Bulk refactor `Gauge` metrics to be homeserver-scoped. We also add lints
to make sure that new `Gauge` metrics don't sneak in without using the
`server_name` label (`SERVER_NAME_LABEL`).
Part of https://github.com/element-hq/synapse/issues/18592
### Testing strategy
1. Add the `metrics` listener in your `homeserver.yaml`
```yaml
listeners:
# This is just showing how to configure metrics either way
#
# `http` `metrics` resource
- port: 9322
type: http
bind_addresses: ['127.0.0.1']
resources:
- names: [metrics]
compress: false
# `metrics` listener
- port: 9323
type: metrics
bind_addresses: ['127.0.0.1']
```
1. Start the homeserver: `poetry run synapse_homeserver --config-path
homeserver.yaml`
1. Fetch `http://localhost:9322/_synapse/metrics` and/or
`http://localhost:9323/metrics`
1. Observe response includes the TODO metrics with the `server_name`
label
### Pull Request Checklist
<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->
* [x] Pull request is based on the develop branch
* [x] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
- Use markdown where necessary, mostly for `code blocks`.
- End with either a period (.) or an exclamation mark (!).
- Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [x] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
(Applies to the Grafana graphs)
As discovered by @devonh, we use `synapse_storage_events_persisted_events_total` (which tracks *all* persisted events) for the "Events" rate in the "Event Send Time Quantiles" graph. This is pretty misleading as I would expect it to be the rate of events being sent given the graph title, "Event Send Time Quantiles".
Since the event persistence queues are shared for local and remote events from federation and will block local events being sent, I think it does still make sense to have the event persist rate. I've updated the graph to include the rate of "Local events being persisted" and the rate of "All events being persisted". I think this properly disambiguates and clarifies what the graph is trying to show.
Fix https://github.com/matrix-org/synapse/issues/15662
This manifests as purple lines that show up on all time series panels
that you can hover and see what version was deployed.
Also added a new "Deployed Synapse versions over time" panel
where the color block changes with each version. And mixed this
color block into the "Up" time series panel.
To get the Grafana dashboard JSON to copy here: use the **Share** icon at the top -> **Export** -> check the **Export for sharing externally** option -> **View JSON** or **Save to file**
