module Epi

Constants

DEFAULT_LEVEL
ROOT
VERSION

Public Class Methods

launch(command, env: {}, user: nil, cwd: nil, stdout: true, stderr: true) click to toggle source

Run a system command in the background, and allow it to keep running after Ruby has exited. @param command [String|Array] The command to run, either as a pre-escaped string,

or an array of non-escaped strings (a command and zero or more arguments).

@param env [Hash] Environment variables to be passed to the command, in addition

to those inherited from the current environment

@param user [String|NilClass] If supplied, command will be run through ‘su` as

this user.

@param cwd [String|NilClass] If supplied, command will be run from this

directory.

@param stdout [String|TrueClass|FalseClass|NilClass] Where to redirect standard

output; either a file path, or `true` for no redirection, or `false`/`nil` to
redirect to `/dev/null`

@param stderr [String|TrueClass|FalseClass|NilClass] Where to redirect standard

error; either a file path, or `true` for no redirection, or `false`/`nil` to
redirect to `/dev/null`

@return [Fixnum] The PID of the started process

# File lib/epi/launch.rb, line 19
def self.launch(command, env: {}, user: nil, cwd: nil, stdout: true, stderr: true)

  # Prevent hang-up
  cmd = 'nohup '

  # The main command and its arguments
  if String === command

    # Pre-escaped string
    cmd << command
  else

    # Command and arguments that need to be escaped
    command.each { |part| cmd << ' ' << escape(part) }
  end

  # STDOUT and STDERR redirection
  {:>> => stdout, :'2>>' => stderr}.each do |arrow, dest|
    cmd << " #{arrow} #{dest || '/dev/null'}" unless TrueClass === dest
  end

  # Run in background, and return PID of backgrounded process
  cmd << ' & echo $!'

  # Include `su` command if a user is given
  cmd = "su #{user} -c #{escape cmd}" if user

  # Include the working directory
  cmd = "cd #{escape cwd} && (#{cmd})" if cwd

  # Convert environment variables to strings, and merge them with the current environment
  env = ENV.to_h.merge(env).map { |k, v| [k.to_s, v.to_s] }.to_h

  logger.debug "Starting `#{cmd}`"

  # Run the command and read the resulting PID from its STDOUT
  IO.popen(env, cmd) { |p| p.read }.to_i.tap do |pid|
    logger.info "Process #{pid} started: #{`ps -p #{pid} -o command=`.chomp}"
  end
end

logger() click to toggle source

# File lib/epi/logging.rb, line 7
def logger
  @logger ||= make_logger
end

logger=(value) click to toggle source

# File lib/epi/logging.rb, line 11
def logger=(value)
  @logger = Logger === value ? value : make_logger(value)
end

root?() click to toggle source

# File lib/epi.rb, line 27
def root?
  @is_root = `whoami`.chomp == 'root' if @is_root.nil?
  @is_root
end

Private Class Methods

default_log_path() click to toggle source

# File lib/epi/logging.rb, line 23
def default_log_path
  Data.home.join('epi.log').to_s
end

escape(*args) click to toggle source

# File lib/epi/launch.rb, line 62
def self.escape(*args)
  Shellwords.escape *args
end

log_level() click to toggle source

# File lib/epi/logging.rb, line 27
def log_level
  Logger::Severity.const_get (ENV['EPI_LOG_LEVEL'] || DEFAULT_LEVEL).upcase
end

make_logger(target = nil) click to toggle source

# File lib/epi/logging.rb, line 17
def make_logger(target = nil)
  Logger.new(target || ENV['EPI_LOG'] || default_log_path).tap do |logger|
    logger.level = log_level
  end
end