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spacewalk-k8s

Spacewalk--containerized and running on Kubernetes

https://jacobsalmela.com/2019/02/18/spacewalk-containerized-and-running-in-kubernetes/

Pull prebuilt images from Github or Docker

# Github
docker pull docker.pkg.github.com/jacobsalmela/spacewalk-k8s/spacewalk:2.10
docker pull docker.pkg.github.com/jacobsalmela/spacewalk-k8s/spacewalk-postgres:2.10
# Docker
docker pull jacobsalmela/spacewalk:2.10
docker pull jacobsalmela/spacewalk-postgres:2.10

Spacewalk as a Kubernetes deployment, why?

This repo is an attempt to containerize Spacewalk and run it as a Kubernetes deployment.

I started doing this because Spacewalk is a monolithic app and upgrading it is difficult. It also takes a while to setup, so recovering from a disaster would be slow. I fell in love with Kubernetes and I thought Spacewalk was the perfect candidate for a container because:

  • it is a monolithic app with several components that can be broken down into microservices
  • it is difficult to upgrade parts of the software without updating everything
  • some might consider it a legacy app because the only way to install it is via a traditional install directly to an OS so it's not very future proof

I also wanted to show how it is possible to take a complex program and containerize it, even though it is not easy. So this repo:

  • demonstrates how you can decouple parts of the program, like the database and turn it into it's own container
  • demonstrates how to take a traditional app that runs on an init system and port it over to a container
  • demonstrates how to create config maps
  • demonstrates how to create custom docker images from parts of an existing application
  • demonstrates how to use persistent volumes for data that needs to persist

Caveats

The Dockerfile does most everything, but the last program supervisord runs is a sleep command and then installs Spacewalk and restarts the Web services. It's janky, but it seems to work--at least for development. It also seems to work fine if you kill the deployment and re-create it--the persistent storage portion is working so you don't lose anything.

Testing locally

git clone <this repo>
cd <this repo>
docker build -t spacewalk:2.10 -f Dockerfile-centos .
cd postgres/
docker build -t spacewalk-postgres:2.10 .
cd ..
kubectl create -f spacewalk-pv/
kubectl create -f spacewalk/
kubectl get po
kubectl port-forward <pod> 8000:80 8443:443 8080:8080

(optionally) enter the container and run a few more commands:

kubectl exec -it <CONTAINER ID> /bin/bash

# Make sure this program is exited
supervisorctl status spacewalk-init
# If it's running forever, stop it and start it again
supervisorctl stop spacewalk-init
supervisorctl start spacewalk-init
# Or run the install commands yourself from the supervisord config map

At this point, you should be able to reach the Web interface.

https://127.0.0.1:8443/rhn/newlogin/CreateFirstUser.do

or https://127.0.0.1:8443/rhn/Login.do if you already created your first user account and have an existing database.

Register a client

I tested with a container here as an example, but the steps are the same for a traditional server or VM (per https://github.com/spacewalkproject/spacewalk/wiki/RegisteringClients#red-hat-enterprise-linux-5-6-and-7-scientific-linux-6-and-7-centos-5-6-and-7)

rpm -Uvh https://copr-be.cloud.fedoraproject.org/results/%40spacewalkproject/spacewalk-2.10/epel-7-x86_64/01259466-spacewalk-repo/spacewalk-client-repo-2.10-8.el7.noarch.rpm
rpm -Uvh http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
yum -y install rhn-client-tools rhn-check rhn-setup rhnsd m2crypto yum-rhn-plugin
rpm -Uvh http://<SPACEWALK WEB CONTAINER>/pub/rhn-org-trusted-ssl-cert-1.0-1.noarch.rpm
rhnreg_ks --serverUrl=https://<SPACEWALK WEB CONTAINER>/XMLRPC --sslCACert=/usr/share/rhn/RHN-ORG-TRUSTED-SSL-CERT --activationkey=1-centos7

Re-deploying with changes

You can rebuild images if you make changes. Thanks to the persistent storage, the database and things should stay in tact.

kubectl delete -f spacewalk/
kubectl create -f spacewalk/

Just don't delete the spacewalk-pv/ folder or you'll lose your persistent storage.

Exploring the database

I have included the adminer container, which is a nice little GUI for databases. Load it up at http://localhost:8080

Next steps