Updated docs

docs/sources/installation/docker.md

@@ -6,4 +6,29 @@ page_keywords: grafana, installation, docker, container, guide
 
 # Installing using Docker
 
+## Install from offical docker image
+
+Grafana has an offical docker container.
+
+    $ docker run -i -p 3000:3000 grafana/grafana
+
+All grafana configuration settings can be defined using ENVIRONMENT variables, this is especially useful when using the
+above container.
+
+## Docker volumes & ENV config
+
+The docker container exposes two volumes, the sqlite3 database in the folder `/opt/grafana/data` and
+configuration files in the `/opt/grafana/conf` folder. You can map these volumes to host folders when you start the container:
+
+    $ docker run -d -p 3000:3000 \
+        -v /var/grafana/data:/opt/grafana/data \
+        -e "GF_SECURITY_ADMIN_PASSWORD=secret  \
+        grafana/grafana:develop
+
+In the above example I map the data folder and set a config option via an `ENV` variable.
+
+## Configuration
+
+The backend web server has a number of configuration options. Go the [Configuration](configuration) page for details
+on all those options.