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Status
Current state: "Under Discussion"
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Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
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In managed Kafka service world, the service provider needs a way for billing the customer by the network usage inbound/outbound. To do that we have the following options:
- Counting the network usage via the metrics in other component, ex: proxy software like nginx, HAProxy. That works only for the connection from/to external endpoints. Besides, using the metrics in proxy software will have some over-counted number because not every network package entering Kafka in the end, ex: when an IP is rejected by the proxy software, or authentication failure... etc. But all the package flow will be counted into the metrics in proxy software.
Using the
BrokerTopicMetrics
in Kafka.Description Mbean name Normal value Byte in rate from clients kafka.server:type=BrokerTopicMetrics, name=BytesInPerSec,topic=([-.\w]+) Byte in (from the clients) rate per topic. Omitting 'topic=(...)' will yield the all-topic rate. Byte in rate from other brokers kafka.server:type=BrokerTopicMetrics, name=ReplicationBytesInPerSec,topic=([-.\w]+) Byte in (from the other brokers) rate per topic. Omitting 'topic=(...)' will yield the all-topic rate. Byte out rate to clients kafka.server:type=BrokerTopicMetrics, name=BytesOutPerSec,topic=([-.\w]+) Byte out (to the clients) rate per topic. Omitting 'topic=(...)' will yield the all-topic rate. Byte out rate to other brokers kafka.server:type=BrokerTopicMetrics, name=ReplicationBytesOutPerSec,topic=([-.\w]+) Byte out (to the other brokers) rate per topic. Omitting 'topic=(...)' will yield the all-topic rate. While this metrics can count bytes in (ex: client produce records) and bytes out (ex: consumer fetch records) to clients and to brokers in all topics, there are still some network packages are not included, ex: consumer heartbeat, producer send retry, authentication, authorization...etc.
- Kafka also exposed request size in bytes
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- per request type:
Description | Mbean name | Normal value |
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Request size in bytes | kafka.network:type=RequestMetrics,name=RequestBytes,request=([-.\w]+) | Size of requests for each request type. |
But However, the metrics is in "histogram" type, so it needs further process to sum all the data. Besides, it also expose request size, not response size. And grouping by request type is not helpful in our use case.
Therefore, we're going to expose metrics for bytes in/bytes out per listener. This can help precisely calculate the network usage externally or internally.
Public Interfaces
Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.
A public interface is any change to the following:
Binary log format
The network protocol and api behavior
Any class in the public packages under clientsConfiguration, especially client configuration
org/apache/kafka/common/serialization
org/apache/kafka/common
org/apache/kafka/common/errors
org/apache/kafka/clients/producer
org/apache/kafka/clients/consumer (eventually, once stable)
Monitoring
Command line tools and arguments
- Anything else that will likely break existing users in some way when they upgrade
Proposed Changes
Two new metrics will be added:
Description | Mbean name | Normal value |
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Byte in rate per listener. | kafka.network:type=RequestMetrics,name=BytesInPerSec,listener=([-.\w]+) | Byte in rate per listener. |
Byte out rate per listener. | kafka.network:type=ResponseMetrics,name=BytesOutPerSec,listener=([-.\w]+) | Byte out rate per listener. |
Proposed Changes
Two new metrics will be addedDescribe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.
Compatibility, Deprecation, and Migration Plan
- What impact (if any) will there be on existing users?
- If we are changing behavior how will we phase out the older behavior?
- If we need special migration tools, describe them here.
- When will we remove the existing behavior?
Test Plan
Describe in few sentences how the KIP will be tested. We are mostly interested in system tests (since unit-tests are specific to implementation details). How will we know that the implementation works as expected? How will we know nothing broke?
Rejected Alternatives
If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.