How to support several nodejs services by upstart and monit?

Question

I have created an upstart script in order to daemonize a node.js app:

description "app_name"

start on startup
stop on shutdown

script
    export HOME="/home/ubuntu/nodeapp"

    exec sudo -u nodejs /usr/local/bin/node $HOME/app/server.js production 2>>/var/log/app_name.error.log >>/var/log/app_name.log
end script

My monit script is the following:

check host app_name with address 127.0.0.1
    start "/sbin/start app_name"
    stop "/sbin/stop app_name"
    if failed port 80 protocol HTTP
        request /ok
        with timeout 5 seconds
        then restart

It works fine, but now I want to add nginx as load balancer with upstream like the following:

upstream cluster1 {
  least_conn;
  server 127.0.0.1:8000;
  server 127.0.0.1:8001;
}

server {
    listen 0.0.0.0:80;

    location / {
    proxy_pass http://cluster1;
    }
}

So how should I change upstart and monit scripts to support that?

Answer 1

You should create three monit checks, one for nginx and one for each nodejs instance:

check host nginx with address 127.0.0.1
    start "/sbin/start nginx"
    stop "/sbin/stop nginx"
    if failed port 80 protocol HTTP
        request /ok
        with timeout 5 seconds
        then restart

check host app_name_on_8000 with address 127.0.0.1
    start "/sbin/start app_name_on_8000"
    stop "/sbin/stop app_name_on_8000"
    if failed port 8000 protocol HTTP
        request /ok
        with timeout 5 seconds
        then restart

check host app_name_on_8001 with address 127.0.0.1
    start "/sbin/start app_name_on_8001"
    stop "/sbin/stop app_name_on_8001"
    if failed port 8000 protocol HTTP
        request /ok
        with timeout 5 seconds
        then restart

That will restart nodejs instances when they fail, and nginx if fails or both nodejs instances are down