Rye - v0.9¶ ↑
Safely run SSH commands on a bunch of machines at the same time (from Ruby).
Inspired by Rush and compatible with Ruby 1.8, 1.9, and JRuby 1.3+!
As of 0.9.8, all gem releases are signed. See Installation.
Rye is a Ruby abstraction for executing shell commands via SSH. By default, Rye errs on the side of caution by running in “safe-mode” which specifies a default whitelist of commands and aggressively escapes all command arguments. For example, file globs and the “rm” command are not available in safe-mode, so you can’t do this:
Rye does not require anything to be installed on the server side (other than an SSH daemon) so it can be run from any machine with Ruby, OpenSSL, and OpenSSH.
Example 1 – Execute commands on a remote machine¶ ↑
Shell commands are executed by calling methods on a Rye::Box object.
rbox = Rye::Box.new('hostname') rbox.pwd # => "/home/rye" rbox.uname :a # => "Darwin rye-stage 9.7.0 ..."
Method arguments are sent directly as arguments to the shell command. Single-character Symbols are assumed to be single-character switches. e.g.
rbox.uname :a becomes
The return value for a command is a modified Array containing the contents of STDOUT split by line. It also gives access to STDERR and the exit code
ret = rbox.uptime # => "11:02 up 16:01, 3 users" ret.stderr # =>  ret.exit_status # => 0 ret.stdout # => "11:02 up 16:01, 3 users" ret.stdout.class # => Array ret.class # => Rye::Rap
Example 2 – Paths and environment variables¶ ↑
You can change directories.
rbox.cd '/tmp' rbox.pwd # => '/tmp' rbox['/etc'].ls # => ['apache', 'init.d', ...] rbox.pwd # => '/etc' rbox.cd # => '/home/rye'
You can specify environment variables.
rbox.setenv('TIPPLE', "Forty Creek") rbox.getenv 'TIPPLE' # => "Forty Creek"
Example 3 – Adding and removing commands¶ ↑
You can add and remove commands to the whitelist.
Rye::Cmd.add_command :anything, '/usr/bin/uptime' rbox = Rye::Box.new rbox.anything Rye::Cmd.remove_command :anything rbox.anything # => Rye::CommandNotFound exception
Example 4 – Disabling Safe Mode¶ ↑
Safe mode can be disabled on one of the following ways.
rbox = Rye::Box.new 'HOST', :safe => false OR rbox.disable_safe_mode
When safe-mode is disabled, you can run any command (regardless of what is defined in the whitelist) with any valid arguments (fileglobs, tildas, etc…).
rbox.kill '-SIGHUP', 1928111 rbox.rm 'path/2/*'
You can also execute any valid shell command.
rbox.execute 'ps aux | grep ruby > /tmp/ruby-process-list'
See the “About Safe Mode” section below for more information.
Example 5a – Accessing Multiple Machines¶ ↑
Shell commands can be executed on multiple machines using a Rye::Set object. Create a “set” of machines.
rbox = Rye::Box.new 'HOST1' rset = Rye::Set.new rset.add_boxes rbox, 'HOST2' # Add boxes as hostnames or objects
Then call methods just like with Rye::Box, except now the return value is an Array of Arrays. The order of return values matches the order the machines were added to the set.
rset.hostname # => [["HOST1"], ["HOST2"]] rset.uname # => [["Darwin"], ["Linux"]]
Example 5b – Accessing Multiple Machines in Parallel¶ ↑
By default, Rye::Set connects to each machine sequentially in the order they were added to the set. Commands can also be run in parallel.
rset = Rye::Set.new "SETNAME", :parallel => true OR rset.parallel = true
Example 6 – File Transfers¶ ↑
rbox = Rye::Box.new "localhost" rbox.file_upload "README.rdoc", "/tmp" applejack = StringIO.new "Some in-memory content" rbox.file_upload applejack, "/tmp/applejack.txt" rbox.ls "/tmp/" # => [README.rdoc, applejack.txt] rbox.cat "/tmp/applejack.txt" # => "Some in-memory content" filecontent = StringIO.new rbox.file_download "/tmp/applejack.txt", filecontent filecontent.read # => "Some in-memory content"
Example 7 – Local processes¶ ↑
For local processes, you can bypass
Rye::Box and execute commands directly with
Rye.shell :uptime # => 11:02 up 16:01, 3 users
The first argument must be the command name and the remaining arguments are sent directly as arguments to the command. They’re not escaped like with
Rye::Box so you can use the asterisk, environment variables, pipes, and redirects etc. Also note that you can specify single character switches as symbols and you can separate arguments or put them into a single String.
Rye.shell :ls, '*' Rye.shell :ls, '-l $HOME' Rye.shell :ls, :l, '$HOME > $TMPDIR/crazy.txt'
The return value is a Rye::Rap object (just like with Rye::Box) so you have access to the exit code and STDERR output:
ret = Rye.shell :ls, 'nofile' ret.exit_status # => 1 ret.stderr # => "sh: nofile: No such file or directory" ret.class # => Rye::Rap
Example 8a – Hopping Firewalls¶ ↑
When working with machines that are behind another host (assuming that you have ssh access to the firewall host):
rhop = Rye::Hop.new('firewall.lan') rbox = Rye::Box.new('filibuster', :via => rhop) rbox.uptime # => 20:53 up 1 day, 1:52, 4 users Or rbox = Rye::Box.new('filibuster', :via => 'firewall.lan')
The information for the Rye::Box is then relative from the position of the firewall. So, the hostname ‘filibuster’ is used from ‘firewall.lan’
Example 8b – Hopping Firewalls, in groups¶ ↑
rset = Rye::Set.new "guarded_few", :parallel => true rhop = Rye::Hop.new "firewall.lan" rbox1 = Rye::Box.new "192.168.1.10", :via => rhop rbox2 = Rye::Box.new "192.168.1.15", :via => rhop rset.add_boxes rbox1, rbox2 rset.uptime # => [[17:17:44 up 548 days, 13:37, 20 users, load average: 0.12, 0.07, 0.06], [01:17:49 up 6 days, 1:39, 9 users, load average: 0.13, 0.09, 0.09]]
Example 9 – Disable password prompt¶ ↑
If you’re running in a terminal but you want
Net::SSH::AuthenticationFailed to be raised instead of getting a password prompt when authentication fails, set
:password_prompt option to false:
rbox = Rye::Box.new("foo.com", :user => "dan", :password => "inkorrect", :password_prompt => false) rbox.uptime # => raises Net::SSH::AuthenticationFailed
About Safe-Mode¶ ↑
You can’t use file globs. This means you can’t do this:
~also doesn’t work!
You can’t use environment variables as arguments. This means you can’t do this:
rbox.echo('$HOME'). However, environment variables are available to the commands you run.
Pipes and operators don’t work:
|, &&, >, <, ||, ~, etc…
Backticks don’t work either:
Why? In safe-mode, all command arguments are escaped which turns all arguments into their literal values.
Using a Ruby interface to execute shell commands is pretty awesome, particularly to run them on several machines simultaneously. That’s a lot of power and it’s potentially very dangerous. That’s why Rye disables this stuff by default. There’s probably a way to do it safely but it’s not obvious yet (to me). If you have any ideas, I’d love to hear them!
Command Whitelist¶ ↑
Rye permits only a limited number of system commands to be run. This default whitelist is defined in Rye::Cmd but you can add your own commands as you please (see Example 3).
OpenSSL (The C library)
$ gem install rye
or via download:
However, in order to be sure the code you’re installing hasn’t been tampered with, it’s recommended that you verify the signiture. To do this, you need to add my public key as a trusted certificate (you only need to do this once):
# Add the public key as a trusted certificate # (You only need to do this once) $ curl -O https://raw.github.com/delano/rye/master/gem-public_cert.pem $ gem cert --add gem-public_cert.pem
Then, when install the gem, do so with high security:
$ gem install rye -P HighSecurity
If you don’t add the public key, you’ll see an error like “Couldn’t verify data signature”. If you’re still having trouble let me know and I’ll give you a hand.
Kalin Harvey (rely.ca)
Mike Cline for giving the okay to use the Rye name.
Justin Case (github.com/justincase/) for fixes
Vincent Batts (hashbangbash.com/) for Rye::Hop
More Info¶ ↑
Related Projects¶ ↑
Escape, Copyright © 2006,2007 Tanaka Akira <email@example.com>
Rye::Box#instance_exec (for Ruby 1.8) Mauricio Fernandez