Not forming cluster with docker stack and DNSRR

[georgeaniljohn]

Seems the hazelcast is not forming a cluster when service deployed in a docker stack using method DNSRR with the help of a docker-compose file. Each node now acts as an individual master.

But working perfectly fine when service deployed outside stack as

docker service create --network sample-net --name sample-node --endpoint-mode dnsrr --restart-condition on-failure --constraint 'node.hostname !=sample-machine-3' --replicas 2 -e "SPRING_DATA_MONGODB_URI=mongodb://10.10.30.31:27017,10.10.30.32:27017,10.10.30.33:27017/sampledb" -e "HZ_MANCENTER_URI=http://10.10.30.33:8080/mancenter" -e "HZ_GROUP=live-sample" -e "JAVA_OPTS=-DserviceName=sample-node -DservicePort=6781 -DpeerServicesCsv=sample-node:6781" sample-registry:5000/sampleimage:latest

[bitsofinfo]

@Cardds can you assist w/ this please?

[Cardds]

@georgeaniljohn Can the stack file be posted, with associated network information & related configuration?

[georgeaniljohn]

@Cardds The network is being created by running the script:

docker network create --driver=overlay sample-net

---

docker-compose file for the stack:

version: "3.5"

networks: sample-net: external: true

services: mongodb1: hostname: mongodb1 image: "sample-registry:5000/mongodb:latest" deploy: restart_policy: condition: on-failure ports:

• "27017:27017" volumes:

  • "/data/mongodb1:/data/db" environment:
  • "SERVICE_NAME=mongodb1" networks:
  • sample-net

  mongodb2: hostname: mongodb2 image: "sample-registry:5000/mongodb:latest" deploy: restart_policy: condition: on-failure ports:

  • "28018:27017" volumes:
  • "/data/mongodb2:/data/db" environment:
  • "SERVICE_NAME=mongodb2" networks:
  • sample-net

  mongodb3: hostname: mongodb3 image: "sample-registry:5000/mongodb:latest" deploy: restart_policy: condition: on-failure ports:

• "29019:27017" volumes:

  • "/data/mongodb3:/data/db" environment:
  • "SERVICE_NAME=mongodb3" networks:
  • sample-net

  sample-node: hostname: sample-node image: "sample-registry:5000/node:latest" deploy: mode: replicated replicas: 2 restart_policy: condition: on-failure endpoint_mode: dnsrr depends_on:

  • mongodb1
  • mongodb2
  • mongodb3 environment:
  • "SPRING_DATA_MONGODB_URI=mongodb://mongodb1:27017,mongodb2:27017,mongodb3:27017/sampledb"
  • "HZ_MANCENTER_URI=http://hazelcastmc:8080/mancenter"
  • "HZ_GROUP=live-sample"
  • "JAVA_OPTS=-DpeerServicesCsv=sample-node:6781 -DserviceName=sample-node -DservicePort=6781" networks:
  • sample-net

[Cardds]

@georgeaniljohn The file posted does not appear to have any reference to specifying the endpoint_mode as dnsrr. See https://docs.docker.com/compose/compose-file/#endpoint_mode for associated docker compose documentation; note there it was only introduced in stack files as of verison 3.3.

[georgeaniljohn]

@Cardds sorry that it was missed out when posting initially and I updated it now. The issue got resolved now after specifying the entire service name along with stack name. eg: -DserviceName=stack-name_sample-node. But thank you for reaching out .