docs on development

docs/development.md

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+# Development
+
+## Installing from sources
+
+If you want to install the plugin from sources:
+
+```bash
+git clone https://github.com/fgrehm/vagrant-cachier.git
+cd vagrant-cachier
+bundle install
+bundle exec rake build
+vagrant plugin install pkg/vagrant-cachier-VERSION.gem
+```
+
+
+## Sanity checks
+
+There are also some [Bats](https://github.com/sstephenson/bats) tests that basically
+acts as a [sanity check](https://github.com/fgrehm/vagrant-cachier/blob/master/spec/acceptance/sanity_check.bats)
+that you can run with `bats spec/acceptance` in case you are planning to submit a
+Pull Request :) Just keep in mind that it might take a while to run if you are
+using the default VirtualBox provider.
+
+
+## How to create a new bucket?
+
+The concept of a cache _bucket_ is pretty simple to understand, we basically symlink a folder under the guest's `/tmp/vagrant-cache` into the folder where other tools keep downloaded packages. For example, in the case of the [apt bucket](https://github.com/fgrehm/vagrant-cachier#apt), we symlink `/var/cache/apt/archives` to `/tmp/vagrant-cache/apt` so that `.deb` packages downloaded with `apt-get install` can be reused when bringing machines up from scratch.
+
+If you want to see some other package manager supported, you'll first need to know if it has some sort of caching in place, where does it get stored and if it needs some extra configuration. For some managers that path will be fixed (like the canonical apt bucket), for others you might need to read some configuration by [running a command](https://github.com/fgrehm/vagrant-cachier/blob/master/lib/vagrant-cachier/cap/linux/rvm_path.rb#L10) on the guest VM (like [rvm](https://github.com/fgrehm/vagrant-cachier#rvm)) and you might even to [tweak some configs](https://github.com/fgrehm/vagrant-cachier/blob/master/lib/vagrant-cachier/bucket/yum.rb#L20) on the guest (like the [yum](https://github.com/fgrehm/vagrant-cachier#yum) bucket)
+
+There's currently a lot of duplication around the "installation" of cache buckets so there's plenty of source code for you to read in order to understand how things work under the hood but if you don't feel comfortable reading / writing Ruby code you can provide a high level overview of how to do things using plain old bash.
+
+For example, if you were to explain how to set up the rvm bucket, the script below should give vagrant-cachier maintainers an overview of how to set things up:
+
+```bash
+# Check is rvm is installed
+if ! $(rvm info > /dev/null); then
+  exit 0
+fi
+
+# If it is installed, read the cache dir
+RVM_CACHE="${rvm_path}/archives"
+
+# "Install" the bucket!
+mkdir -p /tmp/vagrant-cache/rvm/archives
+ln -s /tmp/vagrant-cache/rvm/archives $RVM_CACHE
+```