Deploys your code; Does some other stuff; e.g: Capistrano Fabric Vlad the Deployer.
Capistrano = awesome; some RoR assumptions (override some of their tasks)
Doesn't deploy content, install packages, manage configs; but some overlap
Why use? Near instant, no downtime. Rollback, Version control != deployment tool.
Drush deploy is heavily influenced by Capistrano
But... we need SOMETHING in the community; most people aren't using any of the big three from a show of hands
PHP 5.3 only; git only.
Uses site alias groups: a drush feature (scripted command aliases). Also Drush options (deploy.drushrc.php)
How it works: directory of config (including releases). Releases, shared (sites/files etc. applied to every release)
Aliases:
$aliases[foo] = array(...);
$aliases[bar] = array(...);
drush -v deploy-setup @alias-file-name
Strategies - check for dependencies
Tracks releases: deploy-rollback rolls back to previous one
Tasks to run after actions e.g. something to roll back after a symlink. They prevent deploy-rollback from working.
deploy-cleanup gets rid of unused releases
Challenges = patches they sent upstream; site aliases as arguments; example in core is drush sql-sync; Concurrent remote command execution.
Options file. Examples of a ['after'] task: function foo($d) { $d->run('command-on-remote-server-here'); }
A /* @run_once */ comment makes it only run on one server in load-balanced environment
function bar($d) { $d->drush('drush-command-on-remote-server-here'); }
Strategies: use namespaces; object overriding
