limit maximum length of environment keys generated by a logpipeline

[a-thaler]

Description
It turned out that with fluentbit 2.0 the maximum length of an environment key is limited. A key like ABC_APP_TEST_CLS_FLUENT_BIT_SECRET_FLUENTD_HTTP_HOST gets replaced proper when used in a a variable placeholder, but a key like ABC_APPLICATION_LOG_TEST_CLS_FLUENT_BIT_SECRET_FLUENTD_HTTP_HOST simply gets not resolved.

Even if the issue gets created and fixed, there might be a limit always and it should be assured that generated keys cannot grow indefinitely.

So please limit the max length of the generated keys.

Criterias

• environment variable keys which can be used in fluentbit placeholders have a maximum length
• the maximum is compatible with fluentbit 2
• upgrade to new logic will not break existing setups

[a-thaler]

The issue got fixed upstream and is already available with newest patch version 2.0.5. I verified it and it works as before. As the chance of running into further limits is very rare, I will close the issue as the priority gets very low.