kafka cache_server

The kafka cache_server binding supports proactive fetch of messages to keep the cache fresh in preparation for new consumers. This is enabled by configuring a list of bootstrap topics for the binding.

kafka_cache_server:
  type: kafka
  kind: cache_server
  options:
    bootstrap:
      - items-responses
  exit: kafka_client

Configuration (* required)

options

object

The cache_server specific options.

options:
  bootstrap:
    - items-requests
    - items-responses
  topics:
    - name: items-requests
      defaultOffset: live

options.bootstrap

array of string

Topics to bootstrap in cache server even when no clients.

Kafka ACL Requirements

When using bootstrap, the Zilla service principal must have the following ACLs on each bootstrapped topic:

Operation	Resource Type	Description
DESCRIBE	Topic	Required to fetch topic metadata and partition information
READ	Topic	Required to fetch messages from the topic

options.topics

array of object

Topic configuration.

topics[].name

string

Topic name.

topics[].key

enum [ avro, double, float, int32, int64, json, protobuf, string ], object

Enforce validation for key

key.model*

enum [ avro, double, float, int32, int64, json, protobuf, string ]

A schema or type to validate the topic's key. Refer to the individual model docs for type specific implementation.

topics[].value

enum [ avro, double, float, int32, int64, json, protobuf, string ], object

Enforce validation for value

value.model*

enum [ avro, double, float, int32, int64, json, protobuf, string ]

A schema or type to validate the topic's value. Refer to the individual model docs for type specific implementation.

topics[].defaultOffset

enum [ live, historical ]

Fetch offset to use for new consumers

topics[].transforms

array

Extract key or value attributes from the typed Kafka message to apply to the Kafka message id or Kafka headers. The extract-key property must come before the extract-headers property if they both exist.

transforms:
  - extract-key: ${message.key.id}

transforms:
  - extract-headers:
      my-kafka-header: ${message.value.test}

transforms:
  - extract-key: ${message.value.id}
  - extract-headers:
      my-kafka-header: ${message.value.test}

transforms[].extract-key

string | Pattern: ^\\$\\{message\\.(key|value)\\.([A-Za-z_][A-Za-z0-9_]*)\\}$

Use a part of the Kafka message as the Kafka message key.

transforms[].extract-headers

object as map of named string properties | Pattern: ^\\$\\{message\\.(key|value)\\.([A-Za-z_][A-Za-z0-9_]*)\\}$

Use a part of the Kafka message as a Kafka message header.

routes*

array of object

Conditional kafka specific routes.

routes[].guarded

object as map of named array of string

List of roles required by each named guard to authorize this route.

routes:
  - guarded:
      my_guard:
        - read:items

routes[].when

array of object

List of conditions (any match) to match this route. Read more: When a route matches

when[].topic

string

Topic name pattern.

routes[].exit

string

Next binding when following this route.

exit: echo_server

exit

string

Default exit binding when no conditional routes are viable.

exit: echo_server

telemetry

object

Defines the desired telemetry for the binding.

telemetry.metrics

array

Telemetry metrics to track

telemetry:
  metrics:
    - stream.*