Rackbox runit script for unicorn

sv-unicorn-run.erb

#!/bin/bash --login

#
# Supervises unicorn; stopping this service prompts a graceful shutdown of the
# current unicorn instance. Sending HUP to this service causes unicorn to re-exec
# itself for upgrades etc.
#

function is_pid_running() {
    set +e
    if [ -n $1 ] && kill -0 $1 >/dev/null 2>&1; then
        echo "yes"
    fi
    set -e
}

echo "My pid: $$"

APP_DIR=<%= @options[:working_directory] %>
CUR_PID_FILE=$APP_DIR/../shared/pids/unicorn.pid
OLD_PID_FILE=$CUR_PID_FILE.oldbin

if [ -e $OLD_PID_FILE ]; then
    OLD_PID=$(cat $OLD_PID_FILE)
    echo "Unicorn appears to be restarting: waiting for old master ($OLD_PID) to exit"
    while [ -n "$(is_pid_running $OLD_PID)" ]; do
        /bin/echo -n '.'
        sleep 2
    done
fi

if [ -e $CUR_PID_FILE ]; then
    CUR_PID=$(cat $CUR_PID_FILE)
    if [ -n "$(is_pid_running $CUR_PID)" ]; then
        echo "Already running as $CUR_PID"
        RUNNING=true
    fi
fi

if [ ! $RUNNING ]; then
    echo "Starting unicorn"
    exec 2>&1
    exec <%= File.join(@options[:working_directory], 'bin', (@options[:smells_like_rack] ? 'unicorn' : 'unicorn_rails')) %> -E <%= @options[:rack_env] %> -c <%= @options[:unicorn_config_file] %>
    sleep 2
    CUR_PID=$(cat $CUR_PID_FILE)
fi

function restart() {
    # TODO: regenerate config if this file has changed

    # Tell unicorn to re-exec itself
    echo "Asking unicorn to re-exec itself with USR2"
    kill -USR2 $CUR_PID
    # Wait and then exit -- after runit restarts the script, we'll
    # wait for the re-exec'd process
    sleep 2
    echo "Restarting to supervise new unicorn"
    exit
}

function graceful_shutdown() {
    echo "Requesting graceful shutdown"
    kill -QUIT $CUR_PID
}

trap restart HUP QUIT
trap graceful_shutdown INT TERM

echo "Watching for unicorn ($CUR_PID) exiting"
while [ -n "$(is_pid_running $CUR_PID)" ]; do
    /bin/echo -n '.'
    sleep 2
done
echo "Unicorn has exited."