Add docs for env backend

docs/env-getting-started.md

@@ -0,0 +1,78 @@
+# Quick Start with etcd
+
+### Set some environment variables
+
+```
+export MYAPP_DATABASE_URL=db.example.com
+export MYAPP_DATABASE_USER=rob
+```
+
+### Create the confdir
+
+The confdir is where template resource configs and source templates are stored. The default confdir is `/etc/confd`. Create the confdir by executing the following command:
+
+```Bash
+sudo mkdir -p /etc/confd/{conf.d,templates}
+```
+
+You don't have to use the default `confdir` location. For example you can create the confdir under your home directory. Then you tell confd to use the new `confdir` via the `-confdir` flag.
+
+```Bash
+mkdir -p ~/confd/{conf.d,templates}
+```
+
+### Create a template resource config
+
+Template resources are defined in [TOML](https://github.com/mojombo/toml) config files under the `confdir` conf.d directory (i.e. ~/confd/conf.d/*.toml).
+
+Create the following template resource config and save it as `~/confd/conf.d/myconfig.toml`.
+
+```Text
+[template]
+src = "myconfig.conf.tmpl"
+dest = "/tmp/myconfig.conf"
+keys = [
+  "/myapp/database/url",
+  "/myapp/database/user",
+]
+```
+
+### Create the source template
+
+Source templates are plain old [Golang text templates](http://golang.org/pkg/text/template/#pkg-overview), and are stored under the `confdir` templates directory. Create the following source template and save it as `~/confd/templates/myconfig.conf.tmpl`
+
+```
+# This a comment
+[myconfig]
+database_url = {{ .myapp_database_url }}
+database_user = {{ .myapp_database_user }}
+```
+
+### Processing template resources
+
+confd supports two modes of operation, daemon and onetime mode. In daemon mode, confd runs in the foreground processing template resources every 5 mins by default. For this tutorial we are going to use onetime mode.
+
+```
+confd -verbose -onetime -backend env -confdir ~/confd
+```
+Output:
+```
+2013-11-03T18:00:47-08:00 confd[21294]: NOTICE Starting confd
+2013-11-03T18:00:47-08:00 confd[21294]: NOTICE Backend set to env
+2013-11-03T18:00:47-08:00 confd[21294]: INFO Target config /tmp/myconfig.conf out of sync
+2013-11-03T18:00:47-08:00 confd[21294]: INFO Target config /tmp/myconfig.conf has been updated
+```
+
+The `dest` config should now be in sync with the template resource configuration.
+
+```
+cat /tmp/myconfig.conf
+```
+
+Output:
+```
+# This a comment
+[myconfig]
+database_url = db.example.com
+database_user = rob
+```