Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Browse files

Documentation and licensing info

Prepping for release to github
  • Loading branch information...
commit b143c42798d56546a3f24313b252e7f43d352c69 1 parent 8c16d73
@jamis jamis authored
Showing with 99 additions and 0 deletions.
  1. +1 −0  .gitignore
  2. +20 −0 LICENSE
  3. +65 −0 README.rdoc
  4. +13 −0 recipes/cached_externals.rb
View
1  .gitignore
@@ -0,0 +1 @@
+*.swp
View
20 LICENSE
@@ -0,0 +1,20 @@
+Copyright (c) 2008 by 37signals, LLC
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
View
65 README.rdoc
@@ -0,0 +1,65 @@
+= Cached Externals
+
+This Capistrano extension provides yet another way to manage your application's external dependencies.
+
+External dependencies are a necessary evil. If you're doing Rails development, you'll automatically be dependent on the Rails framework itself, at the very least, and you probably have a handful or two of plugins that you're using as well. Traditionally, the solution to these has been to either install those dependencies globally (which breaks down when you have multiple apps that need different versions of Rails or the plugins), or to bundle them into your application directly via freeze:gems or the like (which tends to bloat your repository).
+
+Now, bloating a repository is, in itself, not a big deal. However, when it comes time to deploy your application, more data in the repository means more data to check out, resulting in longer deploy times. Some deployment strategies (like remote_cache) can help, but you're _still_ going to be copying all of that data every time you deploy your application.
+
+One solution is to use a deployment strategy like FastRemoteCache (http://github.com/37signals/fast_remote_cache), which employs hard-links instead of copying files. But your deploys will go _even faster_ if you didn't have to worry about moving or linking all the files in your external dependencies.
+
+That's where this Cached Externals plugin comes in. It capitalizes on one key concept: your external dependencies are unlikely to change frequently. Because they don't change frequently, it makes more sense to just check them out once, and simply refer to that checkout via symlinks.
+
+This means your deploys only have to add a single symbolic link for each external dependency, which can mean orders of magnitude less work for a deploy to do.
+
+== Dependencies
+
+* Capistrano 2 or later (http://www.capify.org)
+
+== Assumptions
+
+The Cached Externals plugin assumes that your external dependencies are under version control somewhere, and the repositories are accessible both locally and from your deployment targets.
+
+== Usage
+
+When using this with Rails applications, all you need to do is install this as a plugin in your application. Make sure your Capfile has a line like the following:
+
+ Dir['vendor/plugins/*/recipes/*.rb'].each { |plugin| load(plugin) }
+
+It should be just before the line that loads the 'config/deploy' file. If that line is not there, add it (or rerun "capify .").
+
+If you are not using this with a Rails application, you'll need to explicitly load recipes/cached_externals.rb in your Capfile.
+
+Next, tell Capistrano about your external dependencies. This is done via a YAML file: config/externals.yml. It describes a hash of path names that describe the external repository. For example:
+
+ ---
+ vendor/rails:
+ :type: git
+ :repository: git://github.com/rails/rails.git
+ :revision: f2d8d13c6495f2a9b3bbf3b50d869c0e5b25c207
+ vendor/plugins/exception_notification:
+ :type: git
+ :repository: git://github.com/rails/exception_notification.git
+ :revision: ed0b914ff493f9137abc4f68ee08e3c3cd7a3211
+
+Specify as many as you like. Although it is best to specify an exact revision, you can also give any revision identifier that capistrano understands (git branches, HEAD, etc.). If you do, though, Capistrano will have to resolve those pseudo-revision identifiers every time, which can slow things down a little.
+
+Once you've got your externals.yml in place, you'll need to clear away the cruft. For example, if you were going to put vendor/rails as a cached external dependency, you'd need to first remove vendor/rails from your working copy. After clearing away all of the in-repository copies of your external dependencies, you just tell capistrano to load up the cached copies:
+
+ cap local externals:setup
+
+That will cause Capistrano to read your externals.yml, checkout your dependencies, and create symlinks to them. When run locally like that, the dependencies will be checked out to ../shared/externals (e.g., up a directory from your project root).
+
+Any time you update your config/externals.yml, you'll need to rerun that command. If an external hasn't changed revision, Capistrano will notice that and will not check it out again--only those that have changed will be updated.
+
+When you deploy your application, these externals will be checked out into #{shared_path}/externals, and again, nothing will be checked out if the dependency's revision matches what has already been cached.
+
+== Tips
+
+For the fastest possible deploys, always give an exact revision identifier. This way, Capistrano may not have to query the dependency's repository at all, if nothing has changed.
+
+Also, if you're using git, it can be a pain to change branches with this plugin, because different branches may have different dependencies, or (even worse) the same dependency but at different revisions. This plugin provides a Rake task, "git:hooks:install", that installs a couple of git hook scripts: post-checkout and post-merge. (If you already have scripts defined for those, back them up before running this task, because they'll get clobbered!) These hooks will then make it so that any time you switch branches, or do a "git pull" or "git merge", the "cap local externals:setup" task will also get run, keeping your external dependencies in sync.
+
+== License
+
+This code is released under the MIT license, and is copyright (c) 2008 by 37signals, LLC. Please see the accompanying LICENSE file for the full text of the license.
View
13 recipes/cached_externals.rb
@@ -1,3 +1,16 @@
+# ---------------------------------------------------------------------------
+# This is a recipe definition file for Capistrano. The tasks are documented
+# below.
+# ---------------------------------------------------------------------------
+# This file is distributed under the terms of the MIT license by 37signals,
+# LLC, and is copyright (c) 2008 by the same. See the LICENSE file distributed
+# with this file for the complete text of the license.
+# ---------------------------------------------------------------------------
+
+# The :external_modules variable is used internally to load and contain the
+# contents of the config/externals.yml file. Although you _could_ set the
+# variable yourself (to bypas the need for a config/externals.yml file, for
+# instance), you'll rarely (if ever) want to.
set(:external_modules) do
require 'yaml'
Please sign in to comment.
Something went wrong with that request. Please try again.