How many monitoring tools do you have?
Chances are at least 2-3. One tool usually does not cover all cases, and it’s usually a combination of self-managed and managed tools.
Self-managed gives you more control over custom configurations and cost. Managed ones take away the headache of running it yourself.
Prometheus is the de-facto standard for monitoring these days if you have a modern application stack and you want to manage your own
monitoring. It is metrics-based, i.e., it uses metrics as the source of data from all the monitored systems. There are
ready-made exporters for almost all popular infrastructure components.
You can send your application and business metrics to Prometheus too with
OpenTelemetry exporters.
This model does not work for all aspects of your service. E.g. If you want to monitor external properties like your website, or use synthetic
monitoring to check your customer-facing APIs from global locations, you could use something like Pingdom or UptimeRobot. This becomes another source of
data about your service's uptime.