Hazelcast Kubernetes plugin is not defined
First of all, OrientDB version should be updated to the latest - 3.0.10 with embedded newest Hazelcast version. Also, I have mounted hazelcast-kubernetes.jar dependency file directly into /orientdb/lib folder and it started to work properly. HazelcastKubernetes plugin is discovered and nodes join the cluster:
INFO [172.17.0.3]:5701 [orientdb-test-cluster-1] [3.10.4] Kubernetes Discovery activated resolver: DnsEndpointResolver [DiscoveryService]INFO [172.17.0.3]:5701 [orientdb-test-cluster-1] [3.10.4] Activating Discovery SPI Joiner [Node]INFO [172.17.0.3]:5701 [orientdb-test-cluster-1] [3.10.4] Starting 2 partition threads and 3 generic threads (1 dedicated for priority tasks) [OperationExecutorImpl]Members {size:3, ver:3} [ Member [172.17.0.3]:5701 - hash Member [172.17.0.4]:5701 - hash Member [172.17.0.8]:5701 - hash]