2012-01-11 20:59:21 -08:00

126 lines
4.3 KiB
Ruby

require "pathname"
require "log4r"
module Vagrant
module Config
# This class is responsible for loading Vagrant configuration,
# usually in the form of Vagrantfiles.
#
# Loading works by specifying the sources for the configuration
# as well as the order the sources should be loaded. Configuration
# set later always overrides those set earlier; this is how
# configuration "scoping" is implemented.
class Loader
# This is an array of symbols specifying the order in which
# configuration is loaded. For examples, see the class documentation.
attr_accessor :load_order
def initialize
@logger = Log4r::Logger.new("vagrant::config::loader")
@sources = {}
@proc_cache = {}
@config_cache = {}
end
# Set the configuration data for the given name.
#
# The `name` should be a symbol and must uniquely identify the data
# being given.
#
# `data` can either be a path to a Ruby Vagrantfile or a `Proc` directly.
# `data` can also be an array of such values.
#
# At this point, no configuration is actually loaded. Note that calling
# `set` multiple times with the same name will override any previously
# set values. In this way, the last set data for a given name wins.
def set(name, sources)
@logger.debug("Set #{name.inspect} = #{sources.inspect}")
# Sources should be an array
sources = [sources] if !sources.kind_of?(Array)
# Gather the procs for every source, since that is what we care about.
procs = []
sources.each do |source|
if !@proc_cache.has_key?(source)
# Load the procs for this source and cache them. This caching
# avoids the issue where a file may have side effects when loading
# and loading it multiple times causes unexpected behavior.
@logger.debug("Populating proc cache for #{source.inspect}")
@proc_cache[source] = procs_for_source(source)
end
# Add on to the array of procs we're going to use
procs.concat(@proc_cache[source])
end
# Set this source by name.
@sources[name] = procs
end
# This loads the configured sources in the configured order and returns
# an actual configuration object that is ready to be used.
def load
@logger.debug("Loading configuration in order: #{@load_order.inspect}")
unknown_sources = @sources.keys - @load_order
if !unknown_sources.empty?
# TODO: Raise exception here perhaps.
@logger.error("Unknown config sources: #{unknown_sources.inspect}")
end
# Create the top-level configuration which will hold all the config.
result = Top.new
@load_order.each do |key|
next if !@sources.has_key?(key)
@sources[key].each do |proc|
if !@config_cache.has_key?(proc)
@logger.debug("Loading from: #{key} (evaluating)")
current = Top.new
proc.call(current)
@config_cache[proc] = current
end
# Merge in the results of this proc's configuration
result = result.merge(@config_cache[proc])
end
end
@logger.debug("Configuration loaded successfully")
result
end
protected
# This returns an array of `Proc` objects for the given source.
# The `Proc` objects returned will expect a single argument for
# the configuration object and are expected to mutate this
# configuration object.
def procs_for_source(source)
return [source] if source.is_a?(Proc)
# Assume all string sources are actually pathnames
source = Pathname.new(source) if source.is_a?(String)
if source.is_a?(Pathname)
@logger.debug("Load procs for pathname: #{source.inspect}")
begin
return Config.capture_configures do
Kernel.load source
end
rescue SyntaxError => e
# Report syntax errors in a nice way.
raise Errors::VagrantfileSyntaxError, :file => e.message
end
end
raise Exception, "Unknown configuration source: #{source.inspect}"
end
end
end
end