ClusterJ cannot connect to dockerized Mysql cluster from outside the container - docker

Question

I have setup MySQL cluster on my PC using mysql/mysql-cluster image on docker hub, and it starts up fine. However when I try to connect to the cluster from outside docker (via the host machine) using clusterJ it doesn't connect.
Initially I was getting the following error: Could not alloc node id at 127.0.0.1 port 1186: No free node id found for mysqld(API)
So I created a custom mysql-cluster.cnf, very similar to the one distributed with the docker image, but with a new api endpoint:
[ndbd default]
NoOfReplicas=2
DataMemory=80M
IndexMemory=18M
[ndb_mgmd]
NodeId=1
hostname=192.168.0.2
datadir=/var/lib/mysql
[ndbd]
NodeId=2
hostname=192.168.0.3
datadir=/var/lib/mysql
[ndbd]
NodeId=3
hostname=192.168.0.4
datadir=/var/lib/mysql
[mysqld]
NodeId=4
hostname=192.168.0.10
[api]
This is the configuration used for clusterJ setup:
com.mysql.clusterj.connect:
host: 127.0.0.1:1186
database: my_db
Here is the docker-compose config:
version: '3'
services:
#Sets up the MySQL cluster ndb_mgmd process
database-manager:
image: mysql/mysql-cluster
networks:
database_net:
ipv4_address: 192.168.0.2
command: ndb_mgmd
ports:
- "1186:1186"
volumes:
- /c/Users/myuser/conf/mysql-cluster.cnf:/etc/mysql-cluster.cnf
# Sets up the first MySQL cluster data node
database-node-1:
image: mysql/mysql-cluster
networks:
database_net:
ipv4_address: 192.168.0.3
command: ndbd
depends_on:
- database-manager
# Sets up the second MySQL cluster data node
database-node-2:
image: mysql/mysql-cluster
networks:
database_net:
ipv4_address: 192.168.0.4
command: ndbd
depends_on:
- database-manager
#Sets up the first MySQL server process
database-server:
image: mysql/mysql-cluster
networks:
database_net:
ipv4_address: 192.168.0.10
environment:
- MYSQL_ALLOW_EMPTY_PASSWORD=true
- MYSQL_DATABASE=my_db
- MYSQL_USER=my_user
command: mysqld
networks:
database_net:
ipam:
config:
- subnet: 192.168.0.0/16
When I try to connect to the cluster I get the following error: '127.0.0.1:1186' nodeId 0; Return code: -1 error code: 0 message: .
I can see that the app running ClusterJ is registered to the cluster, but then it disconnects. Here is a excerpt from the docker mysql manager logs:
database-manager_1 | 2018-05-10 11:18:43 [MgmtSrvr] INFO -- Node 3: Communication to Node 4 opened
database-manager_1 | 2018-05-10 11:22:16 [MgmtSrvr] INFO -- Alloc node id 6 succeeded
database-manager_1 | 2018-05-10 11:22:16 [MgmtSrvr] INFO -- Nodeid 6 allocated for API at 10.0.2.2
Any help solving this issue would be much appreciated.

Answer 1

Here is how ndb_mgmd handles the request to start the ClusterJ application.
You connect to the MGM server on port 1186. In this connection you
will get the configuration. This configuration contains the IP addresses
of the data nodes. To connect to the data nodes ClusterJ will try to
connect to 192.168.0.3 and 192.168.0.4. Since ClusterJ is outside Docker,
I presume those addresses point to some different place.
The management server will also provide a dynamic port to use when
connecting to the NDB data node. It is a lot easier to manage this
by setting ServerPort for NDB data nodes. I usually use 11860 as
ServerPort, 2202 is also popular to use.
I am not sure how you mix a Docker environment with an external
environment. I assume it is possible to solve somehow by setting
up proper IP translation tables in the correct places.