CentOS vs CoreOS – Which OS to choose for your Docker web hosting services

While Docker was conceived only as a PaaS solution, web hosts are now realizing Docker’s potential in specialized application hosting such as WordPress hosting.

As a Server Management company, we are often asked what is the right OS for Docker hosting. CentOS is popular in web hosting industry, while CoreOS is used by many in the Docker ecosystem.

To decide which OS fares better for application hosting, let’s take a look at the different challenges faced by web hosts, and how well each OS fares in tackling them.

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1. Uptime and availability – CoreOS has built-in high availability

Uptime is important for web hosts. Many high availability solutions exist in the market, but they are either too costly to implement or difficult to maintain.

CoreOS has a built-in feature called “fleet” that helps setup high availability. With fleet it is possible to spread out production services (such as Web, Database, etc.) across multiple servers. So, even if one server fails, the service keeps running from other servers.

CoreOS vs CentOS - HA using clustering

Even if CoreOS server 2 fails, the web servers in Server 1 and 2 continue serving the site.

A similar functionality is possible in CentOS using a Docker feature called “Docker Swarm”. However, it is not as customizable as a CoreOS-fleet system. You have to live with whatever options Docker provides, and custom configuration can be hard.

Now, it would seem that just using fleet or Docker Swarm would ensure high availability. Well, not exactly. In either case there are system requirements such as resource availability, flawless cluster connection, and seamless network re-routing that should work for high availability to be possible.

At Bobcares, we minimize the risk of a cluster failure by monitoring our customer network 24/7, and by quickly fixing any connection or resource anomalies. And to un-cover any hidden HA issue, we test the fail-over systems periodically. Cumulatively, these precautions make sure that our customers have a highly reliable HA solution.

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2. Server security – CoreOS has the edge

Hackers gain access to systems by exploiting vulnerabilities (aka bugs) in server software. The bigger the software, the greater is the chance for a bug in it. CoreOS minimizes this “surface area of attack” by limiting it’s size to 260 MB. In comparison, CentOS is 4 GB in size.

CoreOS vs CentOs - Size difference

It is not to say that CoreOS is hack proof. Like any other system, it must be configured to be secure, monitored for anomalies, and maintained professionally.

In the CoreOS and CentOS servers that we manage for our customers, we setup strong firewall rules, monitor server events 24/7 to detect hack attempts and audit the server periodically to make sure everything is locked down tight.


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