add possibility for addtional config parameter

[zychonatic]

Is your feature request related to a problem? Please describe.

for elasticsearch output i would need to add a "pipeline" parameter to the config.
this is currently not possible, i guess it's because the pipeline parameter doesn't have a default

Describe the solution you'd like

my idea would be to include into the fluentd.conf file under

<match **>
   @type elasticsearch
   ....
an
  @include ./extra_params.conf 

line. with this we could add an additional configmap with all parameters we need, without extracting the whole config into a config map. This would be similar to the "tail_container_parse.conf" which is already included.

Describe alternatives you've considered

alternative only option would be to extract the whole fluentd.conf into a configmap and mount it back, which could break future updates.

Additional context

No response

[Watson1978]

Can you let us your use case?

[zychonatic]

we have logs coming from kubernetes pods in various forms. some are stdout in json format, others are via file, also in json. currently we are putting them all into the standard "logstash" index in elasticsearch, but for some lines (not complete files) we want to put them additionally into a separate index for longer storage time. for this i would like to use the ingest pipeline feature of elasticsearch. but currently i cannot add the config here without extracting the whole config and add one line. i thought with my idea, that we make it more modular, so that i can add such config parameter without extraction the whole config. this would make it much easier also for upgrades. the same concept is already done with the "tail_container_parse" config, and i thought it might be a good idea.

any thoughts from your side