Otherwise, `postfix_up{path="/var/lib/postfix/queue/public/showq"}` will
always be `0` indicating an postfix outage because this is a unix domain
socket that cannot be connected to:
2021/12/03 14:50:46 Failed to scrape showq socket: dial unix /var/lib/postfix/queue/public/showq: socket: address family not supported by protocol
The option `services.prometheus.environmentFile` has been removed since it was causing [issues](https://github.com/NixOS/nixpkgs/issues/126083) and Prometheus now has native support for secret files.
The new option `services.prometheus.enableReload` has been introduced
which, when enabled, causes the prometheus systemd service to reload
when its config file changes.
More specifically the following property holds: switching to a
configuration (`switch-to-configuration`) that changes the prometheus
configuration only finishes successully when prometheus has finished
loading the new configuration.
`enableReload` is `false` by default in which case the old semantics
of restarting the prometheus systemd service are in effect.
9fea6d4c85 broke rtl_433-exporter by
introducing several hardening options which do not play well with
rtl_433 requiring writing to USB. More precisely, rtl_433 requires
(a) AF_NETLINK to configure the radio; (b) access to the USB device,
but PrivateDevices=true hides them; (c) rw access to the USB device,
but DeviceAllow= block-lists everything.
This commit was tested on real hardware with a standard NixOS setup.
The timex collector (enabled by default) needs the
adjtimex syscall, which was disabled by
9fea6d4c85.
So allow it unless the timex collector is disabled.
The systemd collector needs AF_UNIX to talk to
/var/run/dbus/system_bus_socket, which was broken
with 9fea6d4c85.
This commit allows AF_UNIX when needed.
In 0.3.0 of the json-exporter[1] it was switched to a different jsonpath
library which made some changes - especially for spaces in keys -
necessary. Also I decided to remove the pretty-printed JSON as this
would interfere with the bash quoting too much. If one needs
pretty-printed output, they can still pipe the output to `jq`.
[1] https://github.com/prometheus-community/json_exporter/releases/tag/v0.3.0
