fluent-bit: Deploy log collector for Victoria Logs

[fluent-bit][0] is a generic, highly-configurable log collector.  It was
apparently initially developed for fluentd, but is has so many output
capabilities that it works wil many different log aggregation systems,
including Victoria Logs.

Although Victoria Logs supports the Loki input format, and therefore
_Promtail_ would work, I want to try to avoid depending on third-party
repositories.  _fluent-bit_ is packaged by Fedora, so there shouldn't be
any dependency issues, etc.

[0]: https://fluentbit.io

roles/fluent-bit/defaults/main.yml

@@ -0,0 +1,34 @@
+fluent_bit_config:
+  service: '{{ fluent_bit_config_service }}'
+  pipeline: '{{ fluent_bit_pipeline }}'
+
+fluent_bit_config_service:
+  log_level: '{{ fluent_bit_log_level }}'
+
+fluent_bit_log_level: info
+
+fluent_bit_pipeline:
+  inputs: '{{ fluent_bit_inputs }}'
+  filters: '{{ fluent_bit_filters }}'
+  outputs: '{{ fluent_bit_outputs }}'
+
+fluent_bit_inputs: '{{ fluent_bit_default_inputs }}'
+
+fluent_bit_default_inputs:
+- '{{ fluent_bit_input_systemd }}'
+
+fluent_bit_input_systemd:
+  name: systemd
+  tag: host.*
+  db: /var/lib/fluent-bit/journal
+  lowercase: true
+  strip_underscores: true
+
+fluent_bit_filters: []
+
+fluent_bit_outputs:
+- '{{ fluent_bit_null_output }}'
+
+fluent_bit_null_output:
+  name: null
+  match: '*'