where does this data get is stored?
Looks like you are confused after reading to many documents. Let me try to put this in simple words. Hope this will help.
When we install a docker,where it gets installed? Is it in our
computer in local or does it happen in cloud?
We install the docker on VM be it you on-prem VM or cloud. You can install the docker on your laptop as well.
Where does containers get pulled into?I there a way I can see what is
inside the container?(I'm using Ubuntu 18.04)
This question can be treated as lack of terminology awareness. We don't pull the container. We pull the image and run the container using that.
Quick terminology summary
Container-> Containers allow you to easily package an application's code, configurations, and dependencies into a template called an image.
Dockerfile-> Here you mention your commands or infrastructure blueprint.
Image -> Image gets derived from Dockerfile. You use image to create and run the container.
Yes, you can log inside the container. Use below command
docker exec -it <container-id> /bin/bash
When we pull an image.Docker image or clone a repository from
Git.where does this data get is stored?
You can pull the opensource image from Docker-hub
When you clone the git project which is docerized, you can look for Dockerfile in that project and create the your own image by build it.
docker build -t <youimagenae:tag> .
When you build or pull the image it get store in to your local.
user docker images command
Refer the below cheat-sheet for more commands to play with docker.
The docker daemon gets installed on your local machine and everything you do with the docker cli gets executed on your local machine and containers.
(not sure about the 1st part of your question). You can easily access your docker containers by docker exec -it <container name> /bin/bash for that you will need to have the container running. Check running containers with docker ps
(again I do not entirely understand your question) The images that you pull get stored on your local machine as well. You can see all the images present on your machine with docker images
Let me know if it was helpful and if you need any futher information.
I am currently working on the following scenario
I am trying to setup a container in OpenShift that runs a Jenkins that is itsself able to run docker to make use of declarative pipelines where the build is running in it's own docker container. This basically makes it necessary to install and run docker inside this container.
I have been working on it on quite some time now. Checked dozens of posts and threads online but I have not been able to accomplish it. Basically I got so far
I can install docker in my container (from the baseimage openshift/jenkins-2-centos7:latest)
I can't get docker to run as this makes use of systemctl which
Now I read that systemctl is not working inside docker containers or at least highly unrecommended as it interferes with the PID 1 in the system. Without
systemctl start docker
that will leave me with docker beeing unable to connect with the daemon (as expected) and the error message
Can't connect to docker daemon. Is 'docker -d' running on this host?
So I tried to set up the daemon myself using
the follwoing in my Dockerfile
RUN usermod -aG docker $(whoami)
RUN dockerd -H unix:///var/run/docker.sock
which will also not work telling me that cgroups cannot be mounted. After some more research I found that this could be handled with the cgroupfs-mount script from
https://github.com/tianon/cgroupfs-mount/tree/master
But also here I got no luck leaving me with the following error
Error starting daemon: Error initializing network controller: error obtaining controller instance: failed to create NAT chain DOCKER: iptables failed: iptables -t nat -N DOCKER: iptables v1.4.21: can't initialize iptables table `nat': Permission denied (you must be root)
Perhaps iptables or your kernel needs to be upgraded.
Now after hours I am out of ideas. Does anyone have an idea how to make docker work inside of OpenShift? Would be really greatful
I am trying to setup a container in OpenShift that runs a Jenkins that is itsself able to run docker to make use of declarative pipelines where the build is running in it's own docker container. This basically makes it necessary to install and run docker inside this container.
I don't think your conclusion here is the only possibility, and what I'll describe below is an easier approach to get what (I think) you want! :) If there are any other use cases that you have than these 3 I'll describe, let me know and I'll try to update to cover them:
Pipelines running in their own containers
Running additional containers from Pipelines
Building container images from Pipelines
Pipelines running in their own containers
For this case, there's the excellent Kubernetes plugin.
With this plugin, you add a Kubernetes/OpenShift cloud to the Jenkins global config. This can either be the one in which Jenkins is running (if you use the Jenkins image provided by OpenShift, this gets added by default at least), or an external cluster.
Inside that configuration, you can define PodTemplates (again, there are a couple of examples provided in the Jenkins image provided by OpenShift), or you can specify that in your pipeline directly also I think. When your pipeline requests a node/agent with a label that matches one of these (and there are no long-running agents that match), then a pod will be created from that template, and your pipeline execution will happen inside a container in that. Once it's no longer needed, it will be deprovisioned again.
Here are the pipeline steps exposed by this plugin: https://jenkins.io/doc/pipeline/steps/kubernetes/
Running additional containers from Pipelines
As part of your pipeline, you may want to run some tests, and those may expect to be able to interact with e.g. a database. You can create resources for that in your OpenShift project (e.g. a Deployment & expose it with a Service), and tear them down after. The openshift-client plugin is very useful here and has docs on how to interact with OpenShift.
Building container images from Pipelines
If your goal is to build container images from pipelines, remember that OpenShift also exposes this capability (depending on the security configuration) through Builds. Just like in the previous section, you can use the openshift-client plugin to create and trigger builds.
For more information on the Jenkins image that's maintained by OpenShift (and generally how to do useful things in Jenkins on OpenShift), there's this dedicated page in the OpenShift docs.
You have this article by #jpetazzo, from Docker team, about Docker In Docker (DinD):
article:
The primary purpose of Docker-in-Docker was to help with the development of Docker itself. Many people use it to run CI (e.g. with Jenkins), which seems fine at first, but they run into many “interesting” problems that can be avoided by bind-mounting the Docker socket into your Jenkins container instead.
DinD Repo:
This work is now obsolete, thanks to the combined efforts of some amazing people like #jfrazelle and #tianon, who also are black belts in the art of putting IKEA furniture together.
If you want to run Docker-in-Docker today, all you need to do is:
docker run --privileged -d docker:dind
So here is an article using another approach to build docker containers with Jenkins inside a docker container:
docker run -p 8080:8080 \
-v /var/run/docker.sock:/var/run/docker.sock \
--name jenkins \
jenkins/jenkins:lts
So you may want to adapt one of this solutions to your OpenShift scenario. I hope it solves your issue.
You'll need a privileged pod running jenkins wich mounts the openshift node docker socket. This is a bad idea as jenkins'll launch container outside kubernetes semantics and control.
Why do not use s2i service shipped with openshift ?
Regards.
I have followed this guide from Google documentation in order to be able to push a custom Docker image to Google Container Registry and then be able to start a new GCE instance with this image. At first I wanted to try using an anaconda3 public image from docker hub without any modification (in order to test).
So here is the steps I have done so far after installing gcloud and docker:
gcloud auth configure-docker -> configured docker with my gcloud crendentials
docker pull continuumio/anaconda3 -> pulled the public image
docker tag continuumio/anaconda3 eu.gcr.io/my-project-id/anaconda3 -> tagged the local image with the registry name as specified in the doc
docker push eu.gcr.io/my-project-id/anaconda3 -> pushed the image to GCR
Good ! I am now able to see my image trough GCR interface, and also able to deploy it with GCE. I choose to deploy it with a f1-micro instance, Container-Optimized OS 67-10575.62.0 stable, 10 Go boot disk, Allow HTTP traffic, etc.
But when I connect with ssh to the freshly new created VM instance, I can't find anaconda3 librairies (which are supposed to be created in /opt/conda). Instead, I can see a /opt/google directory which makes me think that the image has not been deployed correctly and GCE is using a default image...
So I tried to check if the image was pushed correctly in GCR, so I decided to delete my local image and pull it once again from GCR:
docker rmi -f eu.gcr.io/my-project-id/anaconda3
docker pull eu.gcr.io/my-project-id/anaconda3:latest
I run the image
docker run -t -i eu.gcr.io/my-project-id/anaconda3
and I can see that everything is fine, I have anaconda3 installed correctly inside /opt/conda with all the toolts needed (Pandas, Numpy, Jupyter notebook, etc.)
I tried to find people with the same problem as me without any success... maybe I have done something wrong in my proccess ?
Thanks !
TL;DR My problem is that I have pushed an anaconda3 image on Google GCR, but when I launch a virtual instance with this image, I do not have anaconda on it
It's normal that you can't find anaconda libraries installed directly on the GCE instance.
Actually, when you choose to deploy a container image on a GCE VM instance, a Docker container is started from the image you provide (in your example, eu.gcr.io/my-project-id/anaconda3). The libraries are not installed on the host, but rather inside that container (run docker ps to see it, but normally it has the same name as your VM instance). If you run something like :
docker exec -it <docker_container_name> ls /opt/conda
Then you should see the anaconda libraries, only existing inside the container.
When you run docker run -t -i eu.gcr.io/my-project-id/anaconda3, you're actually starting the container and running an interactive bash session inside that container (see the CMD here). That's why you can find anaconda libraries : you are inside the container!
Containerization software (docker here) provides isolation between your host and your containers. I'll suggest you to read documentation about containerization, Docker and how to run containers on Container-Optimized OS.
I have an Image which i should add a dependency to it. Therefore I have tried to change the image when is running on the container and create new Image.
I have follow this article with the following commands after :
kubectl run my-app --image=gcr.io/my-project-id/my-app-image:v1 --port 8080
kubectl get pods
kubectl exec -it my-app-container-id -- /bin/bash
then in the shell of container, i have installed the dependency using "pip install NAME_OF_Dependncy".
Then I have exited from the shell of container and as it have been explained in the article, i should commit the change using this command :
sudo docker commit CONTAINER_ID nginx-template
But I can not find the corresponding command for Google Kubernetes Engine with kubectl
How should i do the commit in google container engine?
As with K8s Version 1.8. There is no way to do Hot Fix changes directly to the images.For example, Committing new image from running container. If you still change or add something by using exec it will stay until the container is running. It's not best practice in K8s eco-system.
The recommended way is to use Dockerfile and customise the images according to the necessity and requirements.After that, you can push that images to the registry(public/ private ) and deploy it with K8s manifest file.
Solution to your issue
Create a Dockerfile for your images.
Build the image by using Dockerfile.
Push the image to the registry.
write the deployment manifest file as well service manifest file.
apply the manifest file to the k8s cluster.
Now If you want to change/modify something, you just need to change/modify the Dockerfile and follow the remaining steps.
As you know that containers are a short living creature which does not have persist changed behaviour ( modified configuration, changing file system).Therefore, It's better to give new behaviour or modification at the Dockerfile.
Kubernetes Mantra
Kubernetes is Cloud Native product which means it does not matter whether you are using Google Cloud, AWS or Azure. It needs to have consistent behaviour on each cloud provider.