We scaled up our resources to have our server run 3 instances. Previously we had a script that would run when the app starts up - it worked okay for 1 instance but is now running 3 times (one on each service). Ideally we only run the script once after a deploy (it’s mostly idempotent but does have some interesting race conditions if run multiple times concurrently).
Couple things we were considering:
Using a post deploy webhook where render tells us it is done deploying, then we run the script. Last I checked, this was not available yet
Use some crude numbering system environment variable where we could denote that only a specific index or instance should run the script on startup. To do this, we would need an environment variable set per instance (we were thinking of a simple 0, 1, 2 index)
Are either of these possible? If not, do you have any other suggestions to handle the horizontal nature of multiple instances. We’re looking for a quick solution to this while we work on a more scalable solution that doesn’t involve running this script on app startup
We don’t have a post-deploy hook or environment variable indexes as of today. I’ll investigate some potential workarounds for you. But first to start with a potentially naive question: Is this something that can be done during the build process rather than the deploy process? That would ensure it’s only run once per deployment.
I think we tried something with this a while back but there were issues with needing to expose a bunch of the environment variables in our docker build process…this was a while back now so might be worth another look.
We can take a look to see if this is possible - let us know if you think of anything on the render side that could help with this. This isn’t super high priority for us, just something I wanted to ask if there was any other workaround that could fix the issue for us. Thanks for the help!
@jake are there any workarounds that you’ve identified for this? I’d find this feature valuable too. In my case for scaling WordPress and disabling wordpress cronjob for all but one instance.