Grafana: Payment dashboard: Revert "Redemption" back to old-style Graph panel

See merge request !270

nixpkgs update 2022-02-28

See merge request !275

The newer "Time Series" panel does not support two axes.

Grid configs: clean up config imports

See merge request !269

Grafana: Revamp network errors panel, add (experimental) PSI panels

See merge request !268

Miscellaneous changes

See merge request !262

... and fix that option the other commit introduced

Nix sometimes seems peculiar about merging sets?

define groups for tahoe nodes

See merge request !265

- Also alert on "negative" (== receiving) errors
- Use 'rate' so we can get out of the reporting if situation normalizes

Don't display the port number in Grafana dash tooltips

See merge request !267

If I understand the behavior current Prometheus and Grafana
correctly, this should remove the port number from the
paymentserver labels in Prometheus TDSB.

nixpkgs update 2022-02-21

See merge request !266

Grafana 8: Migrate Dashboards from Graph to TimeSeries panels

See merge request !263

groups based on cfg.introducers are already set up above and this expression
is clearly meant to define groups for the nodes

Grafana 8 recommends these for added performance and capabilities.

Specify ssh-keys as list of strings, rather than having a single string.

See merge request !254

Grafana: Payments dashboard log fix & fine tune

See merge request !260

- (tryfix) Switch to Loki datasource;
- Filter requests to metrics instead of all GET;
- Show the last week by default
- Show log times

Interesting and not quickly fixable as it looks like: the
GET ... line comes *after*  the result.  We might be logging
this wrong to begin with, but probably this is some next
gen AI line ordering intelligence

Update nixpkgs.

See merge request !259

Add a derivation that builds all three grids.

See merge request !253

Loki/Promtail: Towards centralized logging

Closes privatestorageops#207 and privatestorageops#389

See merge request !251

Or rather, let it listen only on localhost.
I thought Grafana needed it, or Promtail needed it, but I don't remember
clearly, the web doesn't say clearly, and on my local dev stack
Promtail/Loki seems to still work just fine without GRPC on the network.

OMG look at teh genius of it

Do some name resolution for those poor computers

Improve factoring by removing those `/etc/hosts` entries

And avoid the infinite loop @tomprince was encountering in !258