dev-lxc

A tool for creating Chef Server clusters and Chef Analytics clusters using LXC containers.

Using ruby-lxc it builds a standalone Chef Server or tier Chef Server cluster composed of a backend and multiple frontends with round-robin DNS resolution. It can also build a standalone or tier Chef Analytics server and connect it with the Chef Server.

dev-lxc also has commands to manipulate Chef node containers. For example, dev-lxc can bootstrap a container by installing Chef Client, configuring it for a Chef Server and running a specified run_list.

The dev-lxc tool is well suited as a tool for support related work, customized cluster builds for demo purposes, as well as general experimentation and exploration of Chef products

Features

1. LXC 1.0 Containers - Resource efficient servers with fast start/stop times and standard init
2. Btrfs - Efficient, persistent storage backend provides fast, lightweight container cloning
3. Dnsmasq - DHCP networking and DNS resolution
4. Platform Images - Images that are built to resemble a traditional server
5. ruby-lxc - Ruby bindings for liblxc
6. YAML - Simple, customizable definition of clusters; No more setting ENV variables
7. Build process closely follows online installation documentation
8. Images - Images are created during the cluster's build process which makes rebuilding a cluster very fast.

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 clones 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

• dev-lxc-platform

  The dev-lxc tool is designed to be used in a platform built by dev-lxc-platform.

  Please follow the dev-lxc-platform usage instructions to create a suitable platform.

  The dev-lxc-platform will automatically install this dev-lxc tool.

• Use root user

  Once you login to the Vagrant VM platform you should run sudo -i to login as the root user.

  Consider using byobu or tmux for a terminal multiplexer as dev-lxc-platform README describes.

• Setup Mounts and Packages

  As described below dev-lxc uses a dev-lxc.yml config file for each cluster. Be sure that you configure the mounts and packages lists in dev-lxc.yml to match your particular environment.

  The package paths in dev-lxc's example configs assume that the packages are stored in the following directory structure in the dev-lxc-platform VM. I recommend creating that directory structure in the physical workstation and configuring dev-lxc-platform's .knife.yml to mount the structure into /root/dev in the dev-lxc-platform VM.

/root/dev/chef-packages/
├── analytics
├── cs
├── ec
├── manage
├── osc
├── push-jobs-server
└── reporting

Update dev-lxc gem

Run gem update dev-lxc inside the Vagrant VM platform to ensure you have the latest version.

Usage

Display Help

dev-lxc help

dev-lxc -h

dev-lxc --help

dev-lxc help <subcommand>

Shorter Commands are Faster (to type that is :)

The dev-lxc-platform's root user's ~/.bashrc file has aliased dl to dev-lxc for ease of use but for most instructions in this README I will use dev-lxc for clarity.

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

The following commands are equivalent:

dev-lxc init --chef > dev-lxc.yml
dl i --chef > dev-lxc.yml

dev-lxc up
dl u

dev-lxc status
dl st

dev-lxc destroy
dl d

Create and Manage a Cluster

The following instructions will build a tier Chef Server with an Analytics server for demonstration purposes. The size of this cluster uses about 3GB ram and takes awhile for the first build of the servers. Feel free to try the standalone config first.

Define cluster

The following command saves a predefined config to dev-lxc.yml.

Be sure you configure the mounts and packages entries appropriately.

dev-lxc init --tiered-chef --analytics > dev-lxc.yml

List Images

List of each servers' images created during the build process.

dev-lxc list-images

Cluster status

Run the following command to see the status of the cluster.

dev-lxc status

This is an example of the output.

Chef Server: https://chef.lxc

Analytics:   https://analytics.lxc

      chef-be.lxc     running         10.0.3.203
     chef-fe1.lxc     running         10.0.3.204
 analytics-be.lxc     running         10.0.3.206
analytics-fe1.lxc     running         10.0.3.207

cluster-view, tks, tls commands

The dev-lxc-platform comes with some commands that create and manage helpful tmux/byobu sessions to more easily see the state of a cluster.

Running the cluster-view command in the same directory as a dev-lxc.yml file creates a tmux/byobu session with the same name as the cluster's directory. cluster-view can also be run with the parent directory of a dev-lxc.yml file as the first argument and cluster-view will change to that directory before creating the tmux/byobu session.

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

The left side is for running dev-lxc commands.

The right side is made up of three vertically stacked panes with each pane's content updating every 0.5 seconds.

• Top - system's memory usage provided by free -h
• Middle - cluster's status provided by dev-lxc status
• Bottom - list of the cluster's images provided by dev-lxc list-images

The session's second window is named "shell". It opens in the same directory as the cluster's dev-lxc.yml file.

The tls and tks commands are really aliases.

tls is an alias for tmux list-sessions and is used to see what tmux/byobu sessions are running.

tks is an alias for tmux kill-session -t and is used to kill tmux/byobu sessions. When specifying the session to be killed you only need as many characters of the session name that are required to make the name unique among the list of running sessions.

I recommend switching to a different running tmux/byobu session before killing the current tmux/byobu session. Otherwise you will need to reattach to the remaining tmux/byobu session. Use the keyboard shortcuts Alt-Up/Down to easily switch between tmux/byobu sessions.

Start cluster

Starting the cluster the first time takes awhile since it has a lot to build.

The tool automatically creates images at appropriate times so future creation of the cluster's servers is very quick.

dev-lxc up

A test org, user, knife.rb and keys are automatically created in the bootstrap backend server in /root/chef-repo/.chef for testing purposes.

The knife-opc plugin is installed in the embedded ruby environment of the Private Chef and Enterprise Chef server to facilitate the creation of the test org and user.

Create chef-repo

Create a local chef-repo with appropriate knife.rb and pem files.

Use the -p option to also get pivotal.pem and pivotal.rb files.

Use the -f option to overwrite existing knife.rb and pivotal.rb files.

dev-lxc chef-repo

Now you can easily use knife to access the cluster.

cd chef-repo
knife ssl fetch
knife client list

Cheap cluster rebuilds

Clones of the servers as they existed immediately after initial installation, configuration and test org and user creation are available so you can destroy the cluster and "rebuild" it within seconds effectively starting with a clean slate very easily.

dev-lxc destroy
dev-lxc up

Stop and start the cluster

dev-lxc halt
dev-lxc up

Backdoor access to each server's filesystem

The realpath subcommand can be used to prepend each server's rootfs path to a particular file.

For example, you can use the following command to edit the Chef Servers' chef-server.rb file without logging into the containers.

emacs $(dev-lxc realpath chef /etc/opscode/chef-server.rb)

Run arbitrary commands in each server

After modifying the chef-server.rb you could use the run-command subcommand to tell the backend and frontend servers to run chef-server-ctl reconfigure.

dev-lxc run-command chef 'chef-server-ctl reconfigure'

Attach the terminal to a server

Attach the terminal to a server in the cluster that matches the REGEX pattern given.

dev-lxc attach chef-be

Make a snapshot of the servers

Save the changes in the servers to custom images.

dev-lxc halt
dev-lxc snapshot

Now the servers can be destroyed and recreated with the same changes captured at the time of the snapshot.

dev-lxc destroy
dev-lxc up

Destroy cluster

Use the following command to destroy the cluster's servers and also destroy their custom, unique and shared images if you want to build them from scratch.

dev-lxc destroy -c -u -s

Global status of all dev-lxc images and servers

Use the global-status command to see the status of all dev-lxc images and servers stored in dev-lxc's default LXC config_path /var/lib/dev-lxc.

dev-lxc global-status

Use commands against specific servers

You can also run most of these commands against a set of servers by specifying a regular expression that matches a set of server names.

dev-lxc <subcommand> [SERVER_NAME_REGEX]

For example, to only start the Chef Servers named chef-be.lxc and chef-fe1.lxc you can run the following command.

dev-lxc up chef

Adhoc Clusters

dev-lxc can also manage an adhoc cluster of servers.

An adhoc cluster is just a set of managed servers cloned from the specified platform image. The servers have SSH server running, a "dev-lxc" user with "dev-lxc" password and passwordless sudo access.

This is particularly useful when you want to use something else, such as chef-provisioning, to configure the servers.

The number of servers, their names and their IP addresses can be changed to fit your particular requirements.

The "adhoc" template provides an example cluster configuration suitable for creating a Chef Delivery cluster.

mkdir -p /root/dev/clusters/delivery
cd /root/dev/clusters/delivery
dev-lxc init --adhoc > dev-lxc.yml
cluster-view
dl up

Managing Node Containers

Manually Create a Platform Image

Platform images can be used for purposes other than building clusters. For example, they can be used as Chef nodes for testing purposes.

Platform images have openssh-server installed and running with unique SSH Host Keys.

Platform images have a "dev-lxc" user with "dev-lxc" password and passwordless sudo.

You can see a menu of platform images this tool can create by using the following command.

dev-lxc create

The initial creation of platform images can take awhile so let's go ahead and start creating an Ubuntu 14.04 image now.

dev-lxc create p-ubuntu-1404

Note: It is possible to pass additional arguments to the underlying LXC create command. For example:

dev-lxc create p-ubuntu-1404 -o -- '--no-validate --keyserver http://my.key.server.com'

Install Chef Client in a Container

Use the -v option to specify a particular version of Chef Client.

Use -v latest or leave out the -v option to install the latest version of Chef Client.

For example, install the latest 11.x version of Chef Client.

dev-lxc install-chef-client test-node.lxc -v 11

Configure Chef Client in a Container

Use the -s, -u, -k options to set chef_server_url, validation_client_name and validation_key in a container's /etc/chef/client.rb and copy the validator's key to /etc/chef/validation.pem.

Or leave the options empty and it will default to using values from the cluster defined in dev-lxc.yml.

dev-lxc config-chef-client test-node.lxc

Bootstrap Chef Client in a Container

Specifying a BASE_CONTAINER_NAME will clone the base container into a new container and bootstrap it. If no BASE_CONTAINER_NAME is given then the container to be bootstrapped needs to already exist.

Use the -v option to specify a particular version of Chef Client.

Use the -s, -u, -k options to set chef_server_url, validation_client_name and validation_key in a container's /etc/chef/client.rb and copy the validator's key to /etc/chef/validation.pem.

Or leave the options empty and it will default to using values from the cluster defined in dev-lxc.yml.

Use the -r option to specify the run_list for chef-client to use.

dev-lxc bootstrap-container test-node.lxc -r my_run_list

Using the dev-lxc library

dev-lxc cli interface can be used as a library.

require 'dev-lxc/cli'

ARGV = [ 'up' ]         # start all servers
DevLXC::CLI::DevLXC.start

ARGV = [ 'status' ]        # show status of all servers
DevLXC::CLI::DevLXC.start

ARGV = [ 'run-command', 'uptime' ]   # run `uptime` in all servers
DevLXC::CLI::DevLXC.start

ARGV = [ 'destroy' ]       # destroy all servers
DevLXC::CLI::DevLXC.start

dev-lxc itself can also be used as a library

require 'yaml'
require 'dev-lxc'

config = YAML.load(IO.read('dev-lxc.yml'))
server = DevLXC::Server.new("chef-fe1.lxc", 'chef-server', config)

server.start               # start chef-fe1.lxc
server.status              # show status of chef-fe1.lxc
server.run_command("chef-server-ctl reconfigure")  # run command in chef-fe1.lxc
server.stop                # stop chef-fe1.lxc
server.destroy             # destroy chef-fe1.lxc

Cluster Config Files

dev-lxc uses a YAML configuration file named dev-lxc.yml to define a cluster.

The following command generates sample config files for various cluster topologies.

dev-lxc init

dev-lxc init --tiered-chef --analytics > dev-lxc.yml creates a dev-lxc.yml file with the following content:

## platform_image can be one of the following:
## p-centos-5, p-centos-6, p-centos-7, p-ubuntu-1204, p-ubuntu-1404 or p-ubuntu-1504

## platform_image_options can be set to provide additional arguments to the LXC create command.
## reference arg examples: https://github.com/lxc/lxc/blob/lxc-2.0.0/templates/lxc-download.in#L200-L207
## for example:
## platform_image_options: --no-validate --keyserver http://my.key.server.com

## Make sure all mount source directories exist in the LXC host

## Make sure all package paths are correct

## All FQDNs and server names must end with the `.lxc` domain

## DHCP reserved (static) IPs must be selected from the IP range 10.0.3.150 - 254

## topology can be one of the following:
## standalone (default), tier or open-source (for the old open source 11 chef server)

platform_image: p-ubuntu-1404
mounts:
  - /root/dev root/dev

chef-server:
  packages:
    server: /root/dev/chef-packages/cs/chef-server-core_12.5.0-1_amd64.deb
    manage: /root/dev/chef-packages/manage/chef-manage_2.2.1-1_amd64.deb
    reporting: /root/dev/chef-packages/reporting/opscode-reporting_1.5.6-1_amd64.deb
    push-jobs-server: /root/dev/chef-packages/push-jobs-server/opscode-push-jobs-server_1.1.6-1_amd64.deb
  topology: tier
  api_fqdn: chef.lxc
  servers:
    chef-be.lxc:
      ipaddress: 10.0.3.201
      role: backend
      bootstrap: true
    chef-fe1.lxc:
      ipaddress: 10.0.3.202
      role: frontend

analytics:
  packages:
    analytics: /root/dev/chef-packages/analytics/opscode-analytics_1.3.1-1_amd64.deb
  servers:
    analytics.lxc:
      ipaddress: 10.0.3.204

This config defines a tier cluster consisting of a single backend and a single frontend.

A second frontend is commented out to conserve resources. If you uncomment the second frontend then both frontends will be created and dnsmasq will resolve the api_fqdn chef.lxc to both frontends using a round-robin policy.

The config file is very customizable. You can add or remove mounts, packages or servers, change ip addresses, change server names, change the platform_image and more.

The mounts list describes what directories get mounted from the Vagrant VM platform into each container. You need to make sure that you configure the mount entries to be appropriate for your environment.

The same is true for the packages list. The paths that are provided in the default configs are just examples. You need to make sure that you have each package you want to use downloaded to appropriate directories that will be available to the container when it is started.

I recommend downloading the packages to a directory on your workstation. Then configure the dev-lxc-platform's .kitchen.yml to mount that directory in the Vagrant VM platform. Then configure the cluster's mount entries in dev-lxc.yml to mount the Vagrant VM platform's directory into each container.

Make sure the mounts and packages represent actual paths that are available in your environment.

Managing Multiple Clusters

By default, dev-lxc looks for a dev-lxc.yml file in the present working directory. You can also specify a particular config file as an option for most dev-lxc commands.

The following is an example of managing multiple clusters while still avoiding specifying each cluster's config file.

mkdir -p ~/clusters/{clusterA,clusterB}
dev-lxc init --tiered-chef > ~/clusters/clusterA/dev-lxc.yml
dev-lxc init --chef > ~/clusters/clusterB/dev-lxc.yml
cd ~/clusters/clusterA && dev-lxc up  # starts clusterA
cd ~/clusters/clusterB && dev-lxc up  # starts clusterB

Maintain Uniqueness Across Multiple Clusters

The default cluster configs are already designed to be unique from each other but as you build more clusters you have to maintain uniqueness across the YAML config files for the following items.

• Server names, api_fqdn and analytics_fqdn

  Server names should really be unique across all clusters.

  Even when cluster A is shutdown, if cluster B uses the same server names when it is created it will use the already existing servers from cluster A.

  api_fqdn and analytics_fqdn uniqueness only matters when clusters with the same api_fqdn and analytics_fqdn are running.

  If cluster B is started with the same api_fqdn or analytics_fqdn as an already running cluster A, then cluster B will overwrite cluster A's DNS resolution of api_fqdn or analytics_fqdn.

  It is easy to provide uniqueness in the server names, api_fqdn and analytics_fqdn. For example, you can use the following command to prefix the servers names with 1234- when generating a cluster's config.

  dev-lxc init --tiered-chef 1234- > dev-lxc.yml
  

• IP Addresses

  IP addresses uniqueness only matters when clusters with the same IP's are running.

  If cluster B is started with the same IP's as an already running cluster A, then cluster B will overwrite cluster A's DHCP reservation of the IP's but dnsmasq will still refuse to assign the IP's to cluster B because they already in use by cluster A. dnsmasq then assigns random IP's from the DHCP pool to cluster B leaving it in an unexpected state.

  The dev-lxc-platform creates the IP range 10.0.3.150 - 254 for DHCP reserved IP's.

  Use unique IP's from that range when configuring clusters.

Images

One of the key things this tool uses is the concept of images.

dev-lxc creates images with a "p-", "s-", "u-" or "c-" prefix on the name to distinguish it as a "platform", "shared", "unique" or "custom" image.

Images are then cloned using the btrfs filesystem to very quickly provide a lightweight duplicate of the image. This clone is either used to build the next image in the build process or the final container that will actually be run.

By default, the cluster's images and final server containers are all stored in /var/lib/dev-lxc so they don't clutter the containers stored in the default LXC config_path /var/lib/lxc.

The cluster's LXC config_path can be configured by setting lxc_config_path at the top of the dev-lxc.yml file to the desired directory.

There are four image categories.

1. Platform Image

   The platform image is the first to get created and is identified by the "p-" prefix on the image name.

   DevLXC#create_platform_image controls the creation of a platform image.

   This image provides the chosen OS platform and version (e.g. p-ubuntu-1404). A typical LXC container has minimal packages installed so dev-lxc makes sure that the same packages used in Chef's bento boxes are installed to provide a more typical server environment. A few additional packages are also installed.

   Platform images have openssh-server installed and running with unique SSH Host Keys.

   Platform images have a "dev-lxc" user with "dev-lxc" password and passwordless sudo.

   Once this platform image is created there is rarely a need to delete it.

2. Shared Image

   The shared image is the second to get created and is identified by the "s-" prefix on the image name.

   DevLXC::Server#create_shared_image controls the creation of a shared image.

   Chef packages that are common to all servers in a Chef cluster, such as chef-server-core, opscode-reporting and opscode-push-jobs-server are installed using dpkg or rpm.

   Note the manage package will not be installed at this point since it is not common to all servers (i.e. it does not get installed on backend servers).

   The name of this image is built from the names and versions of the Chef packages that get installed which makes this image easy to be reused by another cluster that is configured to use the same Chef packages.

   Since no configuration actually happens yet there is rarely a need to delete this image.

3. Unique Image

   The unique image is the last to get created and is identified by the "u-" prefix on the image name.

   DevLXC::Server#create controls the creation of a unique image.

   Each unique Chef server (e.g. standalone, backend or frontend) is created.

* The specified hostname is assigned.
* dnsmasq is configured to reserve the specified IP address for the image's MAC address.
* A DNS entry is created in dnsmasq if appropriate.
* All installed Chef packages are configured.
* Test users and orgs are created.
* The opscode-manage package is installed and configured if specified.

After each server is fully configured a clone of it is made resulting in the server's
unique image. These unique images make it very easy to quickly recreate
a Chef cluster from a clean starting point.

1. Custom Image

   The custom image is only created when the snapshot command is used and is identified by the "c-" prefix on the image name.

   DevLXC::Server#snapshot controls the creation of a custom image.

   Custom images can be used to save the changes that have been made in servers. Later, when the servers are destroyed and recreated, they will start running with the changes that were captured at the time of the snapshot.

Destroying Images

When using dev-lxc destroy to destroy servers you have the option to also destroy any or all of the four types of images associated with the servers.

The following command will list the options available.

dev-lxc help destroy

Of course, you can also just use the standard LXC commands to destroy any container.

lxc-destroy -n [NAME]

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