[Docs] Added a readme. (See #1)

![relayd](docs/assets/logo-project.png)

This project targets the control of mutliple relays via HTTP. With the help of

this daemon you can fetch the current status of all relays or just one

specific. You are also able to turn a specific relay on and off. More comfort

comes with the ability to toggle the state of a relay without knowing the

current state.

- [About the setup](#about-the-setup)

- [Requirements](#requirements)

- [Installation](#installation)

  - [From Source](#from-source)

  - [Arch Linux Packaging](#arch-linux-packaging)

- [Configuration](#configuration)

  - [Service](#service)

  - [Process management](#process-management)

- [Development](#development)

## About the setup

The project runs productive on a [Raspberry Pi Model B rev2][] with [Arch Linux

ARM][] as distribution. It controls multiple [2 Channel 5V Relays][].

## Requirements

The project needs the following libraries to build:

* [glibc](https://www.gnu.org/software/libc/) (>=2.20)

* [openssl](https://www.openssl.org/) (>=1.0.1.l)

* [libconfig](http://www.hyperrealm.com/libconfig/) (>=1.5)

* [libbcm2835](http://www.airspayce.com/mikem/bcm2835/) (>=1.46)

* [libmicrohttpd](https://www.gnu.org/software/libmicrohttpd/) (>=0.9.44)

The versions behind the libraries are describing the lowest tested versions. Is it

possible that lower and/or higher versions will run fine, too.

The project was successfully compiled with the [GCC](https://gcc.gnu.org/) (>=4.9.2).

## Installation

### From Source

For all non-Arch Linux systems you can install the software the old way by

building it from source (`make build`) and fire a `make install`. The project

is not configured by autotools, but the makefiles makes use of the [standard

directory variables][]. Forthermore you can specify a `DESTDIR` variable for

packaging.  (`make DESTDIR=/tmp/xyz install`) If you are interessested in

changing the default directory variables consider the [Makefile.shared

file](Makefile.shared). They are change able the same way as `DESTDIR`. The

`uninstall` target takes care of the same variables and will cleanup your

system if you don't want the software to be installed.

:warning: This process expects you to build the software on the same

architecture as it will run on. For cross compiling consider a related guide

for your target architecture.

### Arch Linux Packaging

If you are interessested in building an Arch Linux package, all you have to do

is to clone this repository, install/build all the dependencies of the project

and run `makepkg` inside the `dist/archlinux` directory. Afterwards you will

find a fresh package (`relayd-*-*.pkg.tar.xz`) in the same

directory. This process underlies the same cross compiling restrictions as the

[From Source](#from-source) installation.

## Configuration

### Service

The [relayd][] daemon can be configured with a configuration file

which follows the format which is described by the [relayd.conf][]

man page.  On Arch Linux the system wide configuration can be found at

`/etc/relayd.conf`.

### Process management

The [relayd][] daemon can be started in different flavors. It is

able to run in foreground by adding the `-f|--foreground` parameters or in

background (without additional parameters).  While the daemon is running in

foreground, all logging outputs will be printed to `stdout` and/or `stderr`.

The foreground logging is prefixed with the current date/time and the log level

for the message. While the daemon runs in background, all logging outputs will

be redirected to `syslog`.  For Arch Linux there is a systemd unit file shipped

for the daemon. The service can be enabled with:

`sudo systemctl enable relayd.service`.

## Development

The project is written in C and comes with a bulk of predefined GNU Make

targets to speed up common development tasks. To get in touch just fork and

clone the project, install/build the required dependencies and fire a `make build`.

The most adorable targets are `clean build test` (in this order :)). While

editing the man pages you can easily review the latest state with the `docs-*`

targets. (currently there are:

`docs-relayd.1 docs-relayd.conf.5`)

Please mind the [Contribution Guide][] and the given [.editorconfig file][] if

you plan to work on the project.

[relayd]: ../../wikis/man/relayd.1.html

[relayd.conf]: ../../wikis/man/relayd.conf.5.html

[Contribution Guide]: CONTRIBUTING.md

[.editorconfig file]: .editorconfig

[standard directory variables]: https://www.gnu.org/prep/standards/html_node/Directory-Variables.html

[Raspberry Pi Model B rev2]: https://www.raspberrypi.org

[Arch Linux ARM]: http://archlinuxarm.org/

[2 Channel 5V Relays]: http://www.amazon.de/gp/product/B00AE1P8KM?psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00