Update README

Add sections about installation, usage, testing and licensing.

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>

README.md

@@ -2,4 +2,83 @@
 
 This is intended to be a replacement for [KitchenCI](https://test-kitchen.chef.io/) and [kitchen-salt](https://github.com/saltstack/kitchen-salt), focussing on testing SaltStack states using Vagrant and Pytest/Testinfra.
 
+## Installation
 
+So far, a packaged installation is possible on openSUSE Tumbleweed:
+
+```
+$ zypper ar -f https://download.opensuse.org/repositories/home:/crameleon:/Scullery/openSUSE_Tumbleweed/home:crameleon:Scullery.repo
+$ zypper in scullery
+```
+
+This will pull in `vagrant`, `vagrant-libvirt`, `python3-vagrant`, `python3-pytest` and `python3-pytest-testinfra` as dependencies.
+
+Installation on Leap 15.4 is possible, however will currently cause dependency issues with the needed `python-vagrant` library.
+
+It is possible to run `scullery.py` from a Git checkout of this repository if the dependencies are resolved manually.
+
+Currently the script behaves purely as a console application and imports as a Python module are not supported.
+
+## Basic usage
+
+```
+scullery -h
+usage: scullery [-h] [--debug] [--config CONFIG] [--env] --suite SUITE [--stop | --test | --status | --refresh] [--force-stop]
+
+options:
+  -h, --help       show this help message and exit
+  --debug          Print extremely verbose output
+  --config CONFIG  Specify the configuration file to use
+  --env            Write environment file for direct use of Vagrant
+  --suite SUITE    Specify the suite to run
+  --stop           Stop running machines
+  --test           Start machines and run tests
+  --status         Get Vagrant deployment status
+  --refresh        Re-sync files and re-run bootstrap scripts
+  --force-stop     Invoke Vagrant destruction without having detected any running VM's
+```
+
+## Command line examples
+
+* To run a complete test suite:  
+  `$ scullery --suite <name of suite> --test`
+
+* To create Vagrant VM's without invoking the tests:
+  `$ scullery --suite <name of suite>`
+
+* To refresh the VM's Salt files:  
+  `$ scullery --suite <name of suite> --refresh`
+
+* To stop the VM's and tidy up:  
+  `$ scullery --suite <name of suite> --stop`
+
+## Interacting with Vagrant
+
+It is possible to directly interact with the Vagrant environment templated by Scullery. To do so, generate an environment file by adding `--env` to any command line call - for example:
+
+`$ scullery --suite <name of suite> --env`
+
+This will write a `.scullery_env` file to the current working directory. Export the environment variables in the file using your Shell, afterwards use `vagrant` like you normally would. Example for `bash`/`sh`:
+
+```
+$ set -a; . .scullery_env; set +a
+$ vagrant ssh # or any other Vagrant command
+```
+
+Do not forget to unset the exported variables before you call Scullery with a different `--suite`!
+
+## Hacking
+
+To test Scullery itself, call Pytest with your favourite arguments from the repository root:
+
+```
+$ pytest -v -rx -x tests/*.py
+```
+
+Make sure to not have _any_ other Scullery based Vagrant VM's running in the same Libvirt session and no `SCULLERY_*` or `VAGRANT_*` variables exported in your shell.
+
+The complete test suite takes about 30 minutes to execute on an Intel i7-6820HQ CPU with SSHD storage. If you want to test only certain functionality, simply add `-k <name of test function>`.
+
+## License
+
+This project is licensed under the European Union Public License found in the file `LICENSE`.