Creating a simple Linux cluster doesn’t have to be complicated. Below, I demonstrate how to do so with keepalived, named, and nginx. The clustered service will be nginx. I will use named to return virtual IPs (VIP)s when clients lookup the name of the clustered services. Keepalived will be used to manage VIP failover. Server… Read More »
Mirroring an Existing LVM Volume is pretty straightforward. Assuming you have enough space for it on separate physical volumes, it is a single command. According to the documentation, you will find two varieties. One is just called mirror, the other raid1. The documentation recommends using raid1, so that is what I will cover. There are… Read More »
There may be occasions where you need to remove an LVM disk. Maybe the host is a VM and you need space on the hypervisor? Perhaps the device is a fiber channel SAN target that you no longer need? No matter the reason, it isn’t terribly difficult to remove an LVM disk. There are three… Read More »
There are a few good reasons for setting up an HAProxy LDAP backend. Perhaps the client’s TLS implementation is lacking. Maybe the application only supports a single server and you can’t afford down time. In the latter scenario, setting up multiple address records in DNS with the same domain name. The problem with that is… Read More »
I am assuming you just increased the size of a disk on a virtualization platform such as VMware or VirtualBox. Perhaps it is a SAN device. Either way, you will follow the same process. If your machine is on a SAN or it is a virtual machine running on a hypervisor that supports online resizing,… Read More »
This guide will walk you through setting up CentOS 8 to use an LDAP directory server for authentication. I am assuming you have a directory server up and running. If you don’t, you can follow these two guides to install and configure OpenLDAP: Install OpenLDAP From Source – CentOS 8 Configure OpenLDAP In this guide,… Read More »
With both DNF and YUM, there are three ways to remove repositories. One of the methods is specific to RHEL. If you are on a system that doesn’t have the dnf command, you can use the yum command instead. Using subscription-manager The subscription-manager program is specific to RHEL and specific to repositories maintained by Red… Read More »
There are a few ways to add a user to a group in Linux. I will cover two methods using the command line. Both methods require the ability to use the root account or the sudo command. Desktop environments often have GUI tools to do this. If you wish to use the GUI, check your… Read More »
To add a user to sudoers, edit the file /etc/sudoers. Many systems come with a /etc/sudoers file that gives permission to a specific group. If your /etc/sudoers has a line that looks like one of these, you can allow a user to use sudo by adding the user to that group. %sudo ALL=(ALL:ALL) ALL %sudo… Read More »
The OpenLDAP audit log overlay is used to track changes to a database. It stores its data in an LDIF file. On busy servers, consider setting up a cron job to automatically rotate, compress, or archive the log file. Setting up the OpenLDAP audit log overlay is pretty straightforward. There are only a few steps… Read More »