Tag: Series: CoreOS Overview
12 Feb 2016 in Series: CoreOS Overview, CoreOS, Overview

CoreOS Overview, Part Three

This post is available in: Chinese`

This is the third and final post in a series looking at CoreOS.

In my last post, we looked at the cloud-config file, running etcd in proxy mode, and some common etcd cluster setups.

In this post, we take a closer look at systemd, unit files, Fleet, and fleetctl.

systemd Overview

systemd is an init system used by CoreOS that provides many powerful features for starting, stopping, monitoring, and restarting process. On CoreOS, systemd is used to manage the lifecycle of your Docker containers and also for different system bootstrap tasks.

Learning systemd would need a series of blog posts in itself. Here we only cover systemd to the extent that we need to run systemd units for Docker containers on CoreOS.

For more information about systemd, see the documentation.

Read More
5 Feb 2016 in Series: CoreOS Overview, CoreOS, Overview

CoreOS Overview, Part Two

This post is available in: Chinese`

This is the second post in a series looking at CoreOS.

In my last post, we looked at how CoreOS is different from other Linux systems, atomic upgrades and release channels, and the basics of cluster discovery.

In this post, we take a closer look at cloud-config and etcd. We'll also look at a few common cluster architectures.

Cloud-Config

Cloud-config allows you to declaratively customize various OS-level items, such as network configuration, user accounts, and systemd units (which we'll cover the next post). This came from Ubuntu and was modified a bit to fit the needs of CoreOS.

At the core of every CoreOS cluster machine, there is the bootstrap mechanic coreos-cloudinit. The coreos-cloudinit program the cloud-config file when it configures the OS after startup or during runtime.

Read More
29 Jan 2016 in Series: CoreOS Overview, CoreOS, Overview

CoreOS Overview, Part One

This post is available in: Chinese

CoreOS is an important part of many container stacks. In this series of posts, we’re going to take a look at CoreOS, why it’s important, and how it works. If you don’t know anything about CoreOS already, don’t worry. We start at the beginning.

The Basics and How CoreOS Is Different From Other Linux Systems

CoreOS is designed for security, consistency, and reliability.

  • Automatic CoreOS updates are done using an active/passive dual-partition scheme to update CoreOS as a single unit, instead of using a package-by-package method. We go over this in detail later.
Read More