Migrating services with zero downtime using EFS and lsyncd
Today, I want to talk about a situation that I found myself in recently. I have a production mail server that I had to migrate recently, as the OS version was getting quite out of date. Unfortunately, when I stood the server up, I didn't plan on ever migrating - so I set everything up using local storage.
Adding SpamAssassin filtering to your mail server
Last week, I finally decided it was time to move forward with getting all of my mail self-hosted. I'd been using my mail server primarily for sending automated messages, but my previous mail service was really limiting me in terms of what I was able to do, so I finally bit the bullet and went for it.
Amazon now allows IAM roles to be attached to existing EC2 instances
Just wanted to dash off a quick note. Amazon Web Services announced last week that you can now add IAM roles to your existing EC2 instances. This means you won't have to recreate an instance in order to attach a role - now, you can use my tutorial on sending backups of your EC2-hosted data to S3 on instances you've already created, and not just new instances.
Creating S3 backups of EC2 data in the AWS cloud
As part of my switch over to the AWS cloud and specifically EC2 after my physical server started having issues, I wanted to make sure that I had reliable, consistent backups. Amazon provides a great solution for this in the form of Amazon S3, a service that provides eleven 9's of durability for stored data.
A definitive Postfix/Dovecot mail server guide
My physical server finally bit the dust last month, so I finally took the opportunity to move up to the Amazon Web Services cloud. In the process of building my new cloud server, I realized I needed to get a mail server working - but I hadn't ever built out a Linux mail server before past the very basics of configuring Postfix.
How to set up 2FA on your CentOS server
Recently, I was looking into (casually, as an experiment) setting up two-factor authentication on CentOS 7, using Google Authenticator. All of the articles out there right now are kind of out of date, though, so I figured I’d walk through the process from an “it worked for me” perspective so that everyone has an updated reference in 2016.
An easy dedicated syslog server
Recently, I had the need to put together a centralized internal logging server. While the growth of external monitoring services like Logglyor Sumo Logicis awesome (and trust me, I’m not arguing this point – I use both of these services extensively myself!), centralized syslog is still the best solution in some use cases.
Enable cross-origin requests in Zabbix
Recently, I received a couple of requests asking about how to get zabbixwebworking on an external server, as by default you can’t hit the Zabbix API from external servers on both the appliance downloaded from the Zabbix site and the default install on RHEL-based Linux servers. I looked back at my original blog post, and sure enough, I forgot to explain how to do that!
Multiple-site configuration for Varnish Server
Recently, I started looking into building a Varnish server that could handle multiple websites, possibly running multiple frameworks. I knew that it was possible to include extra VCL’s based on hostname as seen on the Varnish Software blog, but when I tried to implement that in my config, I kept on getting errors.
Resolving EPEL 404 errors (yum errno 14)
Today, I ran into an interesting issue with yum where I was unable to contact EPEL repository mirrors – every mirror was throwing “filelists.sqlite.xz: [Errno 14] HTTP Error 404 – Not Found”. I tried uninstalling and reinstalling the epel-release package, but that didn’t help. It turns out that this issue is caused by cached data in yum and can sometimes happen when repos update.
How to install Symantec Backup Exec Agent on CentOS/RHEL 7 Minimal
Recently, I was helping evaluate new long-term backup options to replace Microsoft’s DPM due to their lack of support for Linux, and one of the options that we were looking at was Symantec Backup Exec 2014. Unfortunately, if you look at their software compatibility list, you’ll notice that they do support Red Hat 7, but with a very important caveat – you can’t install as minimal.
Installing Varnish 3 on CentOS 7
Oddly, there isn’t a lot of information on installing Varnish 3 on CentOS 7. There’s well-written instructions on the official site for CentOS 5/6, but for 7, it seems like you’re stuck with Varnish 4 (from the epel-release repository), especially if you’ve searched around and found forum threads like this one.
Installing Apache 2.4 with PHP 5.4 on CentOS 6.5
Recently, we were looking into how to install Apache 2.4 and PHP 5.4 with PHP-FPM on our CentOS boxes, as PHP 5.3 with Apache 2.2 was feeling a bit outdated. Since CentOS 7 isn’t quite out yet, we put together a process to install these on our CentOS 6.5 servers (Update: Now that CentOS 7 is out, the process is a lot more straightforward: just run yum install httpd php php-fpm.
Putting the “fast” back in FastInviter
I’ve been developing a new tool recently. It’s called FastInviter, and is publicly available at both its website as well as in a GitHub repository. I’ve been having a lot of fun developing it, but I hit a big snag along the way that made it seem…well, more like SlowInviter, to be honest.