New Dockerfile based on Alpine Linux and Nginx/PHP-FPM

doc/docker.markdown

@@ -2,7 +2,18 @@ How to run Kanboard with Docker?
 ================================
 
 Kanboard can run easily with [Docker](https://www.docker.com).
-There is a `Dockerfile` in the repository to build your own container.
+
+The image size is approximately **50MB** and contains:
+
+- [Alpine Linux](http://alpinelinux.org/)
+- The [process manager S6](http://skarnet.org/software/s6/)
+- Nginx
+- PHP-FPM
+
+The Kanboard cronjob is also running everyday at midnight.
+URL rewriting is enabled in the included config file.
+
+When the container is running, the memory utilization is around **20MB**.
 
 Use the stable version
 ----------------------
@@ -17,7 +28,7 @@ docker run -d --name kanboard -p 80:80 -t kanboard/kanboard:stable
 Use the development version (automated build)
 ---------------------------------------------
 
-Every new commit on the repository trigger a new build on [Docker Hub](https://registry.hub.docker.com/u/kanboard/kanboard/).
+Every new commit on the repository trigger a new build on the [Docker Hub](https://registry.hub.docker.com/u/kanboard/kanboard/).
 
 ```bash
 docker pull kanboard/kanboard
@@ -29,31 +40,45 @@ The tag **latest** is the **development version** of Kanboard, use at your own r
 Build your own Docker image
 ---------------------------
 
+There is a `Dockerfile` in the Kanboard repository to build your own image.
 Clone the Kanboard repository and run the following command:
 
 ```bash
 docker build -t youruser/kanboard:master .
 ```
 
-To run your image in background on the port 80:
+or
+
+```bash
+make docker-image
+```
+
+To run your container in background on the port 80:
 
 ```bash
 docker run -d --name kanboard -p 80:80 -t youruser/kanboard:master
 ```
 
-Store your data on a volume
----------------------------
+Volumes
+-------
 
-By default Kanboard will store attachments and the Sqlite database in the directory data. Run this command to use a custom volume path:
+You can attach 2 volumes to your container:
 
-```bash
-docker run -d --name kanboard -v /your/local/data/folder:/var/www/html/data -p 80:80 -t kanboard/kanboard:master
-```
+- Data folder: `/var/www/kanboard/data`
+- Plugins folder: `/var/www/kanboard/plugins`
+
+Use the flag `-v` to mount a volume on the host machine like described in [official Docker documentation](https://docs.docker.com/engine/userguide/containers/dockervolumes/).
+
+Config files
+------------
+
+- The container already include a custom config file located at `/var/www/kanboard/config.php`.
+- You can store your own config file on the data volume: `/var/www/kanboard/data/config.php`.
 
 References
 ----------
 
 - [Official Kanboard images](https://registry.hub.docker.com/u/kanboard/kanboard/)
 - [Docker documentation](https://docs.docker.com/)
-- [Dockerfile stable version](https://github.com/kanboard/docker/blob/master/Dockerfile)
+- [Dockerfile stable version](https://github.com/kanboard/docker)
 - [Dockerfile dev version](https://github.com/fguillot/kanboard/blob/master/Dockerfile)