Normalize Kafka configuration units to bytes

[dorbae]

Normalize Kafka configuration units to bytes for message and request size parameters.

Description

Kafka configuration units related to size are in bytes. However, ByteSize supports various units. I believe it's better to normalize the unit to bytes to help reduce human errors.

For example, if max-message-bytes is set with an MB unit, the topic configuration could mistakenly interpret it as 3 bytes instead of 3 MB:

// application.conf
whisk {
  kafka {
     ...
     events {
                segment-bytes   =  536870912
                retention-bytes = 1073741824
                retention-ms    = 3600000
                max-message-bytes = 3 m
            }

Currently, several topics set max.message.bytes as ${whisk.activation.kafka.payload.max} + ${whisk.activation.kafka.serdes-overhead}. Fortunately, this ensures the unit remains in bytes when summing the two values.

Despite this, I believe normalizing the unit to bytes will help prevent unexpected bugs.

Related issue and scope

• [ ] I opened an issue to propose and discuss this change (#????)

My changes affect the following components

• [ ] API
• [ ] Controller
• [x] Message Bus (e.g., Kafka)
• [ ] Loadbalancer
• [ ] Scheduler
• [ ] Invoker
• [ ] Intrinsic actions (e.g., sequences, conductors)
• [ ] Data stores (e.g., CouchDB)
• [ ] Tests
• [ ] Deployment
• [ ] CLI
• [ ] General tooling
• [ ] Documentation

Types of changes

• [x] Bug fix (generally a non-breaking change which closes an issue).
• [ ] Enhancement or new feature (adds new functionality).
• [ ] Breaking change (a bug fix or enhancement which changes existing behavior).

Checklist:

• [x] I signed an Apache CLA.
• [x] I reviewed the style guides and followed the recommendations (Travis CI will check :).
• [ ] I added tests to cover my changes.
• [ ] My changes require further changes to the documentation.
• [ ] I updated the documentation where necessary.