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Zilla Plus 2.x

Zilla Plus 2.x

Zilla Plus is Aklivity's enterprise product for deploying and operating production API and event streaming gateways. This page summarizes the notable additions, changes, and fixes in each 2.x release. It is not an exhaustive log of every merged pull request.

Note

Review the Breaking Changes below before upgrading from 1.x.

2.0.0

Release Date: September 7, 2026

Breaking Changes

See Migrating to 2.x for full details and config examples before upgrading.

  • The zilla.json config file fallback has been removed; a zilla.yaml file is now required.
  • binding-kafka: kind: client bindings can no longer route by topic condition; route unconditionally, or use cache_client/cache_server for per-topic dispatch.
  • binding-kafka: options.sasl has been removed in favor of options.authorization, which resolves credentials from a referenced guard instead of hardcoding them on the binding.
  • binding-grpc: options.services has been removed; .proto service definitions are now sourced from a catalog reference instead of local files.
  • binding-mqtt-kafka: options.server has been removed in favor of the engine-level service.hostname configuration property.
  • binding-mqtt: kind: server now requires a referenced options.store.
  • binding-tcp: routes[].exit is now actually enforced for kind: server.
  • binding-openapi / binding-asyncapi / binding-openapi-asyncapi: options.specs.<name>.servers is now a required list of plain URL strings instead of server objects.
  • binding-asyncapi / binding-openapi-asyncapi: route conditions api-id/operation-id are renamed to spec/operation, and kind: client bindings no longer accept routes.
  • binding-mcp: options and routes have been restructured — options.prompts is removed, options.authorization is now guard-name-keyed, capability route conditions are replaced by tool/prompt/resource, kind: server no longer accepts routes, and kind: client now requires options.server.
  • vault-aws-secrets: options.aliases has been removed; configure keys, trust, and signers directly as name-to-ARN maps.
  • guard-identity has been renamed to guard-inline.
  • guard-jwt: the guard-level kind property is no longer accepted.
  • The Kafka client and cache now target Apache Kafka 2.8.0 or higher.
  • binding-kafka-proxy's internal.authorization configuration has been restructured to a guard-name-keyed syntax, consistent with binding-kafka.
  • guard-api-keys now requires an explicit keys document structure in configuration instead of a hardcoded layout, and credentials() now returns the parsed secret instead of the identity.

Added

  • Model Context Protocol (MCP) support, letting AI agents discover and call Kafka, Kafka Connect, Schema Registry, OpenAPI, and HTTP backends as MCP tools:
    • binding-mcp-kafka: topic administration and metadata, cluster and broker overview, consumer group management (list, describe, reset offsets, lag), topic and broker configs, ACLs, and message produce/consume.
    • binding-mcp-kafka-connect: exposes the Kafka Connect REST API as MCP tools.
    • binding-mcp-schema-registry: exposes a Schema Registry as MCP tools, in client and proxy variants.
    • binding-mcp-openapi and binding-mcp-http: expose OpenAPI and plain HTTP APIs as MCP tools, with derived tool annotations (read-only, destructive, idempotent, open-world hints).
    • The mcp proxy provides agent-callable tool search (search_tools, describe_tool, execute_tool) with relevance ranking, a configurable eagerly-loaded tool set with pluggable by-size and by-usage policies, semantic tool search backed by a pluggable embedding provider (IBM watsonx.ai, AWS Bedrock, or OpenAI), tools/call argument validation against the cached tool schema, resources/subscribe pass-through, elicitation support, and disambiguated tool titles across toolkits.
    • Multi-node MCP gateway deployments are supported out of the box, including stateful MCP sessions, simplifying MCP load balancer configuration.
  • New vault types: aws-kms, hashicorp (Vault Transit engine), kmip, and k8s-secrets.
  • New guards: aws-cognito (AWS Cognito JWT validation via OIDC discovery), aws-iam (injects AWS credentials), x509 (authorizes from a verified client certificate chain), and lookup (resolves roles and attributes for an already-authenticated identity).
  • guard-oauth: OAuth 2.1 authorization-code grant with PKCE, dynamic client registration, and a JWT-bearer grant that embeds scope as a signed assertion claim with a configurable kid.
  • Field- and payload-level data protection for avro, json, protobuf, and raw bytes/string values: disclosure control (redact, omit, mask, hash) and AES-GCM encryption, with guarded, per-field rules.
  • Kafka client: SASL/OAUTHBEARER support and guard-injected credentials.
  • Kafka Proxy: per-client Kafka topic aliasing, driven by a guard's established identity or attributes, now covers the full Kafka API surface (metadata, offsets, consumer groups, transactions, ACLs, configs, and more), plus SASL/OAUTHBEARER termination for external client connections.
  • Per-subject alias support in binding-schema-registry, consistent with Kafka Proxy's topic alias.
  • New store-redis and store-hazelcast backends, alongside store-memory, backing MQTT session state and MCP caches.
  • binding-socks and binding-smux enhancements, including connection pooling by destination.

Fixed

  • Kafka cache now evicts segments even after all consumers disconnect.
  • The Protobuf JSON codec now correctly unwraps well-known wrapper types.
  • An MQTT CONNECT with a Will message no longer crashes the whole engine, and a Will message continuation read is now bounded by its declared payload length.
  • Fixed several MQTT-to-Kafka publish/produce flow-control issues that could stall or crash an engine worker, including a merged produce window collapse on multi-partition topics and a race between the session stream and its Kafka stream.
  • Numerous Kafka Proxy protocol-framing corrections affecting padding, varint sizing, per-connection API version negotiation, and Fetch/Produce edge cases.