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1-Minute Multi-Node VM Setup

by Ian MiellDecember 8th, 2016

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Quickly spin up multiple VMs with useful DNSs on your local machine and automate complex environments easily.

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tl;dr

Quickly spin up multiple VMs with useful DNSs on your local machine and automate complex environments easily.

Here’s a video:

Multinode VM Setup_Recorded by ianmiell_asciinema.org

Introduction

Maintaining Docker at scale, I’m more frequently concerned with clusters of VMs than the containers themselves.

The irony of this is not lost on me.

Frequently I need to spin up clusters of machines. Either this is very slow/unreliable (Enterprise OpenStack implementation) or expensive (Amazon).

The obvious answer to this is to use Vagrant, but managing this can be challenging.

So I present here a very easy way to set up a useful Vagrant cluster. With this framework, you can then automate your ‘real’ environment and play to your heart’s content.

$ pip install shutit$ shutit skeleton

# Input a name for this module.# Default: /Users/imiell/shutit_resins

[hit return to take default]

# Input a ShutIt pattern.Default: bashbash: a shell scriptdocker: a docker image buildvagrant: a vagrant setupdocker_tutorial: a docker-based tutorialshutitfile: a shutitfile-based project

[type in vagrant]

vagrant

How many machines do you want (default: 3)? 3

[hit return to take default]

What do you want to call the machines (eg superserver) (default: machine)?

[hit return to take default]

Do you want to have open ssh access between machines? (default: yes) yes

Initialized empty Git repository in /Users/imiell/shutit_resins/.git/Cloning into ‘shutit-library’...remote: Counting objects: 1322, done.remote: Compressing objects: 100% (33/33), done.remote: Total 1322 (delta 20), reused 0 (delta 0), pack-reused 1289Receiving objects: 100% (1322/1322), 1.12 MiB | 807.00 KiB/s, done.Resolving deltas: 100% (658/658), done.Checking connectivity… done.

# Run:cd /Users/imiell/shutit_resins && ./run.shto run.

[follow the instructions to run up your cluster.

$ cd /Users/imiell/shutit_resins && ./run.sh

This will automatically run up an n-node cluster and then finish up.

NOTE: Make sure you have enough resources on your machine to run this!

BTW, if you re-run the run.sh it automatically clears up previous VMs spun up by the script to prevent your machine grinding to a halt with old machines.

Multinode VM Setup_Recorded by ianmiell_asciinema.org

Going deeper

What you can do from there is automate the setup of these nodes to your needs.

For example:

def build(self, shutit):[... go to end of this function ...]

# Install apacheshutit.login(command='vagrant ssh machine1')shutit.login(command='sudo su - ')shutit.install('apache2')shutit.logout()shutit.logout()

# Go to machine2 and call machine1's servershutit.login(command='vagrant ssh machine2')shutit.login(command='sudo su -')shutit.install('curl')shutit.send('curl machine1.vagrant.test')shutit.logout()shutit.logout()

Will set up an apache server and curl a request to the first machine from the second.