Book Image

Learning CoreOS

By : Kingston Smiler. S, Shantanu Agrawal
Book Image

Learning CoreOS

By: Kingston Smiler. S, Shantanu Agrawal

Overview of this book

CoreOS is an open source operating system developed upon the Linux kernel. The rise of CoreOS is directly related to the rise of Docker (a Linux container management system). It is a minimal operating system layer and takes a different approach to automating the deployment of containers. The major difference between CoreOS and other Linux distributions is that CoreOS was designed to deploy hundreds of servers. CoreOS immensely helps the users to create systems, which are easy to scale and manage, making life easier for all, be it developer, QA, or deployer. This book is all about setting up, deploying, and using CoreOS to manage clusters and clouds. It will help you understand what CoreOS is and its benefits as a cloud orchestration platform. First, we’ll show you how to set up a simple CoreOS instance with single node in the cluster and how to run a Docker container inside the CoreOS instance. Next, you’ll be introduced to Fleet and systemd, and will deploy and distribute Docker services across different nodes in cluster using Fleet. Later, you’ll be briefed about running services in a cluster with constraints, publishing the services already running on the cluster to new services, and making your services interact with each other. We conclude by teaching you about advanced container networking. By the end of the book, you will know the salient features of CoreOS and will be able to deploy, administrate, and secure a CoreOS environment.

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Learning CoreOS
Kingston Smiler. S | Shantanu Agrawal
Mar, 2016 | 190 pages
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Table of Contents (15 chapters)
Learning CoreOS
Learning CoreOS
Credits
Credits
About the Authors
About the Authors
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
CoreOS, Yet Another Linux Distro?
CoreOS, Yet Another Linux Distro?
Introduction to CoreOS
CoreOS versus other Linux distributions
CoreOS high-level architecture
CoreOS and OpenStack
Summary
2
Setting Up Your CoreOS Environment
Setting Up Your CoreOS Environment
Installing GIT
Installing VirtualBox
Introduction to Vagrant
Setting up CoreOS on VMware vSphere
Installing VMware vSphere Client
Introduction to Docker
Summary
3
Creating Your CoreOS Cluster and Managing the Cluster
Creating Your CoreOS Cluster and Managing the Cluster
Introduction to clustering
The why and the benefits of clustering
CoreOS clustering
Summary
4
Managing Services with User-Defined Constraints
Managing Services with User-Defined Constraints
Introduction to service constraints
Predefined constraints using metadata
Summary
5
Discovering Services Running in a Cluster
Discovering Services Running in a Cluster
Introduction and necessity of service discovery
Mechanism for service discovery
HAProxy and service discovery
Summary
6
Service Chaining and Networking Across Services
Service Chaining and Networking Across Services
Introduction to and necessity of service chaining
Introduction to Docker networking
Introduction to Weave
Introduction to Flannel/Rudder
Integrating Flannel with CoreOS
Summary
7
Creating a Virtual Tenant Network and Service Chaining Using OVS
Creating a Virtual Tenant Network and Service Chaining Using OVS
Introduction to OVS
Introduction to overlay and underlay networks
Introduction to network virtualization
Running OVS in CoreOS
Summary
8
What Next?
What Next?
Container security
Update and patches – CoreUpdate
Dex
sysdig
Competitive container orchestration mechanism
Apache-Mesos
Swarm
Docker data volume management
Open Container Project
Summary
Index
Index

CoreOS and OpenStack

Is CoreOS yet another orchestration framework like OpenStack/CloudStack? No, it is not. CoreOS is not a standalone orchestration framework like OpenStack/CloudStack. In most server orchestration frameworks, the framework sits external to the managed cloud. But in CoreOS, the orchestration framework sits along with the existing business solution.

OpenStack is one of the most widely used cloud computing software platforms to provide IaaS. OpenStack is used for orchestrating the compute, storage, and network entities of the cloud, whereas CoreOS is used for service orchestration. Once the compute, storage, or network entities are instantiated, OpenStack doesn't have any role in instantiating services inside these VMs.

Combining the orchestration provided by OpenStack and CoreOS provides a powerful IaaS, wherein the cloud provider will have fine-grained control until the service orchestration. So CoreOS can co-exist with OpenStack, wherein OpenStack can instantiate a set of VMs that run the CoreOS instance and form a CoreOS cluster. That is, OpenStack can be used to create a CoreOS cluster as infrastructure. The CoreOS that is running inside the VM forms as a cluster and instantiates the service inside any one of the nodes in the cluster.

OpenStack and CoreOS

In the preceding diagram, OpenStack is used to manage the server farm that consists of three servers: server1, server2, and server3. When a customer is requested for a set of VMs, OpenStack creates the necessary VM in any one of these servers, as an IaaS offering. With CoreOS, all these VMs run the CoreOS image with the same cluster ID, and hence can be part of the same cluster. In the preceding diagram, there are two CoreOS clusters, each allocated for different customers. The services/applications to be run on these VMs will be instantiated by the fleet service of CoreOS, which takes care of instantiating the service in any one of the VMs in the cluster. At any point in time, OpenStack can instantiate new VMs inside the cluster in order to scale up the cluster capacity by adding new VMs running the CoreOS image with the same cluster ID, which will be a candidate for CoreOS to run new services.

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