Using Vagrant to Emulate Rancher Environments

I spend a large amount of my time helping clients implement Rancher successfully. As Rancher is involved in just about every vertical, I come across a large number of different infrastructure configurations, including (but not limited to!) air-gapped, proxied, SSL, HA Rancher Server, and non-HA Rancher Server.

Scenario & Criteria

What I wanted was a way to quickly emulate an environment to allow me to more closely test or replicate an issue. Now this could be done in a number of ways, but the solution I wanted had to meet the following criteria:

  • Run locally — Yes, it can be done in the cloud, but running services in the cloud costs money, so I wanted to keep the cost down.
  • Be local host OS agnostic — So others can use it, I didn’t want to tie it to Windows, MacOS or Linux.
  • Emulate multiple infrastructure scenarios — As in the criteria above, but I must also be able to use it as a basis for doing local application development and testing of containers.
  • Minimise bandwidth
  • Be easy to configure — So that anyone can use it.

The Solution

To fulfill the first two criteria, I needed a hypervisor (preferably free) that could run on all platforms locally. Having had a reasonable amount of experience with VirtualBox (and it meeting my preferably free criterion), I decided to use it. The third criterion was to allow me to emulate environments locally that had the following configurations:

  • Air gap — Where there was no connection to the internet to install Rancher Server and nodes
  • Proxied — Where the Internet access was via a proxy server
  • SSL — Where the connection to the Rancher Server SSL terminated
  • HA — The ability to stand up Rancher Server in a HA configuration with an externalized database and a configurable number of nodes

To meet the fourth criterion to minimise bandwidth, I decided to run a registry mirror. It allowed me to destroy the setup and start afresh quickly as all the VMs had Docker engine set to pull via the mirror. Not only does it save bandwidth, but it also significantly speeds up rebuilds. Files for the mirror persist to the local disk to preserve them between rebuilds. For the final criterion of easy configuration, I decided that I was going to use Vagrant. For those reading who haven’t used Vagrant:

  • It’s open-source software that helps you build and maintain portable, virtual software development environments.
  • It provides the same, easy workflow regardless of your role as a developer, operator, or designer. It leverages a declarative configuration file which describes all your software requirements, packages, operating system configuration, users, and more.
  • It works on Mac, Linux, Windows, and more. Remote development environments force users to give up their favorite editors and programs. Vagrant works with tools on your local system with which you’re already familiar.

After you download Vagrant, you can specify that it consumes its config from a separate file. For this setup, all configurable options are externalized into a config.yaml file that is parsed at startup. This means that you can configure and use it without having to have a deep, technical understanding of Vagrant. I also added an NFS server to the solution, running on the master node so that services could be tested with persistent storage. So, what does the final solution look like? The master node runs a bunch of supporting services like MYSQL and HAProxy to help all of this hang together. In true Docker style, all of these supporting services are containerised!

Minimum Setup

To run this solution, the setup will create a minimum of three VMs. There is a master, a minimum of one Rancher Server, and one node. Below is an example of the config.yaml file with the main parts that you will change highlighted: You can find more detail on the config options in our repository for this setup.

Quick Start

For those of you wanting a Quick Start, you need the following software installed:

Then, it is as simple as dropping to a command prompt and running the following commands:

git clone https://github.com/rancher/vagrant
cd vagrant
vagrant up

Rancher Server will start running Cattle with three nodes. This Quick Start also supports Rancher 2.0, so if you want to check out the Tech Preview with the minimum of effort, run:

git clone https://github.com/rancher/vagrant
cd vagrant
git checkout 2.0
vagrant up

Thanks to my colleague James, for helping me enhance this solution to what it has become.

About the Author

Chris Urwin works as a field engineer for Rancher Labs based out of the UK. He spends his days helping our enterprise clients get the most out of Rancher, and his nights wishing he had more hair on his head!

快速开启您的Rancher之旅