Capistrano 2.0 rsync_remote_cache Deployment Strategy

Description

This gem provides a deployment strategy for Capistrano which combines the rsync command with a remote cache, allowing fast deployments from SCM repositories behind firewalls.

Aim

The original gem is outdated. In this gem, I have merged all the pull requests that were interesting, such as rsync in parallel, rsh parameters, etc.

Original gem

For the original gem, visit: github.com/vigetlabs/capistrano_rsync_with_remote_cache

Installation

gem install capistrano-rsync-remote-cache

Usage

To use this deployment strategy, add this line to your deploy.rb file:

set :deploy_via, :rsync_remote_cache

If you want to enable the parallel deployment:

set :rsync_in_parallel, true

If you want to tune the number of threads:

set :rsync_concurrency, 8

By default, the deployments spawns 8 threads.

Under the Hood

This strategy maintains two cache directories:

  • The local cache directory is a checkout from the SCM repository. The local cache directory is specified with the :local_cache variable in the configuration. If not specified, it will default to .rsync_cache in the same directory as the Capfile.

  • The remote cache directory is an rsync copy of the local cache directory. The remote cache directory is specified with the :repository_cache variable in the configuration (this name comes from the :remote_cache strategy that ships with Capistrano, and has been maintained for compatibility.) If not specified, it will default to shared/cached-copy (again, for compatibility with remote_cache.)

Deployment happens in three major steps. First, the local cache directory is processed. There are three possibilities:

  • If the local cache does not exist, it is created with a checkout of the revision to be deployed.

  • If the local cache exists and matches the :repository variable, it is updated to the revision to be deployed.

  • If the local cache exists and does not match the <p>:repository</p> variable, the local cache is purged and recreated with a checkout of the revision to be deployed.

  • If the local cache exists but is not a directory, an exception is raised

Second, rsync runs on the local side to sync the remote cache to the local cache. When the rsync is complete, the remote cache should be an exact replica of the local cache.

Finally, a copy of the remote cache is made in the appropriate release directory. The end result is the same as if the code had been checked out directly on the remote server, as in the default strategy.