Add a version command.

The git tag/revision is saved when running "make install", and can be
displayed using "dokku version".

Makefile

@@ -2,19 +2,23 @@ SSHCOMMAND_URL ?= https://raw.github.com/progrium/sshcommand/master/sshcommand
 PLUGINHOOK_URL ?= https://s3.amazonaws.com/progrium-pluginhook/pluginhook_0.1.0_amd64.deb
 STACK_URL ?= github.com/progrium/buildstep
 PREBUILT_STACK_URL ?= https://s3.amazonaws.com/progrium-dokku/progrium_buildstep_79cf6805cf.tgz
+DOKKU_ROOT ?= /home/dokku
 
-.PHONY: all install copyfiles plugins dependencies sshcommand pluginhook docker aufs stack count
+.PHONY: all install copyfiles version plugins dependencies sshcommand pluginhook docker aufs stack count
 
 all:
 	# Type "make install" to install.
 
-install: dependencies stack copyfiles plugins
+install: dependencies stack copyfiles plugins version
 
 copyfiles:
 	cp dokku /usr/local/bin/dokku
 	mkdir -p /var/lib/dokku/plugins
 	cp -r plugins/* /var/lib/dokku/plugins
 
+version:
+	git describe --tags > ${DOKKU_ROOT}/VERSION
+
 plugins: pluginhook docker
 	dokku plugins-install
 

plugins/00_dokku-standard/commands

@@ -66,12 +66,20 @@ case "$1" in
     fi
     ;;
 
+  version)
+    cat "$DOKKU_ROOT/VERSION" || {
+      echo "Unable to determine dokku's version" 2>&1
+      exit 1
+    }
+    ;;
+
   help)
     cat && cat<<EOF
     delete <app>                                    Delete an application
     logs <app> [-t]                                 Show the last logs for an application (-t follows)
     run <app> <cmd>                                 Run a command in the environment of an application
     url <app>                                       Show the URL for an application
+    version                                         Print dokku's version
 EOF
     ;;