HiveMQ DNS discovery plugin

This plugin can be used with any cloud environment / container orchestration environment that supports service discovery using a round-robin A records.

The following environment variables or property keys should be used to customize the discovery parameters.

If a properties file is provided (dnsdiscovery.properties in conf/ folder), the plugin will use the key-value pairs from this file and reload the values on file changes.

The plugin will attempt to load the properties file first. If it does not exist, the plugin will not attempt to reload the properties and instead try to read from the environment variables on each iteration until broker shutdown.

Environment Variable

Default value

property key

Meaning

HIVEMQ_DNS_DISCOVERY_ADDRESS

-

discoveryAddress

Address providing the A record for the usage as cluster node addresses

HIVEMQ_DNS_DISCOVERY_TIMEOUT

30

resolutionTimeout

Wait time for DNS resolution to complete

Sample DNS record

The following list shows a sample round-robin A-record as expected and parsed by the plugin:

$ dig tasks.hivemq

; <<>> DiG 9.10.3-P4-Debian <<>> tasks.hivemq
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21767
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;tasks.hivemq.          IN  A

;; ANSWER SECTION:
tasks.hivemq.       600 IN  A   10.0.0.6
tasks.hivemq.       600 IN  A   10.0.0.5
tasks.hivemq.       600 IN  A   10.0.0.4
tasks.hivemq.       600 IN  A   10.0.0.7
tasks.hivemq.       600 IN  A   10.0.0.3

This record represents a 5 node cluster on an overlay network.