[stable/fluent-bit] Add Logstash_Prefix_Key as an optional parameter (#20719)

Signed-off-by: Chris Minton <christopher.minton@sainsburys.co.uk>

stable/fluent-bit/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: fluent-bit
-version: 2.8.9
+version: 2.8.10
 appVersion: 1.3.7
 description: Fast and Lightweight Log/Data Forwarder for Linux, BSD and OSX
 keywords:

stable/fluent-bit/README.md

@@ -46,7 +46,8 @@ The following table lists the configurable parameters of the Fluent-Bit chart an
 | `backend.es.retry_limit`   | Max number of retries to attempt (False == no limit) | `False` |
 | `backend.es.time_key`          | Elastic Time Key | `@timestamp` |
 | `backend.es.logstash_format`          | Enable Logstash format compatibility. | `On` |
-| `backend.es.logstash_prefix`  | Index Prefix. If Logstash_Prefix is equals to 'mydata' your index will become 'mydata-YYYY.MM.DD'. | `kubernetes_cluster` |
+| `backend.es.logstash_prefix`  | Index Prefix. If Logstash_Prefix is equal to 'mydata' your index will become 'mydata-YYYY.MM.DD'. | `kubernetes_cluster` |
+| `backend.es.logstash_prefix_key`  | Index Prefix key. When included, the value in the record that belongs to the key will be looked up and overwrite `Logstash_Prefix` for index generation. If `Logstash_Prefix_Key` = 'mydata' the index becomes 'mydata-YYYY.MM.DD'. | `` |
 | `backend.es.replace_dots`     | Enable/Disable Replace_Dots option. | `On` |
 | `backend.es.http_user`        | Optional username credential for Elastic X-Pack access. | `` |
 | `backend.es.http_passwd`      | Password for user defined in HTTP_User. | `` |

stable/fluent-bit/templates/config.yaml

@@ -138,6 +138,9 @@ data:
 {{- end }}
 {{- if .Values.backend.es.logstash_prefix }}
         Logstash_Prefix {{ .Values.backend.es.logstash_prefix }}
+{{- if .Values.backend.es.logstash_prefix_key }}
+        Logstash_Prefix_Key {{ .Values.backend.es.logstash_prefix_key }}
+{{- end }}
 {{ else if .Values.backend.es.index }}
         Index {{ .Values.backend.es.index }}
 {{- end }}