Run nova components in a screen

nova-screen.sh

#!/bin/bash

# This script runs all nova components in windows of a singe screen.
# Arguments: [nova.conf] [novarc]

function locate_binary {
	# Called with the basename of a binary, like nova-api
	# If we are in a nova checkout, use the bin/* version.
	# Otherwise, get whatever is in ${PATH} for system wide nova
	bin_name=${1}
	var_name=`echo ${bin_name} | sed -e s.-._.`
	if [ -d bin ] && [ -f bin/${bin_name} ] ; then
		eval ${var_name}="bin/${bin_name}"
	else
		rv=`which ${bin_name}`
		if [ -z "${rv}" ] ; then
			echo "FATAL: Unable to find a suitable ${bin_name}"
			echo "    Either use ${BASH_SOURCE} from a bzr checkout of nova"
			echo "    or put ${bin_name} in your \$PATH"
			exit 1
		fi
		eval ${var_name}="${rv}"
	fi
}

function screen_is_running {
	# Check for a running screen session
	# You can specify a session name other than nova by providing an argument
	# Returns 0 if running, 1 otherwise
	# Can be used in bash conditionals
	session_name=${1}
	if [ -z "${session_name}" ] ; then
		session_name=nova
	fi
	captured=`screen -ls | grep ${session_name}`
	if [ -z "${captured}" ] ; then
		return 1 # not running
	fi
	return 0
}

function start_screen {
	# Starts a new screen session
	# You can specify a session name other than nova by providing an argument
	session_name=${1}
	if [ -z "${session_name}" ] ; then
		session_name=nova
	fi
	screen_is_running ${session_name}
	if [ $? == 0 ] ; then
		echo "FATAL: screen session ${session_name} already exists"
		exit 1
	fi
	# -d -m creates a new detached session per screen(1)
	# -S names the session which we will use to attach to later
	# -t names the particular window in screen we can attach to later
	screen -d -m -S ${session_name} -t default
}

function add_to_screen {
	# Add a command to a new window in an existing screen session
	# Arguments: session-name command
	session_name=${1}
	command=${2}
	if [ -z "${command}" ] ; then
		echo "INVALID USAGE: add_to_screen session-name command"
		return
	fi
	screen_is_running ${session_name}
	if [ $? == 1 ] ; then
		echo "ERROR: No running screen session named ${session_name}"
		echo "    Skipping command ${command}"
		return
	fi
	basename=`echo ${command} | awk '{print $1}' | xargs basename`
	# -X screen_command sends a screen internal command
	# (as would be produced by a keystroke, not a command like a shell command)
	# see screen(1) sections DEFAULT KEY BINDINGS and CUSTOMIZATION
	# 'screen' is equivilent to C-a C-c, which creates a new window
	screen -S ${session_name} -X screen -t ${basename}
	# ASCII Carriage Return to emulate pressing enter.
	CR=`echo -ne '\r'`
	# -p selects a window by name (paired with -t in screen command above)
	# the stuff command puts the text in screen's input buffer
	# this throws the command, followed by enter, to the shell running in screen
	screen -S ${session_name} -p ${basename} -X stuff "${command}${CR}"
}

function build_screen_keymap {
	# Map F1 key to windowlist
	# You can specify a session name other than nova by providing an argument
	session_name=${1}
	if [ -z "${session_name}" ] ; then
		session_name=nova
	fi
	screen_is_running ${session_name}
	if [ $? == 1 ] ; then
		echo "ERROR: No running screen session named ${session_name}"

		echo "    Skipping command ${command}"
		return
	fi
	basename=`echo ${command} | awk '{print $1}' | xargs basename`
	# -X screen_command sends a screen internal command
	# (as would be produced by a keystroke, not a command like a shell command)
	# see screen(1) sections DEFAULT KEY BINDINGS and CUSTOMIZATION
	# 'screen' is equivilent to C-a C-c, which creates a new window
	screen -S ${session_name} -X screen -t ${basename}
	# ASCII Carriage Return to emulate pressing enter.
	CR=`echo -ne '\r'`
	# -p selects a window by name (paired with -t in screen command above)
	# the stuff command puts the text in screen's input buffer
	# this throws the command, followed by enter, to the shell running in screen
	screen -S ${session_name} -p ${basename} -X stuff "${command}${CR}"
}

function build_screen_keymap {
	# Map F1 key to windowlist
	# You can specify a session name other than nova by providing an argument
	session_name=${1}
	if [ -z "${session_name}" ] ; then
		session_name=nova
	fi
	screen_is_running ${session_name}
	if [ $? == 1 ] ; then
		echo "ERROR: No running screen session named ${session_name}"
		echo "    Can't add key bindings"
		return
	fi
	screen -S ${session_name} -X bindkey -k k1 windowlist -b
}

function drop_from_screen {
	# Kill a window in a screen
	# Arguments: session_name window_name
	session_name=${1}
	window_name=${2}
	if [ -z "${window_name}" ] ; then
		echo "INVALID USAGE: drop_from_screen session-name window-name"
		return
	fi
	screen_is_running ${session_name}
	if [ $? == 1 ] ; then
		echo "ERROR: No running screen session named ${session_name}"
		echo "    Can't drop window ${window_name}"
		return
	fi
	screen -S ${session_name} -p ${window_name} -X kill
}

function attach_to_screen {
	# Attaches to a running but detached screen
	# You can specify a session name other than nova by providing an argument
	session_name=${1}
	if [ -z "${session_name}" ] ; then
		session_name=nova
	fi
	screen -S ${session_name} -r
}

function build_screen {
	# Launch all the components in a screen session and attach to it
	session_name=${1}
	if [ -z "${session_name}" ] ; then
		session_name=nova
	fi
	start_screen "${session_name}"
	add_to_screen "${session_name}" "${nova_api} --flagfile=${flagfile}"
	add_to_screen "${session_name}" "${nova_compute} --flagfile=${flagfile}"
	add_to_screen "${session_name}" "${nova_network} --flagfile=${flagfile}"
	add_to_screen "${session_name}" "${nova_volume} --flagfile=${flagfile}"
	add_to_screen "${session_name}" "${nova_objectstore} --flagfile=${flagfile}"
	add_to_screen "${session_name}" "${nova_scheduler} --flagfile=${flagfile}"
	add_to_screen "${session_name}" "source ${BASH_SOURCE}"
	drop_from_screen "${session_name}" default
	build_screen_keymap "${session_name}"
	attach_to_screen "${session_name}"
}

function determine_flagfile {
	# Try to find a flagfile to use.
	# Check the first argument for explictness.  Try some defaults othereise.
	flagfile=${1}
	if [ ! -z "${flagfile}" ] ; then
		if [ ! -f ${flagfile} ] ; then
			echo "WARNING: can't find flagfile: ${flagfile}"
		fi
		return
	fi
	# Try a local version
	if [ -f nova.conf ] ; then
		flagfile="nova.conf"
		return
	fi
	# Try another local version (compatible with nova.sh)
	if [ -f bin/nova.conf ] ; then
		flagfile="bin/nova.conf"
		return

	fi
	# Try the system version
	if [ -f /etc/nova/nova.conf ] ; then
		flagfile="/etc/nova/nova.conf"
		return
	fi
	echo "WARNING: no flagfile found, using built-in settings"
	flagfile=""
}

function display_welcome {
	clear
	echo Thanks for using nova!
	echo 
	echo Your services have been started, you can view their screens by using
	echo C-a \" \(Thats Control+a, then press \"\) to view a list of windows and
	echo select the one you want to see.  You can return here by selecting
	echo the window named \"source\".
	echo 
	echo You should now be able to use euca2ools \(euca-run-instances, etc\)
	echo to interact with your cloud.
	echo 
}

function source_nova_rc {
	# Load novarc, can be passed in as argument, found as novarc, or built new
	novarc=${1}
	if [ ! -z "${novarc}" ] ; then
		source ${novarc}
		return
	fi
	if [ -f novarc ] ; then
		source novarc
		return
	fi
	# already aliased
	${nova_manage} --flagfile=${flagfile} project zipfile admin admin /tmp/admin.zip
	unzip -d /tmp /tmp/admin.zip novarc
	source /tmp/novarc
	rm /tmp/admin.zip
	rm /tmp/novarc
}

# find binaries or die trying
# sets $nova_api, etc as variables
locate_binary nova-api
locate_binary nova-compute
locate_binary nova-network

locate_binary nova-volume
locate_binary nova-scheduler
locate_binary nova-objectstore
locate_binary nova-manage

determine_flagfile "${1}"

if [ $0 == ${BASH_SOURCE} ] ; then
	# run from command line, make the screen
	build_screen
	echo "Screen Detached"
	echo -ne '\a'
else
	# sourced by bash, load the window with help and a good environment
	alias nova-manage="${nova_manage} --flagfile=${flagfile}"
	PS1="[nova-screen]${PS1}"
	display_welcome
	source_nova_rc "${2}"
	${nova_manage} --flagfile=${flagfile} service enable `hostname` nova-compute
	${nova_manage} --flagfile=${flagfile} service enable `hostname` nova-network
	${nova_manage} --flagfile=${flagfile} service enable `hostname` nova-volume
fi