EasyServe

Framework for starting tcp/unix services and connected clients under one parent process and on remote hosts.

EasyServe takes the headache out of:

Choosing unused unix socket paths and tcp ports.
Starting service processes with open server sockets, and handing off connections to user code.
Storing a services file (yaml) listing service addresses, represented as unix socket path or tcp address and port.
Ensuring that tcp service addresses will make sense from remote networks, to the extent possible.
Reading the services file locally or remotely over ssh.
Setting up client connections and handing off sockets to user code in each client, whether child process or remote, whether unix or tcp.
Tunneling connections over ssh, if desired.
Working around poor support for dynamic port forwarding in old versions of OpenSSH.
Working around a race condition in an old version of OpenSSH.
Choosing between -L and -R styles of tunneling, depending on whether the remote process starts independently of the services.
Avoiding race conditions in the service setup phase.
Propagating log settings among all distributed clients (defaulting to a minimal format more readable than the usual default).
Pushing script code to remote ruby instances.
Pulling remote log messages and backtraces back into local log message stream.
Protecting services from interrupt signals when running interactively.
Stopping "passive" clients when they are no longer needed (by "active" clients).
Cleaning up.

Combine with other libraries for the functionality that EasyServe does not provide:

Protocols built on top of sockets.
Daemonization.
IO multiplexing, concurrency, asynchrony, etc.
Process supervision and monitoring.
Config management and distribution.
Code distribution.

Use cases

Start some processes with unix sockets established among them and clean up afterwards: simple and multi
Ditto but with tcp and possibly remote
Ditto but through ssh tunnels
Ditto but where the tunnel is set up by the remote client, without special assistance from the server examples/tunnel
Useful for all-in-one-file examples of client-server libraries
Tupelo: a distributed programming framework using easy-serve.

Installation

Requires ruby 2.0 or later. Install easy-serve as gem:

gem install easy-serve

Synopsis

require 'easy-serve'

EasyServe.start do |ez|
  ez.log.level = Logger::ERROR

  ez.start_services do
    ez.service "echo", :unix do |svr|
      Thread.new do
        loop do
          conn = svr.accept
          msg = conn.read
          puts msg
          conn.write "echo #{msg}"
          conn.close_write
        end
      end
    end
  end

  ez.child "echo" do |echo_conn|
    echo_conn.write "hello from client"
    echo_conn.close_write
    puts echo_conn.read
  end
end

Output:

hello from client
echo hello from client

Contact

Joel VanderWerf, vjoel@users.sourceforge.net, @JoelVanderWerf.

License and Copyright