feat: add Knative Kafka Broker and Trigger support

[enchantednatures]

Summary

• Add Knative Kafka Broker + Triggers as an eventing path alongside existing KafkaSource, enabling the Knative eventing bus with Kafka as the interchange
• When kafka.broker.enabled: true, KafkaSources sink to the Broker and Triggers route events to services; when disabled, existing KafkaSource → Service behavior is preserved
• Bump ksvc library chart version 0.6.0 → 0.7.0

What Changed

New Templates

• _kafka-broker.tpl — Renders Broker CRD (eventing.knative.dev/v1 with Kafka class annotation) + ConfigMap (bootstrap servers, topic partitions/replication, auth secret, extras)
• _kafka-trigger.tpl — Renders Trigger CRDs with full semantics: legacy filter (CloudEvents attribute matching), modern filters (exact/prefix/suffix/all/any/not/cesql), per-trigger delivery (retry/backoff), DLQ Knative Services, custom annotations (e.g. kafka.eventing.knative.dev/delivery.order: ordered)

Modified Templates

• _kafka-source.tpl — Conditional sink: Broker ref when broker enabled, Knative Service ref when not
• _generate.tpl — Broker/trigger defaults in applyDefaults, rendering sections for Broker+ConfigMap and Trigger loop
• _validators.tpl — source.sink only required when broker disabled; triggers require broker enabled; trigger subscriber must reference valid services key
• _names.tpl — 4 new naming helpers: kafkaBrokerName, kafkaBrokerConfigName, kafkaTriggerName, kafkaTriggerDlqName

Tests & Examples

• 14 broker tests, 13 trigger tests, 2 broker-sink source tests (104 total, all passing)
• New examples/kafka-broker/ with multi-service + broker + 3 trigger patterns (unfiltered, legacy filter, modern filters with delivery ordering)

CI

• Integration test matrix: added kafka-broker example with Knative Eventing CRD install step
• Kubeconform skip list: added Broker,Trigger

Documentation

• README updated: architecture diagram, naming conventions, resources rendered table, full values reference for Broker and Triggers sections, kafka-broker example listing

Values Schema

kafka:
  broker:
    enabled: true
    config:
      bootstrapServers: ["kafka.kafka.svc.cluster.local:9092"]
      topicPartitions: 10
      topicReplicationFactor: 3
  triggers:
    order-events:
      subscriber: order-processor   # references services map key
      filter:
        type: com.example.order.created
      delivery:
        retry: 10

[Copilot]

Pull request overview

Adds Knative Eventing Kafka Broker + Trigger support to the ksvc Helm library chart as an alternative eventing path alongside the existing per-topic KafkaSource → Service pattern, and bumps the chart version to 0.7.0 with updated examples/CI/tests.

Changes:

• Introduces new Broker/Trigger Helm templates and naming helpers, plus render-time validations and values schema updates.
• Updates KafkaSource rendering to conditionally sink to the Broker when kafka.broker.enabled: true.
• Adds a new kafka-broker example, expands chart unit tests, and updates CI workflows to account for Broker/Trigger CRDs.

Reviewed changes

Copilot reviewed 18 out of 26 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
examples/postgres-only/Chart.lock	Bumps example dependency lock to ksvc 0.7.0.
examples/minimal/Chart.lock	Bumps example dependency lock to ksvc 0.7.0.
examples/kafka-consumer/Chart.lock	Bumps example dependency lock to ksvc 0.7.0.
examples/kafka-broker/values.yaml	Adds values demonstrating Broker + multiple Triggers + delivery/DLQ options.
examples/kafka-broker/templates/common.yaml	Wires the example to the library chart generator.
examples/kafka-broker/Chart.yaml	Adds the new kafka-broker example chart definition.
examples/kafka-broker/Chart.lock	Locks the new example chart dependency to ksvc 0.7.0.
examples/full-stack/Chart.lock	Bumps example dependency lock to ksvc 0.7.0.
examples/dragonfly-cache/Chart.lock	Bumps example dependency lock to ksvc 0.7.0.
charts/library/ksvc/values.schema.json	Extends values schema for kafka.broker and kafka.triggers; relaxes KafkaSource sink requirement.
charts/library/ksvc/test-chart/tests/kafka-trigger_test.yaml	Adds unit tests covering Trigger rendering, filters, delivery, and DLQ behavior.
charts/library/ksvc/test-chart/tests/kafka-source_test.yaml	Adds unit tests for KafkaSource sink behavior with/without broker enabled.
charts/library/ksvc/test-chart/tests/kafka-broker_test.yaml	Adds unit tests covering Broker + ConfigMap rendering and delivery/DLQ fields.
charts/library/ksvc/test-chart/Chart.lock	Bumps test chart lock to ksvc 0.7.0.
charts/library/ksvc/templates/loader/_generate.tpl	Renders Broker/ConfigMap and Trigger loop; applies defaults for broker/triggers.
charts/library/ksvc/templates/lib/_validators.tpl	Adjusts sink validation for broker mode; adds trigger validation requiring broker enabled.
charts/library/ksvc/templates/lib/_names.tpl	Adds naming helpers for broker/config/trigger/DLQ resources.
charts/library/ksvc/templates/classes/_kafka-trigger.tpl	Adds Trigger + per-trigger DLQ Knative Service templates.
charts/library/ksvc/templates/classes/_kafka-source.tpl	Updates KafkaSource sink to reference Broker when enabled.
charts/library/ksvc/templates/classes/_kafka-broker.tpl	Adds Broker + ConfigMap templates for Kafka-backed eventing bus.
charts/library/ksvc/README.md	Documents new Broker/Trigger capabilities, naming, and expanded values reference.
charts/library/ksvc/Chart.yaml	Bumps library chart version to 0.7.0 and updates description.
charts/app/ksvc/Chart.yaml	Updates app chart dependency to ksvc 0.7.0.
.gitignore	Ignores app chart Chart.lock generation artifacts.
.github/workflows/lint-test.yaml	Updates kubeconform skip list to include Broker/Trigger.
.github/workflows/integration-test.yaml	Adds kafka-broker example to matrix and installs Knative Eventing CRDs for it.

Comments suppressed due to low confidence (1)

charts/library/ksvc/values.schema.json:542

• values.schema.json no longer requires kafka.sources.<key>.sink, which is necessary when kafka.broker.enabled is false (the chart only fails later at template render time). Consider adding JSON Schema conditionals (if/then) so sink is required when the broker is disabled, and optional when enabled, to keep schema validation useful for consumers.

    "kafkaSourceEntry": {
      "type": "object",
      "additionalProperties": false,
      "required": ["topic"],
      "properties": {
        "topic": { "type": "string" },
        "consumerGroup": { "type": "string" },
        "bootstrapServers": {
          "type": "array",
          "minItems": 1,
          "items": { "type": "string" }
        },
        "consumers": { "type": "integer", "minimum": 1 },
        "initialOffset": {
          "type": "string",
          "enum": ["latest", "earliest"]
        },
        "sink": {
          "type": "string",
          "description": "Must reference a key in the services map"
        },
        "delivery": {

---

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[Copilot]

README default for kafka.sources.<key>.bootstrapServers is listed as [kafka.kafka.svc:9092], but the chart defaults in ksvc.loader.applyDefaults use kafka.kafka.svc.cluster.local:9092. Please align the documentation (or the default) so users get the correct value.

Suggested change

	| `kafka.sources.<key>.bootstrapServers` | List of bootstrap servers | `[kafka.kafka.svc:9092]` |
	| `kafka.sources.<key>.bootstrapServers` | List of bootstrap servers | `[kafka.kafka.svc.cluster.local:9092]` |

[Copilot]

README lists the defaults for kafka.broker.delivery.deadLetterSink.ref.apiVersion and .kind as empty strings, but ksvc.loader.applyDefaults sets them to serving.knative.dev/v1 and Service (and the template also defaults these fields). Update the defaults in the table to match the rendered behavior, or change the defaults to actually be empty.

Suggested change

	| `kafka.broker.delivery.deadLetterSink.ref.apiVersion` | DLQ ref apiVersion | `""` |
	| `kafka.broker.delivery.deadLetterSink.ref.kind` | DLQ ref kind | `""` |
	| `kafka.broker.delivery.deadLetterSink.ref.apiVersion` | DLQ ref apiVersion | `serving.knative.dev/v1` |
	| `kafka.broker.delivery.deadLetterSink.ref.kind` | DLQ ref kind | `Service` |