Ask HN: Recommendations for telemetry with low memory footprint

I am writing a free web service for a hobby community of mine. Since I expect to make negative revenue from it, I am hosting it on low tiers of providers that usually limit to 512 MB RAM.

I have tried Datadog, but their agent seems to consume up to 150 MB of memory, which is far too high to be comfortable for my use case (my application uses around 300 MB memory right now, which could go up as more traffic comes in).

I am considering just writing my own custom metric collector and dashboard, but I thought should ask for recommendations first.