partial_message mode KO with stdout but OK with stderr

[tophfr]

Describe the question/issue

I tried to run the multiline example from https://github.com/aws-samples/amazon-ecs-firelens-examples/tree/mainline/examples/fluent-bit/filter-multiline-partial-message-mode

It works fine for me, but in stdout the last part is not concatenated with the rest of the message.

I tested serveral file contents with different sizes, I always get 2 log entries. The second one with the last splitted part of the content.

But with stderr, everything is OK : I get only one entry with the entire content.

Configuration

https://github.com/aws-samples/amazon-ecs-firelens-examples/blob/mainline/examples/fluent-bit/filter-multiline-partial-message-mode/custom-fluent-bit-with-config/extra.conf

Fluent Bit Version Info

public.ecr.aws/aws-observability/aws-for-fluent-bit:2.32.2.20240724 (=stable)

Cluster Details

ECS on EC2