Current state: Accepted
Discussion thread: here
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
So far it is not possible to inject additional configurations stored in environment variables. This topic came up in several projects and would be a useful feature to have as a Kafka config feature similar to file/directory providers, example configuration:
A new implementation of the interface org.apache.kafka.common.config.provider.ConfigProvider will be added.
The provider will expose a configuration to restrict the environment variables accessing by the provider.
Documentation: A pattern / regular expression that needs to match for environment variables to be used by this config provider
A class EnvVarConfigProvider implementing the ConfigProvider interface will be added. Core functionality is to provide the map returned by System.getEnv() via the get methods of the ConfigProvider.
Example implementation: https://github.com/Schm1tz1/kafka-config-provider-env-var was already added to https://github.com/Schm1tz1/kafka/tree/kip-887
Compatibility, Deprecation, and Migration Plan
No compatibility issues as this will add a new separate functionality and configuration options.
No breakages expected. Integration testing with a client (producer/consumer) along with unit testing should be sufficient.
No currently known alternatives with a provider. One existing workaround that some implementations use are templates for configs and scripts to replace environment variables.