dev-lxc

dev-lxc builds and manages clusters of LXC containers and includes the ability to install and configure Chef products.

Cluster management includes the ability to manage snapshots of the containers which makes dev-lxc well suited as a tool for support related work, customized cluster builds for demo purposes, as well as general experimentation and exploration.

Features

  1. LXC 2.0 Containers - Resource efficient servers with fast start/stop times and standard init
  2. Btrfs - Efficient, persistent storage backend provides fast, lightweight container snapshots
  3. Dnsmasq - DHCP networking and DNS resolution
  4. Base Containers - Containers that are built to resemble a traditional server
  5. ruby-lxc - Ruby bindings for liblxc
  6. YAML - Simple, flexible definition of clusters
  7. Build process closely follows online installation documentation
  8. Snapshots - Snapshots are created during the cluster's build process which makes rebuilding a cluster very fast.
  9. mixlib-install library - Automatically manages a cache of Chef products

Its containers, standard init, networking and build process are designed to be similar to what you would build if you follow the online installation documentation so the end result is a cluster that is relatively similar to a more traditionally built cluster.

The Btrfs backed snapshots provide a quick clean slate which is helpful especially for experimenting and troubleshooting. Or it can be used to build a customized cluster for demo purposes and be able to bring it up quickly and reliably.

If you aren't familiar with using containers please read this introduction.

LXC 1.0 Introduction

Requirements

When you are done with the prerequisites you should be able to log into the dev-lxc-platform VM and start using it.

You must login to the root user to use the dev-lxc command.

cd dev-lxc-platform
vagrant ssh
sudo -i

Update dev-lxc gem

Run the following command if you ever need to upgrade the dev-lxc gem inside the dev-lxc-platform VM.

chef gem update dev-lxc

Display Help

dev-lxc help

dev-lxc help <subcommand>

dev-lxc Alias and Subcommands

The dev-lxc command has a dl alias for ease of use.

You only have to type enough of a dev-lxc subcommand to make it unique.

For example, the following commands are equivalent:

dev-lxc status
dl st

dev-lxc snapshot
dl sn

Demo: Build Chef Automate Cluster

Log into the dev-lxc-platform VM's root user.

cd dev-lxc-platform
vagrant up     # if the VM is not already running
vagrant ssh
sudo -i

When you are logged in as the root user you should automatically enter a byobu session.

Byobu makes it easy to manage multiple terminal windows and panes. You can press fn-F1 to get help which includes a list of keybindings.

Some of the keys that will be most useful to you are:

  • option-Up, option-Down to switch between Byobu sessions
  • option-Left, option-Right to switch between windows in a session
  • shift-Left, shift-Right, shift-Up, shift-Down to switch between panes in a window

Create Base Container

The base container used for the cluster's containers must be created first. Let's use Ubuntu 14.04 for the base container.

dl create b-ubuntu-1404

Create Config File

Create the dev-lxc.yml config file for the cluster.

First, create an arbitrary directory to hold the dev-lxc.yml file.

mkdir -p /root/work/clusters/automate

Then use the init subcommand to generate a sample configuration using the available options. Run dl help init to see what options are available.

The following command configures a standalone Chef Server, a Chef Automate server and a build node.

dl init --chef --automate --build-nodes -f /root/work/clusters/automate/dev-lxc.yml

We can easily append additional configurations to this file. For example, the following command appends an infrastructure node.

dl init --nodes -a -f /root/work/clusters/automate/dev-lxc.yml

Edit the dev-lxc.yml file:

  • Delete the reporting product from the Chef Server config since we will be using Chef Automate's Visibility.
  • Set the Automate server's license_path value to the location of your license file.
  • (Optionally) If you built other clusters then you can modify the server names (including the nodes' chef_server_url) in this cluster to make them unique from the other clusters.

cluster-view

Run the cluster-view command to create a Byobu session specifically for this cluster.

The session's first window is named "cluster".

The left pane is useful for running dev-lxc commands.

The right pane updates every 0.5 seconds with the cluster's status provided by dev-lxc status.

The session's second window is named "shell". It opens in the same directory as the cluster's dev-lxc.yml file and is useful for attaching to a server to perform system administration tasks.

See the usage docs for more information about how to close/kill Byobu sessions.

cluster-view /root/work/clusters/automate

Specifying a Subset of Servers

Many dev-lxc subcommands can act on a subset of the cluster's servers by specifying a regular expression that matches the desired server names.

For example, the following command will show the status of the build node and the infrastructure node.

dl status node

Build the Cluster

dev-lxc knows to build the servers in an appropriate order.

It downloads the product packages to a cache location and installs the packages in each server.

It configures each product and creates necessary things such as Chef organizations and users as needed.

dl up

Note: You also have the option of running the prepare-product-cache subcommand which downloads required product packages to the cache.
This can be helpful when you don't want to start building the cluster yet but you want the package cache ready when you build the cluster later.

Use the Servers

At this point all of the cluster's servers should be running.

If you setup the workstation's networking correctly as described in the prerequisites you should be able to ping any server from your workstation using it's FQDN. You can also browse to any server that has a web interface.

Since the cluster has a Chef Server you can use the chef-repo subcommand to create a chef-repo directory in the VM that contains a knife.rb and all of the keys for the users and org validator clients that are defined in dev-lxc.yml. This makes it very easy to use tools such as knife or berkshelf.

dl chef
cd chef-repo
knife client list
cd ..

Since the cluster has a Chef Automate server you can use the print-automate-credentials subcommand to see what the login credentials.

dl print

You can use the attach subcommand to login to the root user of a server.

For example, the following command should attach to the Chef Server.

dl at chef

Since the cluster has a Chef Server and an infrastructure node dev-lxc made sure it configured the node's chef-client for the Chef Server so it is easy to converge the node.

Manage the Cluster

The right pane of the "cluster" window should show dev-lxc status output. This shows the status of each server including any existing snapshots.

It is recommended that you stop the servers before restoring or creating snapshots.

dl halt

You can restore the most recent snapshot of all the servers.

dl sn -r

You could also restore a specific snapshot by name if you desire.

For example, you could restore the Chef Automate server to the state right after its package was installed but before it was configured.

dl sn automate -r snap0

You can create snapshots with or without a comment.

dl sn -c 'Demo snapshot'

You can destroy snapshots.

dl sn -d snap2

And finally you can destroy the servers and there snapshots.

dl d

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request