LittleChef

With LittleChef you will be able to get started more quickly cooking with Chef, the excellent Configuration Management System.

Overview

You may think of this like a pocket Chef that doesn't need a Chef Server. Just your local kitchen with all your cookbooks, roles data bags and nodes, which will get rsynced to a node each time you start a Chef Solo configuration run with the bundled fix command.

It also adds features to Chef Solo that are currently only available for Chef Server users: data bag search, and node search.

How it all works

It all starts in the kitchen, which you should keep under version control:

• auth.cfg: Authentication information needed to be able to connect to the nodes
• nodes/: After recipes are run on Nodes, their configuration is stored here in JSON format. You can manually edit them or even add new ones. The name of a node should be its FQDN
• cookbooks/: This will be your Cookbooks repository
• site-cookbooks/: Here you can override upstream cookbooks (Opscode's, for example)
• roles/: Where Chef Roles are defined in JSON
• data_bags/: Chef Data Bags. JSON databag items. Search is supported
• plugins/: Your plugin tasks

Whenever you start a Chef Solo configuration run with the local fix command, all cookbooks, roles and databags are rsynced to the /tmp/chef-solo/ directory, together with the /etc/chef/node.json and /etc/chef/solo.rb files, and chef-solo is executed at the remote node.

The result is that you can configure your nodes exactly when and how you want, all without needing a Chef Server. And all your infrastructure, including your nodes, will be in code, revision controlled.

Data bag Search

Chef Solo does not currently (as of 0.10.4) support data bag search. LittleChef adds search support by automatically adding to your node cookbooks a cookbook library that implements search.

Thus, most examples in the search wiki page are now possible, including the following example: search(:users, "married:true AND age:35")

Environments

Chef Solo does not support Environments but, similarly to the search case, LittleChef will automatically add a cookbook library that will let you define chef_environment in a role or node.

Node Search

Node search is achieved by creating a "node" data bag on the fly for every run, with the data from each node defined in nodes/, but with the attribute values being the result from merging cookbook, node and role attributes, following the standard Chef attribute preference rules. Some automatic attributes are also added.

munin_servers = search(:node, "role:#{node['munin']['server_role']} AND chef_environment:node.chef_environment']}")`

Logs

Chef Solo output for a configuration run will be found at the node's /var/log/chef/solo.log, and the previous configuration run will be moved to solo.log.1.

metadata.rb and ruby roles

LittleChef depends on the JSON versions of the cookbook metadata and roles to properly merge attributes. You can still use the ruby versions, and generate the JSON versions when you make changes. If you have knife locally installed, it will even be done automatically on every run if a changed metadata.rb is detected. Ruby roles are not yet automatically converted, but an implementation is planned.

Plugins

You can define your own LittleChef tasks as Python plugin modules. They should be located in the plugins directory. The filename will be the plugin name and the module docstring the description. Each plugin should define an execute funtion, which will then be executed when applying a plugin on a node (the Cooking section describes how to run a plugins).

You can find example plugins in the repository plugins directory

Installation

Desktop support

Tested on all three major desktops:
Linux, Mac OS X, and Windows

Requirements

• Python 2.6+
• Fabric 1.0.1+

The best way to install LittleChef is using pip. Required packages are installed by typing:
sudo apt-get install python-pip python-dev for Debian and Ubuntu
or
yum install python-pip python-devel for RHEL and CentOS

pip will then take care of the extra Python dependencies

Installation

You can install LittleChef directly from the PyPI:
pip install littlechef

Usage

Disclaimer

Careful what you do with your nodes!:

A certain famous Chef: What do I always say? Anyone can cook.
LittleChef: Yeah. Anyone can, that doesn't mean that anyone should.

Local Setup

fix new_kitchen will create inside the current directory a few files and directories for LittleChef to be able to cook: auth.cfg, roles/, data_bags/, nodes/, cookbooks/ and site-cookbooks/. You can create and have as many kitchens as you like on your computer.

Authentication

To be able to issue commands to remote nodes, you need to enter a user and a password with sudo rights. new_kitchen will have created a file named auth.cfg. You can edit it now to enter needed authentication data. There are several possibilities:

• username and password
• username, password and keypair-file
• A reference to an ssh-config file

The last one allows the most flexibility, as it allows you to define different usernames, passwords and/or keypair-files per hostname. LittleChef will look at ~/.ssh/config by default, but you can always specify another path in auth.cfg:

[userinfo]
user = myusername
password = mypassword
ssh-config = /path/to/config/file

An example ~/.ssh/config file:

Host www.cooldomain.com
    HostName www.cooldomain.com
    IdentityFile ~/.ssh/prod_rsa
    User produser
Host *.devdomain.com
    IdentityFile ~/.ssh/dev_rsa
    User devuser

Deploying

For convenience, there is a command that allows you to deploy chef-solo to a node.

The best way is to use the packages from the Opscode repository:
fix node:MYNODE deploy_chef

LittleChef will try to autodetect the distro type and version of that node, and will use the appropriate installation method and packages.

You can also install Chef Solo with gems and/or without asking for confirmation:
fix node:MYNODE deploy_chef:gems=yes,ask=no

Currently supported Linux distributions include Ubuntu, Debian, CentOS, RHEL, Scientific Linux, Gentoo, and Arch Linux.

When using the Debian repository, you need to take into account that Opscode has separated Chef versions in different repos. Current default is Chef 0.10, but you can install Chef 0.9 by typing: fix node:MYNODE deploy_chef:version=0.9

Also, if you still want to keep the chef-client around in debian, use the stop_client option: fix node:MYNODE deploy_chef:stop_client=no

Note that if you already have Chef Solo installed on your nodes, you won't need this. Also, if you previously installed Chef using the Gem procedure, please don't use the deploy_chef package installation method, removing the gem first might be a good idea.

Cooking

Note: Don't cook outside of a kitchen!

List of commands:

• fix -v: Shows the version number
• fix -l: Show a list of all available orders
• fix node:MYNODE recipe:MYRECIPE: Cook a recipe on a particular node by giving its hostname or IP. "Subrecipes" like nginx::source are supported. Note that the first time this is run for a node, a configuration file will be created at nodes/myhostname.json. You can then edit this file to override recipe attributes, for example. Further runs of this command will not overwrite this configuration file
• fix node:MYNODE role:MYROLE: The same as above but role-based
• fix node:MYNODE1,MYNODE2: Configures several pre-configured nodes, in order
• fix node:all: It will apply all roles, recipes and attributes defined for each and every node in nodes/
• fix --env=MYENV node:all: Configures all nodes which have the attribute chef_environment set to MYENV
• fix nodes_with_role:ROLE1: Configures all nodes which have a certain role in their run_list
• fix nodes_with_role:ROL*: Configures all nodes which have at least one role which starts with 'ROL' in their run_list
• fix node:MYNODES ssh:"my shell command": Executes the given command on the node
• fix node:MYNODES plugin:save_ip: Gets the actual IP for this node and saves it in the ipaddress attribute

Options:

• fix --env=MYENV nodes_with_role:ROLE1: Configures all nodes in the environment MYENV which have a certain role in their run_list.
• fix --verbose node:MYNODE: Chef 0.10.6 introduced the verbose_logging option. When false, the "processing" messages are not longer shown. That is the new default for LittleChef, so that you now only see what has changed in this configuration run. --verbose switches this back on.
• fix --debug node:MYNODE: You can start all your commands with fix --debug to see all Chef Solo debugging information. Also, the node file and node databag wont't be deleted from the node, and verbose will also be true
• fix --no-report node:MYNODE: will prevent the logging of Chef Solo output to /var/log/chef/

Once a node has a config file, the command you will be using most often is fix node:MYNODE, which allows you to repeatedly tweak the recipes and attributes for a node and rerun the configuration.

Consulting the inventory

• fix list_nodes: Lists all configured nodes, showing its associated recipes and roles
• fix list_nodes_detailed: Same as above, but it also shows all attributes
• fix list_nodes_with_recipe:MYRECIPE: Lists nodes which have associated the recipe MYRECIPE
• fix list_nodes_with_role:MYROLE: Shows nodes which have associated the role MYROLE
• fix list_recipes: Lists all available recipes
• fix list_recipes_detailed: Same as above, but shows description, version, dependencies and attributes
• fix list_roles: Lists all available roles
• fix list_roles_detailed: Same as above, but shows description and attributes
• fix list_plugins: Show a list of available plugins

Using LittleChef as a library

You can import littlechef.py into your own Python project. The following script is equivalent to using the fix orders:

from littlechef import runner as lc
lc.env.user = 'MyUsername'
lc.env.password = 'MyPassword'
lc.env.host_string = 'MyHostnameOrIP'
lc.deploy_chef(gems='yes', ask='no')

lc.recipe('MYRECIPE') #Applies <MYRECIPE> to <MyHostnameOrIP>
lc.node('MyHostnameOrIP') #Applies the saved nodes/MyHostnameOrIP.json configuration

Other tutorial material

• Automated Deployments with LittleChef, nice introduction to Chef using LittleChef

Getting help

For help regarding the use of LittleChef, or to share any ideas or suggestions you may have, please post on LittleChef's discussion group

Reporting bugs

If you find bugs please report it on https://github.com/tobami/littlechef/issues

Happy cooking!