For security reasons, and generally, it is best to create a more fine
grained group than plugdev. This way users that wish to tweak razer
devices don't have access to the entire plugdev group's permissions.
This is of course a breaking change.
Nullmailer expects that this directory exists (see
073f4e9c5d/doc/nullmailer-send.8 (L185)).
When it doesn't and an email cannot be sent due to a permanent failure
or has been in the queue longer than queuelifetime (7 days), message
"Can't rename file: No such file or directory" starts appearing in the
log and nullmailer never sends "Could not send message" notification.
This means that the user may never learn that his email was not
delivered.
This fixes:
```
systemd[1]: Started VictoriaMetrics time series database.
victoria-metrics[379550]: 2021-08-04T19:33:39.833Z panic VictoriaMetrics/lib/storage/partition.go:954 FATAL: unrecoverable error when merging small parts in the partition "/var/lib/victoriametrics/data/small/2021_08": cannot open source part for merging: cannot open metaindex file in stream mode: cannot open file "/var/lib/victoriametrics/data/small/2021_08/1228_1228_20210804184120.712_20210804184121.899_16982E83CD7A763A/metaindex.bin": open /var/lib/victoriametrics/data/small/2021_08/1228_1228_20210804184120.712_20210804184121.899_16982E83CD7A763A/metaindex.bin: too many open files
victoria-metrics[379550]: panic: FATAL: unrecoverable error when merging small parts in the partition "/var/lib/victoriametrics/data/small/2021_08": cannot open source part for merging: cannot open metaindex file in stream mode: cannot open file "/var/lib/victoriametrics/data/small/2021_08/1228_1228_20210804184120.712_20210804184121.899_16982E83CD7A763A/metaindex.bin": open /var/lib/victoriametrics/data/small/2021_08/1228_1228_20210804184120.712_20210804184121.899_16982E83CD7A763A/metaindex.bin: too many open files
victoria-metrics[379550]: goroutine 629 [running]:
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger.logMessage(0xbb3ea1, 0x5, 0xc001113800, 0x1e7, 0x4)
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger/logger.go:270 +0xc69
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger.logLevelSkipframes(0x1, 0xbb3ea1, 0x5, 0xbe3f8b, 0x4b, 0xc000bb3f88, 0x2, 0x2)
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger/logger.go:138 +0xd1
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger.logLevel(...)
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger/logger.go:130
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger.Panicf(...)
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/logger/logger.go:126
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/storage.(*partition).smallPartsMerger(0xc0014d7980)
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/storage/partition.go:954 +0x145
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/storage.(*partition).startMergeWorkers.func1(0xc0014d7980)
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/storage/partition.go:933 +0x2b
victoria-metrics[379550]: created by github.com/VictoriaMetrics/VictoriaMetrics/lib/storage.(*partition).startMergeWorkers
victoria-metrics[379550]: github.com/VictoriaMetrics/VictoriaMetrics/lib/storage/partition.go:932 +0x6c
systemd[1]: victoriametrics.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
systemd[1]: victoriametrics.service: Failed with result 'exit-code'.
systemd[1]: victoriametrics.service: Consumed 587ms CPU time, received 6.5K IP traffic, sent 1.7K IP traffic.
systemd[1]: victoriametrics.service: Scheduled restart job, restart counter is at 2064.
systemd[1]: Stopped VictoriaMetrics time series database.
systemd[1]: victoriametrics.service: Consumed 587ms CPU time, received 6.5K IP traffic, sent 1.7K IP traffic.
systemd[1]: Starting VictoriaMetrics time series database...
```
This option allows basic configuration of the compression technique
used in the backup script. Specifically it adds `none` and `zstd` as
new alternatives, keeping `gzip` as the default.
The service likes to write files uploaded by the user to the service
user's $HOME. In our case the hqplayerd user has no home directory,
since it's a system user, and regardless we'd like to keep the service's
state contained.
With this change the unit forces HOME to point to
/var/lib/hqplayer/home, which works around the issue.
