Smokeping Failing to Start on Boot (Fedora 24)

I ran into an issue where smokeping wasn’t starting on boot on my fedora 24 systems. Checking the output of:

systemctl status smokeping

Showed me that dns requests were failing and smokeping terminated. So here’s how I fixed it.

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SSSD, AD UNIX Attributes, and SSH AllowGroups

So  I recently ran into an issue where we had the following setup:

  • Active Directory Domain
  • Realm joined RHEL 7 Hosts
  • A requirement for UNIX Attributes set in AD
  • sshd_config AllowGroups restrictions

However, the RHEL 7 hosts were not able to display  secondary/supplementary groups in AD when running id and thus, AllowGroups in sshd was failing.

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Break/Fix: Varnish 4 and Apache Vhosts

I spent about an hour scratching my head trying to figure out why my name based vhosts stopped working in Apache 2.4 after I setup Varnish. The answer was quite simple and I will freely admit my embarrassment in case it saves anyone else some time:

Don’t forget to update your vhosts so that this:

<VirtualHost *:80>

Looks like:

<VirtualHost *:8080> <substitute 8080 for whatever port you configured apache to listen on>

You’ll then need to reload your Apache config. Common sense, but it can be often overlooked.

How-to: Basic HAProxy Active/Backup Example Configuration (keepalived) for CentOS/RHEL 6

I had an earlier post regarding a basic HAProxy install that will work fine if your site(s) can tolerate some down time should something happen to your server/instance running HAProxy. While this might be acceptable for a personal site, it quickly becomes unacceptable should your business rely on your site being up without interruption. Luckily for you, it’s relatively simple to configure an HA pair of HAProxy load balancers.

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Break/Fix: RPM rpmdb: Lock table is out of available locker entries

The full error may look something like this:

-------------------------------------------------------------------------
    rpmdb: Lock table is out of available locker entries
    error: db4 error(22) from db->close: Invalid argument
    error: cannot open Packages index using db3 - Cannot allocate memory (12)
    error: cannot open Packages database in /var/lib/rpm
-------------------------------------------------------------------------

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How-to: Basic HAProxy Example Configuration for CentOS/RHEL 6

This is a basic HAProxy configuration example that should get you up and running with the simplest of setups. This configuration will have the HAProxy Info page listening on 8080 (adjust as needed) with username/password authentication. In addition, it will also look for http://yourip/healthcheck in addition to the TCP 80 HTTP Port Probes. Why is this useful?

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How-to: Switching WordPress from MySQL 5.1 to MariaDB 5.5 on CentOS/RHEL 6

Recently, I was somewhat bored and decided to switch from a MySQL 5.1 backend to MySQL 5.5 for my site (of which you have the distinct pleasure of reading).  While doing a little Googling,  I remembered MariaDB. MariaDB is marketed as “An enhanced, drop-in replacement for MySQL”, so I figured why not give it a shot?

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Break/Fix: WordPress Permalinks 404 Issue

I recently ran into an issue in which changing the permalinks setting in WordPress resulted in 404 pages across my site. I checked my WordPress root dir and the proper .htaccess file was there with the proper permissons, but permalinks refused to work. It turned out to be a quick fix and a case of “Doh! Stupid mistake on my part”.

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