ref
https://linear.app/ghost/issue/ENG-1592/start-monitoring-connection-pool-utilization-in-ghost
- This commit adds prometheus metrics to the connection pool so we can
start to track connection pool utilization, number of pending acquires,
and also adds some basic SQL query summary metrics like queries per
minute and query duration percentiles.
- The connection pool has now been theorized to be a main constraint of
Ghost for some time, but it's been challenging to get actual visibility
into the state of the connection pool. With this change, we should be
able to directly observe, monitor and alert on the connection pool.
- Updated grafana version to fix a bug in the query editor that was
fixed in 8.3, even though this is a couple versions ahead of production
ref
https://linear.app/ghost/issue/ENG-1746/enable-ghost-to-push-metrics-to-a-pushgateway
- Trying to get Ghost working with the prometheus pushgateway in
staging, but it's logging an error each time it tries to push the
metrics. The error output is pretty useless for debugging, so this
commit improves the error messages to make it easier to debug.
ref
https://linear.app/ghost/issue/ENG-1746/enable-ghost-to-push-metrics-to-a-pushgateway
- We'd like to use prometheus to expose metrics from Ghost, but the
"standard" approach of having prometheus scrape the `/metrics` endpoint
adds some complexity and additional challenges on Pro.
- A suggested simpler alternative is to use a pushgateway, to have Ghost
_push_ metrics to prometheus, rather than have prometheus scrape the
running instances.
- This PR introduces this functionality behind a configuration.
- It also includes a refactor to the current metrics-server
implementation so all the related code for prometheus is colocated, and
the configuration is a bit more organized. `@tryghost/metrics-server`
has been renamed to `@tryghost/prometheus-metrics`, and it now includes
the metrics server and prometheus-client code itself (including the
pushgateway code)
- To enable the prometheus client alone, `prometheus:enabled` must be
true. This will _not_ enable the metrics server or the pushgateway — it
will essentially collect the metrics, but not do anything with them.
- To enable the metrics server, set `prometheus:metrics_server:enabled`
to true. You can also configure the host and port that the metrics
server should export the `/metrics` endpoint on in the
`prometheus:metrics_server` block.
- To enable the pushgateway, set `prometheus:pushgateway:enabled` to
true. You can also configure the pushgateway's `url`, the `interval` it
should push metrics in (in milliseconds) and the `jobName` in the
`prometheus:pushgateway` block.
