I have a sailsjs app running in cluster mode with pm2 and two instances. One of the main reasons for wanting the two instances was so I could restart/update the app without having to bring the entire app down.
However, in the middle of a restart of one instance pm2 restart 4, the site is all wonky (that's the technical term) if I refresh it. I'm assuming this is because grunt is doing it's thing and the .tmp folder gets destroyed for both instances?
Is the only real approach with sailsjs to have two complete instances running on different ports and use something like nginx as the load balancer, or am I missing something with PM2 that would allow for staged restarts without any downtime or hiccups in the resources being available?
There are a few issues here.
You need to provide what versions of sails.js/node.js/pm2 you're running. In short, describe your environment as completely as possible.
Describing your issue more completely helps people write more concise and clear answers.
node.js cluster mode may change (as of v0.12.4) and is still considered "Unstable": https://nodejs.org/api/cluster.html#cluster_cluster
In the following thread, "mikermcneil commented on Dec 3, 2014" says to disable Grunt for production with pm2: https://github.com/balderdashy/sails/pull/1716
Let me clarify by saying I've used pm2 until just recently. In addition to Grunt, it has issues with socket connections while nginx handles it just fine. Trust me, chasing down that bug was not fun. Here's a link to the thread: https://github.com/Unitech/PM2/issues/389
As an alternate solution I chose to use nginx with parallel sails.js apps, using redis for sockets and sessions. Use forever to keep the apps running and disable grunt. Point nginx to the assets folder to serve static files quickly, bypassing sails.js and add caching to those assets.
Hope this helps!