Kafo

A puppet based installer and configurer (not-only) for Foreman and Katello projects. Kafo is a ruby gem that allows you to create fancy user interfaces for puppet modules. It's some kind of a nice frontend to a

echo "include some_modules" | puppet apply

Why should I care?

Suppose you work on software which you want to distribute to a machine in infrastructure managed by puppet. You write a puppet module for your app. But you also want to be able to distribute this app to a machine outside of puppet infrastructure (e.g. install it to your clients) or you want to install it in order to create a puppet infrastructure itself (e.g. foreman or foreman-proxy).

With kafo you can reuse your puppet modules for creating an installer. Even better after the installation you can easily modify you configuration. All using the very same puppet modules.

What it does, how does it work?

Kafo reads a config file to find out which modules should it use. Then it loads parameters from puppet manifests and gives you a way to customize them.

There are three ways how you can set parameters. You can

• predefine them in configuration file
• specify them as CLI arguments
• you can use interactive mode which will ask you for all required parameters

Note that your answers (gathered from any mode) are saved for the next run so you don't have to specify them again. Kafo also support default values of parameters so you can set only those you want to change. Also you can combine akk modes so you can create an answer file with default values easily and then use it for unattended installs.

How do I use it?

First install kafo gem.

Using bundler - add kafo gem to your Gemfile and run

bundle install

or without bundler

gem install kafo

Create a directory for your installer. Let's say we want to create foreman-installer.

mkdir foreman-installer
cd foreman-installer

Now we run kafofy script which will prepare directory structure and optionally create a bin script according to first parameter.

kafofy -n foreman-installer

You can see that it created modules directory where your puppet modules should live. It also created config and bin directories. If you specify argument --name (or -n for short, foreman-installer in this case) a script in bin is created.

It's the script you can use to run installer. If you did not specify any you can run your installer by kafo-configure which is the default. All configuration related files are to be found in config directory.

You can supply custom locations for you configuration and answers files using options:

Usage: kafofy [options]
    -a, --answer_file FILE           location of the answer file
    -c, --config_file FILE           location of the configuration file
    -n, --name        NAME           your installer name

Configuration file will be created by default template. It's the configuration of you installer (so you can setup log level, path to puppet modules etc). On the other hand, answer file must be created manually. Answer file defines which modules should be used and hold all values for puppet class parameters.

So for example to install foreman you want to

cd foreman-installer/modules
git clone https://github.com/theforeman/puppet-foreman/ foreman

You must also download any dependant modules. Then you need to tell kafo it's going to use foreman module.

cd ..
echo "foreman: true" > config/answers.yaml

Alternatively you can use librarian-puppet project to manage all deps for you. You just create a Puppetfile and call librarian to install your modules. See https://github.com/rodjek/librarian-puppet for more details.

When you have your modules in-place, fire the installer with -h argument

bin/foreman-installer -h

You will see all arguments that you can pass to kafo. Note that underscored puppet parameters are automatically converted to dashed arguments. You can also see a documentation extracted from foreman puppet module and default value.

Now run it without -h argument. It will print you the puppet apply command to execute. This will be automatized later. Look at config/answers.yaml, it was populated with default values. To change those options you can use arguments like this

bin/foreman-installer --foreman-enc=false --foreman-db-type=sqlite

or you can run interactive mode

bin/foreman-installer --interactive

Also every change made to config/answers.yaml persists and becomes new default value for next run.

As you noticed there are several ways how to specify arguments. Here's the list the lower the item is the higher precedence it has:

• default values from puppet modules
• values from answers.yaml
• values specified on CLI
• interactive mode arguments

Advanced topics

Testing aka noop etc

You'll probably want to tweak your installer before so you may find --noop argument handy (-n for short). This will run puppet in noop so no change will be done to your system. Default value is false!

Sometimes you may want kafo not to store answers from current run. You can disable saving by passing a --dont-save-answers argument (or -d for short).

Parameters prefixes

You probably noticed that every module parameter is prefixed by module name by default. If you use just one module it's probably unnecessary and you can disable this behavior in config/kafo.yaml. Just set option like this

:no_prefix: true

Documentation

Every parameter that can be set by kafo must be documented. This means that you must add documentation to your puppet class in init.pp. It's basically rdoc formatted documentation that must be above class definitions. There can be no space between doc block and class definition.

In case of emergency, it's still possible to use --ignore-undocumented option, but in general it's not recommended to use it long-term.

Example:

# Manage your foreman server
#
# This class ...
# ... does what it does.
#
# === Parameters:
#
# $foreman_url::            URL on which foreman is going to run
#
# $enc::                    Should foreman act as an external node classifier (manage puppet class
#                           assignments)
#                           type:boolean
class foreman (
  $foreman_url            = $foreman::params::foreman_url,
  $enc                    = $foreman::params::enc
) {
  class { 'foreman::install': }
}

You can separate your parameters into groups like this.

Example - separating parameters into groups:

# Manage your foreman server
#
# === Parameters:
#
# $foreman_url::            URL on which foreman is going to run
#
# === Advanced parameters:
#
# $foreman_port::           Foreman listens on this port
#
# ==== MySQL:
#
# $mysql_host::             MySQL server address

When you run the installer with --help argument it displays only parameters specified in === Parameters: group. If you don't specify any group all parameters will be considered as Basic and will be displayed.

If you run installer with --full-help you'll receive help of all parameters divided into groups. Note that only headers that include word parameters are considered as parameter groups. Other headers are ignored. Also note that you can nest parameter groups and the child has precedence. Help output does not take header level into account though.

So in previous example, each parameter would be printed in one group even though MySQL is a child of Advanced parameter. All groups in help would be prefixed with second level (==). The first level is always a module to which particular parameter belongs.

Argument types

By default all arguments that are parsed from puppet are treated as string. If you want to indicate that a parameter has a particular type you can do it in puppet manifest documentation like this

# $param::        Some documentation for param
                  type:boolean

Supported types are: string, boolean, integer, array, password

Note that all arguments that are nil (have no value in answers.yaml or you set them UNDEF (see below) are translated to undef in puppet.

Password arguments

Kafo support password arguments. It's adding some level of protection for you passwords. Usually people generate random strings for passwords. However all values are stored in config/answers.yaml which introduce some security risk.

If this is something to consider for you, you can use password type (see Argument types for more info how to define parameter type). It will generate a secure (random) password of decent length (32 chars) and encrypts it using AES 256 in CBC mode. It uses a passphrase that is stored in config/kafo.yaml so if anyone gets an access to this file, he can read all other passwords from answers.yaml. A random password is generated and stored if there is none in kafo.yaml yet.

When Kafo runs puppet, puppet will read this password from config/kafo.yaml. It runs under the same user so it should have read access by default. Kafo puppet module also provides a function that you can use to decrypt such parameters. You can use it like this

password: <%= scope.function_decrypt([scope.lookupvar("::foreman::db_password"))]) -%>

Also you can take advantage of already encrypted password and store as it is (encrypted). Your application can decrypt it as long as it knows the passphrase. Passphrase can be obtained as $kafo_configure::password.

Note that we use a bit extraordinary form of encrypted passwords. All our encrypted passwords looks like "$1$base64encodeddata". As you can see we use $1$ prefix by which we can detect that its encrypted password by us. The form has nothing common with Modular Crypt Format. Also our AES output is base64 encoded. To get a password from this format you can do something like this in your application

require 'base64'
encrypted = "$1$base64encodeddata"
encrypted = encrypted[3..-1]           # strip $1$ prefix
encrypted = Base64.decode64(encrypted) # decode base64 string
result    = aes_decrypt(encrypted)     # for example how to implement aes_decrypt see lib/kafo/password_manager.rb

Array arguments

Some arguments may be Arrays. If you want to specify array values you can specify CLI argument multiple times e.g.

bin/foreman-installer --puppetmaster-environments=development --puppetmaster-environments=production

In interactive mode you'll be prompted for another value until you specify blank line.

Hash arguments

You can use Hash value not unlike Arrays. It's also multivalue type but you have to specify a key:value pairs like this.

bin/foreman-installer --puppet-server-git-branch-map=master:some --puppet-server-git-branch-map=development:another

The same applies in interactive mode, you enter each pair on separate line just like with Array, the only difference is that the line must be formatted as key:value.

When parsing the value, the first colon divides key and value. All other colons are ignored.

Grouping in interactive mode

If your module has too much parameters you may find useful grouping. Every block in your documentation (prefixed by header) forms a group. Unlike for help, all block are used in interactive mode. Suppose you have following example:

# Testing class
#
# == Parameters:
#
# $one::    number one
#
# == Advanced parameters:
#
# $two::    number two
#
# === Advanced A:
#
# $two_a::  2_a
#
# === Advanced 2_b
#
# $two_b::  2_b
#
# == Extra parameters:
#
# $three::  number three

When you enter Testing class module in interactive mode you see parameters from Basic group and options to configure parameters which belongs to rest of groups on same level, in this case Advanced and Extra parameters.

Module foreman configuration
1. Enable/disable foreman module, current value: true
2. Set one, current value: '1'
3. Configure Advanced parameters
4. Configure Extra parameters
5. Back to main menu

When you enter Extra paramaters, you see only $three and option to get back to parent. In Advanced you see $two and two more subgroups - Advanced A and Advanced B. When you enter these subgroups, you see their parameters of course. Nesting is unlimited. Also there's no naming rule. Just notice that the main group must be called Parameters and it's parameters are always displayed on first level of module configuration.

Group Extra parameters (of module foreman)
1. Set two_b, current value: '2b'
2. Back to parent menu

If there's no primary group a new one is created for you and it does not have any parameter. This mean when user enters module configuration he or she will see only subgroups in menu (no parameters until a particular subgroup is entered). If there is no group in documentation a new primary group is created and it holds all module parameters (there are no subgroups in module configuration).

Conditional parameters in interactive mode

You can also define conditions to parameter and their groups. These conditions are evaluated in interactive mode and based on the result they are displayed to the user. You can use this for example to hide mysql_* parameters when $db_type is not set 'mysql'. Let's look at following example

# Testing class
#
# == Parameters:
#
# $use_db::                  use database?
#                            type:boolean
#
# == Database parameters:    condition: $use_db
#
# $database_type::           mysql/sqlite
#
# === MySQL:                 condition: $database_type == 'mysql'
#
# $remote::                  use remote connection
#                            type:boolean
# $host                      server to connect to
#                            condition: $remote
# $socket                    server to connect to
#                            condition: !$remote

Here you can see we defined several conditions on group and parameter level. You can write condition in ruby language. All dollar-prefixed words are be substituted by value of a particular puppet parameter.

Note that conditions are combined using && when you nest them. So these are facts based on example:

• $database_type, $remote, $host, $socket are displayed only when $use_db is set to true
• $remote, $host, $socket are displayed only when $database_type is set to 'mysql'
• $host is displayed only if $remote is set to true, $socket is displayed otherwise

Here's explanation how conditions are constructed

-----------------------------------------------------------------------------
| parameter name | resulting condition                                      |
-----------------------------------------------------------------------------
| $use_db        | true                                                     |
| $database_type | true && $use_db                                          |
| $remote        | true && $use_db && $database_type == 'mysql'             |
| $host          | true && $use_db && $database_type == 'mysql' && $remote  |
| $socket        | true && $use_db && $database_type == 'mysql' && !$remote |
-----------------------------------------------------------------------------

As already said you can use whatever ruby code, so you could leverage e.g. parentheses, &&, ||, !, and, or

Custom modules and manifest names

By default Kafo expects a common module structure. For example if you add

foreman: true

to you answer file, Kafo expects a foreman subdirectory in modules/. Also it expects that there will be init.pp which it will instantiate. If you need to change this behavior you can via mapping option in config/kafo.yaml.

Suppose we have puppet module and we want to use puppet/server.pp as our init file. Also we want to name our module as puppetmaster. We add following mapping to kafo.yaml

:mapping:
  :puppetmaster:                # a module name, so we'll have puppetmaster: true in answer file
    :dir_name: 'puppet'         # the subdirectory in modules/
    :manifest_name: 'server'    # manifest filename without .pp extension

Note that if you add mapping you must enter both dir_name and manifest_name even if one of them is default.

Validations

If you specify validations of parameters in you init.pp manifest they will be executed for your values even before puppet is run. In order to do this you must follow few rules however:

• you must use standard validation functions (e.g. validate_array, validate_re, ...)
• you must have stdlib in modules directory

Enabling or disabling module

You can enable or disable module specified in answers.yaml file. Every module automatically adds two options to foreman-installer script. For module foreman you have two flag options --enable-foreman and --no-enable-foreman.

When you disable a module all its answers will be removed and module will be set to false. When you reenable the module you'll end up with default values.

Special values for arguments

Sometimes you may want to enforce undef value for a particular parameter. You can set this value by specifying UNDEF string e.g.

bin/foreman-installer --foreman-db-password=UNDEF

It also works in interactive mode.

Hooks

You may need to add new features to the installer. Kafo provides simple hook mechanism that allows you to run custom code just before and after the puppet is ran. Let's assume we want to add --reset-foreman-db option to our foreman-installer. We add following lines to generated installer script

require 'kafo/hooking'

# functions specific to foreman installer
KafoConfigure.app_option '--reset-foreman-db',
  :flag, 'Drop foreman database first? You will lose all data!', :default => false

KafoConfigure.hooking.register_pre(:reset_db) do |kafo|
  if kafo.config.app[:reset_foreman_db] && !kafo.config.app[:noop]
    `which foreman-rake > /dev/null 2>&1`
    if $?.success?
      KafoConfigure.logger.info 'Dropping database!'
      output = `foreman-rake db:drop 2>&1`
      KafoConfigure.logger.debug output.to_s
      unless $?.success?
        KafoConfigure.logger.warn "Unable to drop DB, ignoring since it's not fatal, output was: '#{output}''"
      end
    else
      KafoConfigure.logger.warn 'Foreman not installed yet, can not drop database!'
    end
  end
end

Note that we can access other installer options using kafo.config.app. Since kafo is KafoConfigure instance, you can even access puppet params values. Last but not least you have access to logger.

You can register as many hooks as you need. They are executed in unspecified order. Every hook must have a unique name. In a very similar way you can register :post hooks that are executed right after puppet run is over.

Custom paths

Usually when you package your installer you want to load files from specific paths. In order to do that you can use following configuration options:

• :answer_file: /etc/kafo/kafo.yaml
• :installer_dir: /usr/share/kafo/
• :modules_dir: /usr/share/foreman-installer/modules
• :kafo_modules_dir: /usr/share/kafo/modules

Answer file is obvious. Installer dir is a place where you installer is installed. E.g. system checks will be loaded from here (under checks subdirectory). You can optionally change foreman-installer modules dir using modules_dir option.

On debian systems you may want to specify kafo modules dir independent on your installer location. If you specify this option kafo internal installer puppet modules will be loaded from here.

Order of puppet modules execution

When you have more than one module you may end up in situation where you need specific order of execution. It seems as a puppet antipattern to me however there may be cases where it's needed. You can set order in config/kafo.yaml like this

order:
  - foreman
  - foreman_proxy

If you have other modules in your answer file they will be executed after those that have explicit order. Their order is not be specified.

Changing of log directory and user/group

By default kafo logs every run to a separate file in /var/log/kafo. You probably want to put your installation logs alongside with other logs of your application. That's why kafo has its own configuration file in which you can tune details like this.

In order to do that create a configuration file in config/kafo.yaml. You can use config/kafo.yaml.example as a template. If config/kafo.yaml does not exist default values will be used.

As a developer you can appreciate more verbose log. You can set debug level in config/kafo.yml. Also you can change a user or group that will own the log file. This is usefull if your installer requires to be run under root but you want the logs to be readable by specific users.

System checks

When you want to make sure that user has some software installed or has the right version you can write a simple script and put it into checks directory. All files found there will be ran and if any has non-zero exit code, kafo wont execute puppet.

Everything on STDOUT and STDERR is logged in error level.

Example shell script which checks java version

#!/bin/sh
java -version 2>&1 | grep OpenJDK
exit $?

Exit code

Kafo can terminate either before or after puppet is ran. Puppet is ran with --detailed-exitcodes and Kafo returns the same exit code as puppet does. If kafo terminates after puppet run exit codes are:

• '1' means there were parser/validation errors
• '2' means there were changes,
• '4' means there were failures during the transaction,
• '6' means there were both changes and failures.

Other exit codes that can be returned:

• '0' means everything went fine no changes were made
• '20' means your system does not meet configuration criteria (system checks failed)
• '21' means your answer file contains invalid values
• '22' means that puppet modules contains some error (e.g. missing documentation)
• '23' means that you have no answer file
• '24' means that your answer file asks for puppet module that you did not provide
• '25' means that kafo could not get default values from puppet

License

This project is licensed under the GPLv3+.