CODEWITHSUNDEEP
dockerdocker-compose
Pallav Jha
Pallav Jha

Reputation: 3619

docker compose: No assignment of host names when bridge is used

In order to make every container part of the default bridge, I added network_mode: bridge in every service. These became part of bridge but the containers are not getting attached with the hostnames. Below is the config.

docker-compose.yml

version: '2'

services:

  elasticsearch:
    build:
      context: elasticsearch/
      args:
        ELK_VERSION: $ELK_VERSION
    volumes:
      - ./elasticsearch/config/elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml:ro
    ports:
      - "9200:9200"
      - "9300:9300"
    environment:
      ES_JAVA_OPTS: "-Xmx256m -Xms256m"
    network_mode: bridge
    hostname: elasticsearch

  logstash:
    build:
      context: logstash/
      args:
        ELK_VERSION: $ELK_VERSION
    volumes:
      - ./logstash/config/logstash.yml:/usr/share/logstash/config/logstash.yml:ro
      - ./logstash/pipeline:/usr/share/logstash/pipeline:ro
    ports:
      - "5000:5000"
      - "9600:9600"
    environment:
      LS_JAVA_OPTS: "-Xmx256m -Xms256m"
    network_mode: bridge
    depends_on:
      - elasticsearch

  kibana:
    build:
      context: kibana/
      args:
        ELK_VERSION: $ELK_VERSION
    volumes:
      - ./kibana/config/:/usr/share/kibana/config:ro
    ports:
      - "5601:5601"
    network_mode: bridge
    depends_on:
      - elasticsearch

Docker compose up

$ docker-compose up -d
Creating docker-elk_elasticsearch_1 ... done
Creating docker-elk_kibana_1        ... done
Creating docker-elk_logstash_1      ... done

Docker network inspect

$ docker network inspect bridge
[
    {
        "Name": "bridge",
        "Id": "f561a85fb2b22bbf251545c7021d57020cf152bd3a5c3c061c7d6b0cb4e267e5",
        "Created": "2018-09-19T07:02:49.36259364Z",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.17.0.0/16",
                    "Gateway": "172.17.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "0aedc2ce900b8a51f028e58a85c8db9480fd2816874a608540a899a4daab32fd": {
                "Name": "docker-elk_kibana_1",
                "EndpointID": "df3af338e0accb880ccc44323e5581064ee8ef84574485f1928d12dc415b598e",
                "MacAddress": "02:42:ac:11:00:05",
                "IPv4Address": "172.17.0.5/16",
                "IPv6Address": ""
            },
            "3f2088847bd8e958a047093b1af879c91c4071f57f0105bb7bf80fb8df832d41": {
                "Name": "docker-elk_logstash_1",
                "EndpointID": "6588b7eece43144833ae2f9ffe753e3cc6c70d0891a587c3e9a4e9ca84993532",
                "MacAddress": "02:42:ac:11:00:06",
                "IPv4Address": "172.17.0.6/16",
                "IPv6Address": ""
            },
            "ace35bb6fadd50823f64e9075b5972e6e3b24e8b73273a41e7a48f9eeff89da1": {
                "Name": "roach",
                "EndpointID": "dd058e3e9f46b2459f14a2e5bdf96eae277e81dcf7ac2e6ac1c97d8220ead30d",
                "MacAddress": "02:42:ac:11:00:03",
                "IPv4Address": "172.17.0.3/16",
                "IPv6Address": ""
            },
            "f90378063d2a0157110b77af39f2526347f1ea9634839e0d2c0c584fb14ff957": {
                "Name": "docker-elk_elasticsearch_1",
                "EndpointID": "294a2f67196788135f370bbf83526395ba4401afb25db9eb0b59fba7fd358912",
                "MacAddress": "02:42:ac:11:00:04",
                "IPv4Address": "172.17.0.4/16",
                "IPv6Address": ""
            },
            "f954c218e5ab15c83c2a0e2c848549c18879613f6f46d07f7ebf71cc89b6e55b": {
                "Name": "rabbitmq",
                "EndpointID": "e675ddc6076fe2256553e8b367a82aa36f488457e06ae6cf969c2e04feeb9fb8",
                "MacAddress": "02:42:ac:11:00:02",
                "IPv4Address": "172.17.0.2/16",
                "IPv6Address": ""
            }
        },
        "Options": {
            "com.docker.network.bridge.default_bridge": "true",
            "com.docker.network.bridge.enable_icc": "true",
            "com.docker.network.bridge.enable_ip_masquerade": "true",
            "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
            "com.docker.network.bridge.name": "docker0",
            "com.docker.network.driver.mtu": "1500"
        },
        "Labels": {}
    }
]

Docker inspect elasticsearch

$ docker inspect docker-elk_elasticsearch_1
"NetworkSettings": {
            "Bridge": "",
            "SandboxID": "31a438f8fcb3dd8efca37260e77d346f21239b36d8bb30f5f08db4b79880a5c9",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": {
                "9200/tcp": [
                    {
                        "HostIp": "0.0.0.0",
                        "HostPort": "9200"
                    }
                ],
                "9300/tcp": [
                    {
                        "HostIp": "0.0.0.0",
                        "HostPort": "9300"
                    }
                ]
            },
            "SandboxKey": "/var/run/docker/netns/31a438f8fcb3",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "294a2f67196788135f370bbf83526395ba4401afb25db9eb0b59fba7fd358912",
            "Gateway": "172.17.0.1",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "172.17.0.4",
            "IPPrefixLen": 16,
            "IPv6Gateway": "",
            "MacAddress": "02:42:ac:11:00:04",
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": null,
                    "NetworkID": "f561a85fb2b22bbf251545c7021d57020cf152bd3a5c3c061c7d6b0cb4e267e5",
                    "EndpointID": "294a2f67196788135f370bbf83526395ba4401afb25db9eb0b59fba7fd358912",
                    "Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.4",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:11:00:04",
                    "DriverOpts": null
                }
            }
        }

Kibana Logs where elastic search is inaccessible:

$ docker logs docker-elk_kibana_1

{"type":"log","@timestamp":"2018-09-20T05:27:05Z","tags":["warning","elasticsearch","admin"],"pid":1,"message":"Unable to revive connection: http://elasticsearch:9200/"}
{"type":"log","@timestamp":"2018-09-20T05:27:05Z","tags":["warning","elasticsearch","admin"],"pid":1,"message":"No living connections"}

However, everything works fine with below config where I haven't provided any network related config.

version: '2'

services:

  elasticsearch:
    build:
      context: elasticsearch/
      args:
        ELK_VERSION: $ELK_VERSION
    volumes:
      - ./elasticsearch/config/elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml:ro
    ports:
      - "9200:9200"
      - "9300:9300"
    environment:
      ES_JAVA_OPTS: "-Xmx256m -Xms256m"

  logstash:
    build:
      context: logstash/
      args:
        ELK_VERSION: $ELK_VERSION
    volumes:
      - ./logstash/config/logstash.yml:/usr/share/logstash/config/logstash.yml:ro
      - ./logstash/pipeline:/usr/share/logstash/pipeline:ro
    ports:
      - "5000:5000"
      - "9600:9600"
    environment:
      LS_JAVA_OPTS: "-Xmx256m -Xms256m"
    depends_on:
      - elasticsearch

  kibana:
    build:
      context: kibana/
      args:
        ELK_VERSION: $ELK_VERSION
    volumes:
      - ./kibana/config/:/usr/share/kibana/config:ro
    ports:
      - "5601:5601"
    depends_on:
      - elasticsearch

Upvotes: 1

Views: 2501

Answers (1)

takacsmark
takacsmark

Reputation: 4441

Containers on the default bridge network cannot refer each other by host name, they can only refer each other by IP. You can find this in the docs here https://docs.docker.com/network/bridge/#differences-between-user-defined-bridges-and-the-default-bridge.

Containers on the default bridge network can only access each other by IP addresses, unless you use the --link option, which is considered legacy. On a user-defined bridge network, containers can resolve each other by name or alias.

The solution is to define your custom bridge network in the Compose file with networks as described here https://docs.docker.com/compose/compose-file/#networks and add every container to this user defined network. On this network containers can resolve each other by name.

Upvotes: 5

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