CentOS Remove Old Kernels

Tonight when upgrading a CentOS Linux server it was noted by YUM that 15MB more disk space was needed to upgrade grub and the kernel itself. Below are four quick steps to verify what kernels are installed, install yum-utils if it is not installed already, delete previous kernels and set YUM to remove old kernels…

Technology Errors

RightScale Stop Recipe From Being Used In RightScript, GIT /tmp/ssh.key.sh

If you have created a custom RightScript in the RightScale interface that uses git to clone a repository and you are running that RightScript on boot following the RightScale git_repo recipe then you likely are having issues. The problem appears to stem from the fact that the environment variables are not completely cleaned up as expected including $GIT_SSH and possibly others. I have a work around noted below along with a line you can enter in your RightScript to clear the $GIT_SSH ENV variable as well.

Code Snippets

RightScale RightScript To Add SSH Users To Linux Nodes On Boot

The below code snippet was used to add SSH users to RackSpace cloud CentOS Linux nodes being used as application servers and managed via RightScale. The SSH users were required during a testing phase so they could look through logs and make modifications to specific configuration files, etc. There are three things that have to happen to create the SSH user, allow them to login, and provide them the necessary rights on the server to accomplish their tasks which include adding the user, modifying the sshd config to allow password logins, and update the sudoers file to enable sudo access for wheel group users.

Code Snippets

Restart Services On RackSpace Managed Nodes That Require sudo Rights

Recently I was working on a project that was using RightScale to manage RackSpace cloud nodes. One of the requirements of the project was to have application nodes scale automatically thus they were required to automatically install software, configure settings, and start services automatically on the RackSpace CentOS nodes being used. Most everything was fairly straight forward however some of the services we were using would not start properly and initially because of the lack of logging from the services we were unable to figure out what the problem was. Below I describe the problem in more detail along with the solution which involved updating a configuration file on the CentOS Linux servers and then restarting the services.