Add buffer_limit_size and buffer_overflow_method

[okkez]

Adds a size limit for concatenation.
If a concatenated record will overflow, the concatenate behavior will follow the `buffer_overflow_method'.

By default, it will continue to behave as before.

[cristianpetrula]

Any updates for this feature?

[emil2k]

@okkez Would it be possible to merge and release this feature? This is useful to us to avoid event too large errors when flushing to CloudWatch.

[okkez]

@kenhys Can you take a look?

[whitepiratebaku]

Hello, it would be nice to have this feature released. Basicly we use concat plugin to concatenate containerd logs with partial_key/partial_value but what happens sometimes we may get very large logs which can trigger BufferChunkOverflowError error and lead to OOM/crash of fluentd. @okkez do you happen to know any workaround for now? to avoid large log lines hit fluentd output plugin/buffer so we avoid BufferChunkOverflowError

[Watson1978]

@okkez Can you please fix the conflict?

[daipom]

I will try.

[Watson1978]

I solved the confilict and fixed up the commits.
And I backed up the original PR in Watson1978#1

[Watson1978]

LGTM. Thanks

[daipom]

Thanks @Watson1978!