# Background
Erigon currently uses a combination of Victoria Metrics and Prometheus
client for providing metrics.
We want to rationalize this and use only the Prometheus client library,
but we want to maintain the simplified Victoria Metrics methods for
constructing metrics.
This task is currently partly complete and needs to be finished to a
stage where we can remove the Victoria Metrics module from the Erigon
code base.
# Summary of changes
- Remove `UsePrometheusClient` boolean flag
- Remove `VictoriaMetrics` client lib and related code (simplifies
registry and prometheus http handler initialisation since now we have
only 1 registry and can use default `promhttp.Handler`)
# Background
Erigon currently uses a combination of Victoria Metrics and Prometheus
client for providing metrics.
We want to rationalize this and use only the Prometheus client library,
but we want to maintain the simplified Victoria Metrics methods for
constructing metrics.
This task is currently partly complete and needs to be finished to a
stage where we can remove the Victoria Metrics module from the Erigon
code base.
# Summary of changes
- Adds missing `NewCounter`, `NewSummary`, `NewHistogram`,
`GetOrCreateHistogram` functions to `erigon-lib/metrics` similar to the
interface VictoriaMetrics lib provides
- Minor tidy up for consistency inside `erigon-lib/metrics/set.go`
around return types (panic vs err consistency for funcs inside the
file), error messages, comments
- Replace all remaining usages of `github.com/VictoriaMetrics/metrics`
with `github.com/ledgerwatch/erigon-lib/metrics` - seamless (only import
changes) since interfaces match
# Background
Erigon currently uses a combination of Victoria Metrics and Prometheus
client for providing metrics.
We want to rationalize this and use only the Prometheus client library,
but we want to maintain the simplified Victoria Metrics methods for
constructing metrics.
This task is currently partly complete and needs to be finished to a
stage where we can remove the Victoria Metrics module from the Erigon
code base.
## Tests
### Functional
* Make sure that the format change int->float implied by VM to
Prometheus does not impact clients (pay particular attention to block
numbers)
* Check that the prometheus/grafana dashboards defined in cmd/prometheus
are functional after the change
(see docker-compose.yml for details and
https://github.com/ledgerwatch/erigon/tree/devel/cmd/prometheus#readme)
* Confirm that the underlying go metrics are still generated
* Confirm the following flags setting work:
--metrics, --metrics.addr, --metrics.port with the new code
* Confirm that --metrics and --proff settings and handlers configuration
still allow metrics and pprof to share a port
#### Float counters - scientific notation test case
#### Float counters - NaN test case
### Performance
* Check the performance of counters created by RPC calls measurements
created by rpc/metrics.go are not impacted by the change.
#### RPC
Performed tests on rpcdaemon & erigon on localhost using
`etc_blockNumber`.
Did tests with 100, 1000, 10000 requests. Got a steady 15 ms response
time.
#### Memory
Calling vm to get a metric and then preregistering it to avoid
duplication is expensive.
To avoid this we can make a local lookup first which is a map this
quicker. This is a temporary fix
until vm is removed at which point we'll have a single prom_client
registry
Fixes: https://github.com/ledgerwatch/erigon/issues/8558
