2.1.0

New features

• The tracing configuration has been extended to now also support a rate-limiting sampler. See the Monitoring & Tracing guide for details.
• Add new metric for tracking the total number of Tenants in Hono.
• The Auth server component now provides an HTTP endpoint for retrieving the keys that applications should use for
  validating the signature of tokens issued by the Auth server. The keys are being transferred by means of a
  JSON Web Key set as defined by RFC 7517. The Device Registry and
  Command Router components will use this endpoint to periodically download the keys if no key material has been configured
  explicitly.
• The handling of messages that have no payload and/or no content type has been harmonized across the protocol adapters.
  Adapters now uniformly accept messages from devices that have no payload if the device explicitly sets a non-empty content
  type on the message. Messages with a non-empty payload can be uploaded without specifying a content type. In the messages
  being forwarded to downstream consumers, the adapters will either use the devices's default content type, if defined, or
  otherwise fall back to application/octet-stream in such cases.
• A Linux x86_64 executable of the command line client has been added to the downloads page.

Fixes & Enhancements

• The CoAP adapter did not properly consider the reduced minimum RAM requirements for starting up when running as a
  native executable on a SubstrateVM. This could have resulted in the adapter not starting up at all, if configured
  with less than ~150MB of RAM. This has been fixed.
• The HTTP protocol adapter and Device Registry now support a configuration property for explicitly setting a request's
  idle timeout. The timeout is configured with the property idleTimeout. This determines if a request will time out
  and be closed if no data is received or sent within the idle timeout period. The idle timeout is in seconds.
  A zero value means no timeout is used.
• The MQTT adapter skipped command or error (the first one) subscription if both were requested for the same device.
  This has been fixed.
• On startup, Hono components could get into a state that caused certain Kafka client metrics to not get reported.
  This has been fixed.
• Default messaging type changed to Kafka. Changed related documentation pages.
• The native executable based Lora adapter container image failed to forward Lora meta information in messages being
  sent downstream. This has been fixed.
• The Command Router component might not have reached the ready state in case the Kafka broker got restarted during
  Command Router startup. This has been fixed.
• The mechanism used by the Command Router component to determine the state of protocol adapter instances has been
  improved.
• The CoAP adapter returned a 500 error code for PUT requests without a device identifier in the URI path. This has
  been fixed, now returning a response with a 404 error code instead.
• The command line client no longer throws an NPE when trying to upload an empty message without a content type to the
  AMQP adapter.