Docker containers in same network can't communicate

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1

I have two containers mongo and mongo-express in the same network, the issue here is that this setup works fine on windows/ubuntu but for some reason on redhat linux mongo-express can not connect to mongo even though they are in the same network.

below are the compose file and Dockerfile i am using

services:
  mongo:
    container_name: mongo
    build:
      context: ./mongo
      dockerfile: Dockerfile
    environment:
      - MONGO_INITDB_ROOT_USERNAME=root
      - MONGO_INITDB_ROOT_PASSWORD=root
    volumes:
      - mongo:/bitnami/mongodb
    healthcheck:
      test: echo 'db.runCommand("ping").ok' | mongosh localhost:27017/test --quiet
      interval: 10s
      timeout: 10s
      retries: 5
      start_period: 40s
    networks:
      - mongoNetwork
      
  mongo-init:
    container_name: mongo-init
    image: mongo:7.0
    depends_on:
      mongo:
        condition: service_healthy
    entrypoint: "mongosh --host mongo -u root -p root --authenticationDatabase admin --eval \"rs.initiate({_id: 'mongo',members: [{_id: 0, host: 'mongo'}]})\""
    networks:
      - mongoNetwork

  mongo-express:
    container_name: mongo-express
    image: mongo-express
    restart: always
    ports:
      - 8081:8081
    depends_on:
      mongo:
        condition: service_healthy
    environment:
      ME_CONFIG_MONGODB_ADMINUSERNAME: root
      ME_CONFIG_MONGODB_ADMINPASSWORD: root
      ME_CONFIG_MONGODB_URL: mongodb://root:root@mongo:27017/lhivedb?authMechanism=SCRAM-SHA-256&authSource=admin&replicaSet=mongo
      ME_CONFIG_BASICAUTH: false
    networks:
      - mongoNetwork

FROM mongo:8.0-rc

WORKDIR /app

# generating the keyfile for replicaset
RUN openssl rand -base64 756 > keyFile

# changing the permission and ownership of the key file
RUN chmod 400 /app/keyFile
RUN chown mongodb:mongodb /app/keyFile

# Command to start MongoDB with the specified options
CMD ["mongod", "--bind_ip_all", "--port", "27017", "--replSet", "mongo", "--keyFile", "/app/keyFile"]

logs:

root@ksfilesvr Mongo]# docker logs -f mongo-express
Waiting for mongo:27017...
/docker-entrypoint.sh: connect: Operation timed out
/docker-entrypoint.sh: line 15: /dev/tcp/mongo/27017: Operation timed out
Mon Aug 19 16:44:28 UTC 2024 retrying to connect to mongo:27017 (2/10)
^Ccontext canceled
[root@ksfilesvr Mongo]# docker logs -f mongo-init
MongoServerSelectionError: Server selection timed out after 30000 ms
[root@ksfilesvr Mongo]#

docker network inspect

[
    {
        "Name": "mongo_mongoNetwork",
        "Id": "e886244e7da2ccda3f46ef048ad0d064ae46b9c052b5da3b773a93d164ac5387",
        "Created": "2024-08-20T01:42:04.024591421+09:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "2f43ccee0999d8bf52e3ee7f120d87c82687ab9223da5153c0e00c89a3cc52b4": {
                "Name": "mongo",
                "EndpointID": "73b8779696a8d5f15a222c10492476b4f7a24e3b9ea3a46876619d81887ec3ad",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            },
            "32818def7ba0f5fc9381e2fc363e3d5a24492aa989d8ba464ca3f3600875dcb8": {
                "Name": "mongo-express",
                "EndpointID": "9ac3b9ac17eb5fb07bdfac6bfe34eae509e233836b32872a9b4b0b7bbf1d30cb",
                "MacAddress": "02:42:ac:12:00:04",
                "IPv4Address": "172.18.0.4/16",
                "IPv6Address": ""
            },
            "ee055db37bd437de1178866d6449767ef8f84a85c6074276926094b7bc4a555d": {
                "Name": "mongo-init",
                "EndpointID": "e30e79da551da3139ba662c0d83de6101126c67b7b9046f64ecd92d7618f43b2",
                "MacAddress": "02:42:ac:12:00:03",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {
            "com.docker.compose.network": "mongoNetwork",
            "com.docker.compose.project": "mongo",
            "com.docker.compose.version": "2.29.1"
        }
    }
]
2

Check your firewall settings. Possibly firewalld. on a Red Hat based system.

Some info

I had issues years agon on CentOS caused by firewalld.

3

I checked that and firewalld is already disabled

4

Check both container Ips are in the same network subnet (bridge or overlay)
disable selinux , firewall
get inside shell using exec and try to ping each container to another.
on windows firewall(Not recommended) either disable or add inbound/outbound required ports