# Changes

# Version 4.4.6

Release Date: 2022-07-29

# Enhancement

  • Supports searching and paging of rules in rule engine
  • Provides CLI ./bin/emqx check_conf to actively check if the configuration is correct
  • Optimizing Shared Subscription Performance

# Bug fixes

  • Fix the issue that once the old version of EMQX is uninstalled after hot upgrade, EMQX will not be able to start again
  • Fix the issue that the keep-alive check for UDP clients in the Multilingual Protocol Extension was incorrect, causing clients not to expire
  • Fix the issue that the client information in the Multilingual Protocol Extension was not updated in time
  • Fix the issue that when the client specified Clean Session as false to reconnect, the shared subscription message in the flight window would be re-dispatched to the old session process
  • Fix the issue that the emqx_lua_hook plugin cannot cancel the message publishing

# Version 4.4.5

Release Date: 2022-06-30

# Enhancement

  • QoS and Retain flag in rule engine's message republish actions can now use placeholders
  • Supports exclusive subscriptions, that is, only one subscriber is allowed for a topic
  • Dashboard and management API's HTTPS listeners can now use password-protected private key files, providing key_password configuration item
  • Support for placeholders %u and %c in topic rewrite rules
  • Support setting MQTT 5.0 properties in the API request for message publishing, such as message expiry interval, response topic, etc.
  • Optimize the UI when creating rule engine resources, such as folding some uncommon options, etc.
  • Opened 4 TCP-related configuration items: KeepAlive, TCP_NODELAY, SO_RCVBUF and SO_SNDBUF for the underlying gRPC connection of ExHook

# Bug fixes

  • Fix the issue of inaccurate memory calculation in Linux OS, and calculate the memory usage of the current OS instead of the memory usage of EMQX
  • Fix the issue that the old disconnect event of ExHook would be triggered later than the new connect event when the client reconnects
  • Fix the issue that the execution order of topic rewriting and delayed publish is not fixed, now it is fixed to execute topic rewriting first
  • Fix the issue that rule engine could not encode MQTT 5.0 user properties
  • Fix the issue that the count of connack.auth_error is inaccurate when the client uses a protocol version below MQTT v5.0 to access
  • Fix the issue that the UDP listeners of LwM2M and CoAP gateways could not bind to the specified network interface
  • Fix Dashboard not starting after removing the default Dashboard user in the configuration file
  • Fix client.subscribe hook not being able to reject subscriptions
  • If the placeholder in the ACL rule is not replaced, the client's publish or subscribe operation will be rejected

# Version 4.4.4

Release Date: 2022-06-01

# Enhancement

  • Add more time transformation functions to the SQL of rule engine
  • Add the float2str/2 function to the SQL of rule engine to support specifying the output precision of floating point numbers
  • Support for using JWT for authorization, now MQTT clients can authorize using specific claims that include a pub-sub whitelist
  • Improved authentication related metrics to make it easier to understand, now client.authenticate = client.auth.success + client.auth.failure
  • Support binding the listener of the REST API to a specified network interface
  • Support multi-condition query and fuzzy query for user data in authentication and authorization using built-in database as data source
  • Supports querying clients using the length of the message queue and the number of dropped messages as conditions
  • Support to configure the log time format to be compatible with the time format in older versions
  • When use_username_as_clientid is configured to true and the client connects without specifying a username, the connection is now rejected with a reason code 0x85
  • Full randomisation of app secrets (previously partially randomised)
  • When using CLI for backup and recovery, it is no longer required that the backup file must be located in the backup folder of the EMQX data directory
  • Hot upgrades between incompatible versions will now be rejected
  • Allow white spaces in EMQX's installation path
  • Boot script fail fast on invalid node name (improve error message readability)

# Bug fixes

  • Fix the issue that rule engine's SQL function hexstr_to_bin/1 could not handle half-byte
  • Fix the issue that the alarm was not cleared when the rule engine resource was deleted
  • Fix Dashboard HTTPS listener's verify option not taking effect
  • Fix the issue that messages were lost when the peer session was terminated during the delivery of QoS 1 messages through shared subscriptions
  • Fix the issue that when the log tracer encounters large packets, the heap size grows too fast and triggers the policy of forcibly closeing the connection process
  • Fix the issue that the MQTT-SN client would be disconnected when retransmitting QoS 2 messages
  • Fix the issue that the subscriber's connection was disconnected due to the wrong user properties type in the message publishing API api/v4/mqtt/publish
  • Fix the issue that some authentication algorithms were unavailable due to the PostgreSQL driver not adapting to OTP 24
  • Fix the issue that the returned results did not match the query conditions when querying subscriptions with multiple conditions
  • Fix rule engine resource connection test not working
  • Fix multiple Dashboard display issues

# Version 4.4.3

Release Date: 2022-04-18

# Enhancement

  • Rule engine supports resetting metrics of the specified rule
  • Add connection confirmation and authorization completion events to the rule engine
  • Rule engine supports copying rule for fast reuse
  • SQL in rule engine supports zip, gzip and other compression and decompression functions
  • Improve the error message when rule engine fails to parse payload
  • Improve the connection test for some resources in rule engine
  • Support setting execution priority for ExHook
  • ExHook callback interface adds a Protobuf field RequestMeta meta to return the EMQX cluster name
  • Support local policy for shared subscriptions, which will preferentially send messages to shared subscribers under the node where messages flow in. In some scenarios, the efficiency of shared message scheduling will be improved, especially when the MQTT bridge is configured as a shared subscription
  • RSA-PSK-AES256-GCM-SHA384, RSA-PSK-AES256-CBC-SHA384, RSA-PSK-AES128-GCM-SHA256 and RSA-PSK-AES128-CBC- SHA256 four new TLS PSK cipher suites are supported, removing two insecure cipher suites PSK-3DES-EDE-CBC-SHA and PSK-RC4-SHA from the default configuration
  • Diagnostic logging for wait_for_table of mnesia
    • Prints check points of mnesia internal stats
    • Prints check points of per table loading stats, help to locate the problem of long table loading time.
  • Subscribing to an empty topic is prohibited in strict mode
  • Generate default files when loaded_modules and loaded_plugins files do not exist

# Bug fixes

  • Fix the issue that the TLS configuration item server_name_indication is set to disable and does not take effect
  • Fix potential process leak issue in MongoDB driver
  • Fix the issue that the password of the default Dashboard user modified via the CLI command would be reset after the node leaves the cluster
  • Silence grep and sed warnings in docker-entrypoint.sh
  • Fix the backup file cannot be deleted and downloaded when the API path contains ISO8859-1 escape characters
  • Fix the issue that the Redis driver would crash when DNS resolution failed, etc
  • Fix the issue that the headers field configuration in the Data to Web Server action of the rule engine did not take effect
  • Fix the issue that the MQTT Bridge plugin cannot be started when only the subscription topic is configured but QoS is not configured
  • When creating a rule, if a rule with the same ID already exists, the rules engine will now report an error instead of replacing the existing rule
  • Fix the issue that the HTTP driver process pool may not be deleted

# Version 4.4.2

Release Date: 2022-04-01

# Important changes

  • For Docker images, the configuration directory /opt/emqx/etc has been removed from the VOLUME list, making it easier for users to rebuild images with changed configurations.
  • CentOS 7 Erlang runtime rebuilt on OpenSSL-1.1.1n (previously 1.0), prior to v4.3.13, EMQX will fail to handshake and trigger malformed_handshake_data exception when clients use certain cipher suites.
  • CentOS 8 Erlang runtime system rebuilt on RockyLinux 8. centos8 will remain in the package name for backward compatibility.

# Enhancement

  • Windows package support for building on Erlang/OTP 24.
  • Add command line interface emqx_ctl pem_cache clean to allow forcibly clear x509 certificate cache to reload immediately after certificate file update.
  • Refactored ExProto so that anonymous clients can also be displayed on Dashboard.
  • Topic configuration items in bridges can now use ${node} placeholders.
  • Add validation of UTF-8 strings in MQTT packets in strict mode. When set to true, invalid UTF-8 strings will cause the client to disconnect.
  • MQTT-SN gateway supports initiative to synchronize registered topics after session resumed.
  • Improve the writing precision of rule engine floating point data from 10 decimal places to 17 decimal places.
  • EMQX will prompt how to modify the initial password of Dashboard at startup.

# Bug fixes

  • Fix the issue that the el8 installation package cannot be started on Amazon Linux 2022, the error content is errno=13 Permission denied.
  • Fix an issue where the client could not reconnect if the connection process was blocked in some cases. Now waiting for more than 15 seconds without a response will force the old connection process to be closed.
  • Fix the issue of query resource request timeout when rule engine resource is unavailable.
  • Fix the issue of {error, eexist} error when re-run after hot upgrade failed.
  • Fix an issue where publishing to a non-existing topic alias would crash the connection.
  • Fix 500 error when querying lwm2m client list on another node via HTTP API.
  • Fix HTTP API for subscribing topics crashes when invalid QoS are passed in.
  • Fix the issue that the connection count was not updated because the related resources were not released when the connection process accessed through the ExProto exited abnormally.
  • Fix an issue where the value of server_keepalive configuration item would be incorrectly applied to MQTT v3.1.1 clients.
  • Fix Stomp client not firing $event/client_connection event messages.
  • Fix the issue that the system memory alarm was incorrectly activated when EMQX was started.
  • Fixed an issue where messages that failed to be delivered due to unregistered topics were not retransmitted when topics were successfully registered with the MQTT-SN client.
  • Fix EMQX startup output error log when duplicate plugins are configured in loaded_plugins file.
  • Fix MongoDB related features outputting excessive error logs when configured incorrectly.
  • Add format check for Dashboard User and AppID, special characters such as / are not allowed.
  • Corrected the reason code in the DISCONNECT packet returned when kicking the client to 0x98.
  • Auto subscriptions will ignore empty topics.

# Version 4.4.1

Release Date: 2022-02-21

This patch release only includes a CI change for the Windows package.

# Version 4.4.0

Release Date: 2022-02-18

NOTE:

  • 4.4.0 is in sync with: 4.3.12.
  • The build of Windows package has some issues in the current version, we will fix it in the next version

The compare base of this change set is 4.3.12

# Important changes

  • For Debian/Ubuntu users, Debian/Ubuntu package (deb) installed EMQX is now started from systemd. This is to use systemd's supervision functionality to ensure that EMQX service restarts after a crash. The package installation service upgrade from init.d to systemd has been verified, it is still recommended that you verify and confirm again before deploying to the production environment, at least to ensure that systemd is available in your system

  • Package name scheme changed comparing to 4.3. 4.3 format: emqx-centos8-4.3.8-amd64.zip 4.4 format: emqx-4.4.0-rc.1-otp24.1.5-3-el8-amd64.zip

    • Erlang/OTP version is included in the package name, providing the possibility to release EMQX on multiple Erlang/OTP versions
    • centos is renamed to el. This is mainly due to centos8 being dead (replaced with rockylinux8)
  • MongoDB authentication supports DNS SRV and TXT Records resolution, which can seamlessly connect with MongoDB Altas

  • Support dynamic modification of MQTT Keep Alive to adapt to different energy consumption strategies.

  • Support 4.3 to 4.4 rolling upgrade of clustered nodes. See upgrade document for more dtails.

  • TLS for cluster backplane (RPC) connections. See clustering document for more details.

  • Add new feature for slow subscription to count the time spent in the process of message transmission, and record and display the time-consuming clients and topics.

  • Add new feature for online log tracing to support real-time tracing of client events and viewing on the dashboard.

# Minor changes

  • Bumped default boot wait time from 15 seconds to 150 seconds because in some simulated environments it may take up to 70 seconds to boot in build CI

  • Dashboard supports relative paths and custom access paths

  • Supports configuring whether to forward retained messages with empty payload to suit users who are still using MQTT v3.1. The relevant configurable item is retainer.stop_publish_clear_msg

  • Multi-language hook extension (ExHook) supports dynamic cancellation of subsequent forwarding of client messages

  • Rule engine SQL supports the use of single quotes in FROM clauses, for example: SELECT * FROM 't/#'

  • Change the default value of the max_topic_levels configurable item to 128. Previously, it had no limit (configured to 0), which may be a potential DoS threat

  • Improve the error log content when the Proxy Protocol message is received without proxy_protocol configured.

  • Add additional message attributes to the message reported by the gateway. Messages from gateways such as CoAP, LwM2M, Stomp, ExProto, etc., when converted to EMQX messages, add fields such as protocol name, protocol version, user name, client IP, etc., which can be used for multi-language hook extension (ExHook)

  • HTTP client performance improvement

  • Add openssl-1.1 to RPM dependency

# Version 4.4-beta.1

Release Date: 2021-12-21

EMQX 4.4-beta.1 is released now, it mainly includes the following changes:

Important changes:

  • Starting from 4.4, EMQX releases are named with Erlang/OTP release in the package name. e.g. emqx-4.4.0-otp24.1.5-3-centos7-arm64.rpm

  • For Debian/Ubuntu users, Debian/Ubuntu package (deb) installed EMQX now now run on systemd. This is to use systemd's supervision functionality to ensure that EMQX service restarts after a crash. The package installation service upgrade from init.d to systemd has been verified, but it is still recommended that you verify and confirm again before deploying to the production environment, at least to ensure that systemd is available in your system

  • MongoDB authentication supports DNS SRV and TXT Records resolution, which can seamlessly connect with MongoDB Altas

  • Support dynamic modification of MQTT Keep Alive to adapt to different energy consumption strategies

  • Support 4.3 to 4.4 rolling upgrade of clustered nodes. See upgrade document for more dtails.

  • TLS for cluster backplane (RPC) connections. See clustering document for details.

Minor changes:

  • Dashboard supports relative paths and custom access paths

  • Supports configuring whether to forward retained messages with empty payload to suit users who are still using MQTT v3.1. The relevant configurable item is retainer.stop_publish_clear_msg

  • Multi-language hook extension (ExHook) supports dynamic cancellation of subsequent forwarding of client messages

  • Rule engine SQL supports the use of single quotes in FROM clause, for example: SELECT * FROM't/#'

  • Change the default value of the max_topic_levels configurable item to 128. Previously, it had no limit (configured to 0), which may be a potential DoS threat

  • Improve the error log content when the Proxy Protocol message is received but the proxy_protocol configuration is not turned on

  • Add additional message attributes to the message reported by the gateway. Messages from gateways such as CoAP, LwM2M, Stomp, ExProto, etc., when converted to EMQX messages, add fields such as protocol name, protocol version, user name, client IP, etc., which can be used for multi-language hook extension (ExHook)

  • HTTP client performance improvement

  • Add openssl-1.1 to RPM dependency

Bug fixes:

  • Various RPC timeouts or even indefinite hangs, e.g. client becomes unresponsive due to the a bug in Erlang/OTP which is triggered under high load

  • Fix the issue that the lock management process ekka_locker crashes after killing the suspended lock owner

  • Fix the issue that the Path parameter of WebHook action in rule engine cannot use the rule engine variable

  • Fix MongoDB authentication module cannot use Replica Set mode and other issues

  • Fix the issue of out-of-sequence message forwarding between clusters. The relevant configurable item is rpc.tcp_client_num

  • Fix the issue of incorrect calculation of memory usage

  • Fix MQTT bridge malfunction when remote host is unreachable (hangs the connection)

  • Fix the issue that HTTP headers may be duplicated