unifi: Configure Fluent Bit for Unifi server

The Unifi Network server writes a bunch of log files that we need to
forward to Victoria Logs.  This commit introduces components to the
Fluent Bit pipeline to read these files with the `tail` input plugin,
parse them using regular expressions to extract the correct time stamp
from the messages, and send them to Victoria Logs.

group_vars/unifi/fluent-bit.yml

@@ -0,0 +1,93 @@
+fluent_bit_multiline_parsers:
+- name: multiline_unifi
+  type: regex
+  flush_timeout: 500
+  rules:
+  - state: start_state
+    regex: ^\[\d{4}-\d{2}-\d{2}T.*
+    next_state: cont
+  - state: cont
+    regex: ^[^\[].*
+    next_state: cont
+- name: multiline_mongod
+  type: regex
+  flush_timeout: 500
+  rules:
+  - state: start_state
+    regex: ^\d{4}-\d{2}-\d{2}T.*
+    next_state: cont
+  - state: cont
+    regex: ^(?!\d{4}-\d{2}-\d{2}T).*
+    next_state: cont
+
+unifi_server_logs:
+- /var/log/unifi/migration.log
+- /var/log/unifi/server.log
+- /var/log/unifi/startup.log
+- /var/log/unifi/state.log
+- /var/log/unifi/tasks.log
+
+fluent_bit_input_unifi:
+  name: tail
+  alias: unifi.server
+  tag: unifi.server
+  path: '{{ unifi_server_logs | join(",") }}'
+  path_key: filename
+  multiline.parser: multiline_unifi
+  db: /var/lib/fluent-bit/unifi.db
+  read_from_head: true
+
+fluent_bit_input_unifi_mongod:
+  name: tail
+  alias: unifi.mongod
+  tag: unifi.mongod
+  path: /var/log/unifi/mongod.log
+  path_key: filename
+  multiline.parser: multiline_mongod
+  db: /var/lib/fluent-bit/unifi-mongod.db
+  read_from_head: true
+
+fluent_bit_unifi_inputs:
+- '{{ fluent_bit_input_unifi }}'
+- '{{ fluent_bit_input_unifi_mongod }}'
+
+fluent_bit_inputs: '{{ fluent_bit_default_inputs + fluent_bit_unifi_inputs }}'
+
+fluent_bit_parsers:
+- name: unifi-server
+  format: regex
+  regex: /^\[(?<timestamp>\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2},\d{3}([\+-]\d{4}|Z))\] (?<log>.*)/m
+  time_key: timestamp
+  time_format: '%Y-%m-%dT%H:%M:%S,%L%z'
+- name: mongod
+  format: regex
+  regex: /^(?<timestamp>\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.\d{3}[\+-]\d{4}) (?<log>.*)/m
+  time_key: timestamp
+  time_format: '%Y-%m-%dT%H:%M:%S.%L%z'
+
+fluent_bit_unifi_filters:
+- name: parser
+  alias: unifi-server
+  match: unifi.server
+  key_name: log
+  parser: unifi-server
+  reserve_data: true
+- name: parser
+  alias: unifi-mongod
+  match: unifi.mongod
+  key_name: log
+  parser: mongod
+  reserve_data: true
+
+fluent_bit_filters: '{{ fluent_bit_default_filters + fluent_bit_unifi_filters }}'
+
+fluent_bit_output_unifi:
+  name: http
+  alias: unifi
+  match: unifi.*
+  uri: /insert/jsonline?_stream_fields=hostname,filename&_msg_field=log&_time_field=date
+
+fluent_bit_unifi_outputs:
+- '{{ fluent_bit_output_unifi | combine(fluent_bit_output_template_victorialogs) }}'
+
+fluent_bit_outputs: '{{ fluent_bit_main_outputs + fluent_bit_unifi_outputs }}'