vagrant-gatling-rsync

An rsync watcher for Vagrant 1.5+ that uses fewer host resources at the potential cost of more rsync actions.

Authors

Steven Merrill (@stevenmerrill) originally had the idea to tap into rb-fsevent and rb-inotify to more efficiently rsync files.

Doug Marcey (@dougmarcey) provided considerable guidance in the implementation of the coalescing functionality and wrote the initial sketch of the Linux and Windows adapters.

Why "gatling"?

The gatling gun was the first gun capable of firing continuously.

This plugin

The built-in rsync-auto plugin sometimes uses a lot of CPU and disk I/O when it starts up on very large rsynced directories. This plugin is designed to work well with such large rsynced folders.

The rsync-auto command that ships with Vagrant 1.5 uses the listen gem. The Listen gem is quite thorough - it uses Celluloid to spin up an actor system and it checks file contents on OS X to ensure that running "touch" on a file (to do a write but not update its content) will not fire the rsync command.

The downside of using Listen is that it takes a large amount of host resources to monitor large directory structures. This gem works well with to monitor directories hierarchies with 10,000-100,000 files.

This gem's implementation is much closer to the underlying fsevent or inotify APIs, which allows for higher performance.

Event coalescing

This plugin also coalesces events for you. The default latency is 1.5 seconds. (This will be a configurable option in future versions.) If you specify a latency of two seconds, this plugin will not fire a vagrant rsync until two contiguous seconds without file events have passed. This will delay rsyncs from happening if many writes are happening on the host (during a make or a git clone, for example) until the activity has leveled off.

Working with this plugin

Add the following information to the Vagrantfile to set the coalescing threshold in seconds. If you do not set it, it will default to 1.5.

You will also need to have at least one synced folder set to type "rsync" to use the plugin.

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
  config.vm.box = "hashicorp/precise64"

  config.vm.synced_folder "../files", "/opt/vagrant/rsynced_folder", type: "rsync",
    rsync__exclude: [".git/", ".idea/"]

  # Configure the window for gatling to coalesce writes.
  config.gatling.latency = 2.5
end

With the Vagrantfile configured in this fashion, you can run the following command to sync files.

vagrant gatling-rsync-auto