I was looking to ask questions like:
- Number of requests per minute/hour/day - Number of celery workers working - Size of celery queue - Keys in redis - postgres stats - etc.
Basically what a macro-view of what is going on. I dont want to build my solution from scratch because I do not have the time.
Looks like you're looking mostly for the latter, in which case Prometheus + Grafana would be the free-to-play option I'd reach for first. The new Grafana Alerts looks interesting for covering the "alerting" piece. Cloudwatch is the logical choice for AWS stuff and it does both pretty well (although I don't know whether you need a separate service like PagerDuty to really handle alerts), but it's not free (especially as you do more with it), and some of the other options like a managed provider (Datadog, e.g.) become more attractive as you put more and more money into it.
Datadog is also pretty good at this but can cost quite a lot.