v4.4.19

Release Date: 2023-06-27

Enhancements

• Added support for TCP keep-alive in MQTT/TCP and MQTT/SSL listeners #10854.

  A new configuration option has been added: zone.<zone-name>.tcp_keepalive = Idle,Interval,Probes. Users can enable the TCP layer's Keep Alive feature and specify time parameters using this configuration. This configuration is only effective on Linux and MacOS systems.

• Improved error logs related to Proxy Protocol emqx/esockd#177.

  The sample logs before this improvement:

  2023-04-20T14:56:51.671735+08:00 [error] supervisor: 'esockd_connection_sup - <0.2537.0>', errorContext: connection_shutdown, reason: {invalid_proxy_info,<<"f\n">>}, offender: [{pid,<0.3192.0>},{name,connection},{mfargs,{...}}]
  
  2023-04-20T14:57:01.348275+08:00 [error] supervisor: 'esockd_connection_sup - <0.2537.0>', errorContext: connection_shutdown, reason: {proxy_proto_timeout,5000}, offender: [{pid,<0.3194.0>},{name,connection},{mfargs,{...}}]
  

  After the improvement:

  2023-04-20T18:07:06.180134+08:00 [error] [esockd_proxy_protocol] The listener 127.0.0.1:8883 is working in proxy protocol mode, but received invalid proxy_protocol header, raw_bytes=<<"f\n">>
  
  2023-04-20T18:10:17.205436+08:00 [error] [esockd_proxy_protocol] The listener 127.0.0.1:8883 is working in proxy protocol mode, but timed out while waiting for proxy_protocol header
  

• Added a new feature to enable partial certificate chain validation for TLS listeners #10553.

  For details please checkout the listener.ssl.external.partial_chain in the emqx.conf config file.

• Added a new feature to enable client certificate extended key usage validation for TLS listeners #10669.

  For details please checkout the listener.ssl.external.verify_peer_ext_key_usage in the emqx.conf config file.

• Added the live_connections field in the HTTP API /api/v4/nodes response #10859.

  Previously, this interface had a connections field, which represented the number of active connections on the current node that had not expired. This means that even if the MQTT connection has been disconnected, as long as the client has a persistent session, it would still be counted in the connections field. The newly added live_connections field specifically counts the number of clients with MQTT connections that have not been disconnected.

• Added 3 random SQL functions to the rule engine #11113.

  • random(): Generates a random number between 0 and 1 (0.0 =< X < 1.0).
  • uuid_v4(): Generates a random UUID (version 4) string.
  • uuid_v4_no_hyphen(): Generates a random UUID (version 4) string without hyphens.

• Added numerical range validation (23-65535) for the mqtt.max_clientid_len configuration parameter #11096.

Bug fixes

• Fixed an issue where the rule engine was unable to access variables exported by FOREACH in the DO clause #10620.

  Given a payload: {"date": "2023-05-06", "array": ["a"]}, as well as the following SQL statement:

  FOREACH payload.date as date, payload.array as elem
  DO date, elem
  FROM "t/#"
  

  Prior to the fix, the date variable exported by FOREACH could not be accessed in the DO clause of the above SQL, resulting in the following output for the SQL statement: [{"elem": "a","date": "undefined"}]. After the fix, the output of the SQL statement is: [{"elem": "a","date": "2023-05-06"}]

• Fixed the issue where the cache of rules failed to update in certain cases #11072.

  Prior to the fix, after manually updating the rules, there could be instances where the cache update did not synchronize to certain nodes. This would result in inconsistent rule execution states across different nodes.

• Fixed an issue where the WebHook plugin failed to execute the on_client_connack hook #10710.

  See https://github.com/emqx/emqx/issues/10628 for more details.