module ChefUtils::DSL::Which

Public Instance Methods

where (*cmds, prepend_path: nil, extra_path: nil, &block)

Source

# File lib/chef-utils/dsl/which.rb, line 81
def where(*cmds, prepend_path: nil, extra_path: nil, &block)
  extra_path ||= __extra_path
  paths = Array(prepend_path) + __env_path.split(File::PATH_SEPARATOR) + Array(extra_path)
  paths.uniq!
  exts = ENV["PATHEXT"] ? ENV["PATHEXT"].split(";") : []
  exts.unshift("")
  cmds.map do |cmd|
    paths.map do |path|
      exts.map do |ext|
        filename = File.join(path, "#{cmd}#{ext}")
        filename if __valid_executable?(filename, &block)
      end.compact
    end
  end.flatten
end

Lookup all the instances of an an executable that can be found through the systems search PATH. Allows specifying an array of executables to look for. All the instances of the first executable that is found will be returned first. The extra_path will override any default extra_paths which are added (allowing the user to pass an empty array to remove them).

When passed a block the block will be called with the full pathname of any executables which are found, and the block should return truthy or falsey values to further filter the executable based on arbitrary criteria.

This helper can be used in target mode in chef or with train using the appropriate wiring externally.

@example Find all the python executables, searching through the system PATH plus additionally

       the "/usr/libexec" directory, which have the dnf libraries installed and available.

cmds = where("platform-python", "python", "python3", "python2", "python2.7", extra_path: "/usr/libexec") do |f|
  shell_out("#{f} -c 'import dnf'").exitstatus == 0
end

@param [Array<String>] list of commands to search for @param [String,Array<String>] array of paths to look in first @param [String,Array<String>] array of extra paths to search through @return [String] the first match

which (*cmds, prepend_path: nil, extra_path: nil, &block)

Source

# File lib/chef-utils/dsl/which.rb, line 53
def which(*cmds, prepend_path: nil, extra_path: nil, &block)
  where(*cmds, prepend_path: prepend_path, extra_path: extra_path, &block).first || false
end

Lookup an executable through the systems search PATH. Allows specifying an array of executables to look for. The first executable that is found, along any path entry, will be the preferred one and returned first. The extra_path will override any default extra_paths which are added (allowing the user to pass an empty array to remove them).

This is syntactic sugar for ‘where(…).first`

This helper can be used in target mode in chef or with train using the appropriate wiring externally.

@example Find the most appropriate python executable, searching through the system PATH

       plus additionally the "/usr/libexec" directory, which has the dnf libraries
       installed and available.

cmd = which("platform-python", "python", "python3", "python2", "python2.7", extra_path: "/usr/libexec") do |f|
  shell_out("#{f} -c 'import dnf'").exitstatus == 0
end

Private Instance Methods

__extra_path ()

Source

# File lib/chef-utils/dsl/which.rb, line 103
def __extra_path
  nil
end

This is for injecting common extra_paths into the search PATH. The chef-client codebase overrides this into its own custom mixin to ensure that /usr/sbin, /sbin, etc are in the search PATH for chef-client.

@api private

__valid_executable? (filename) { |filename| ... }

Source

# File lib/chef-utils/dsl/which.rb, line 110
def __valid_executable?(filename, &block)
  is_executable =
    if __transport_connection
      __transport_connection.file(filename).stat[:mode] & 1 && !__transport_connection.file(filename).directory?
    else
      File.executable?(filename) && !File.directory?(filename)
    end
  return false unless is_executable

  block ? yield(filename) : true
end

Windows compatible and train/target-mode-enhanced helper to determine if an executable is valid.

@api private