CODEWITHSUNDEEP
dockernetwork-programmingdocker-compose
Swurderer
Swurderer

Reputation: 179

Centos 7.9 - Docker container can't access internet

I currently have a running docker stack, with services able to communicate with each other through a bridge network.

Even if the inbound connection works (Internet --> Containers), the outbound doesn't: I am unable to wget;curl;etc towards internet, from those containers.

My host runs on Centos, and given the amount of posts related to this kind of issues online, I disabled firewalld to check if it was the issue: It wasn't.

CentOS Linux release 7.9.2009

Docker version 1.13.1, build 0be3e21/1.13.1

docker-compose version 1.28.5, build c4eb3a1f

networks:
    mynetwork:
        driver: bridge

 "Scope": "local",
    "Driver": "bridge",
    "EnableIPv6": false,
    "IPAM": {
        "Driver": "default",
        "Options": null,
        "Config": [
            {
                "Subnet": "172.19.0.0/16",
                "Gateway": "172.19.0.1"
            }
        ]
    },
    "Internal": false,
    "Attachable": true,
    "Containers": {
        [...]
    },
    "Options": {},
    "Labels": {
        "com.docker.compose.network": "mynetwork",
        "com.docker.compose.project": "myproject",
        "com.docker.compose.version": "1.28.5"
    }

Curl with url:

curl www.tester.com
curl: (6) Could not resolve host: www.tester.com

Curl with IP work though.

It seems to be related to the DNS, but I lack knowledge in this field. How can I tweak my configuration to grant access to internet to my containers ? (Without setting network: host)

EDIT:

Setting the DNS into the docker-compose file worked like a charm. Thanks @atline for the lead !

dns:
    - 8.8.8.8
dns_search:
    - domain.name

For those who have a similar issue despite setting the DNS into docker setting files (daemon / docker.service / ...), it looks like docker-compose doesn't use Docker "custom" default values; So use the docker-compose directly

Upvotes: 1

Views: 1694

Answers (1)

atline
atline

Reputation: 31684

There are several ways for you to configure dns for container:

1. Add dns when run container:

docker run --dns 192.168.1.1 busybox nslookup google.com

2. Configure /etc/docker/daemon.json to set default dns for all containers:

{
    "dns": ["192.168.1.1", "8.8.8.8"]
}

Then, sudo service docker restart to make it effect.

3. Change systemd script /lib/systemd/system/docker.service to include the --dns:

[Service]
ExecStart=/usr/bin/dockerd --dns 192.168.1.1 -H fd:// -H tcp://0.0.0.0:2375 --containerd=/run/containerd/containerd.sock

Then restart the docker to make it effect:

sudo systemctl daemon-reload
sudo systemctl restart docker
sudo systemctl status docker

NOTE: You should use your real dns to replace the value of 192.168.1.1.

Upvotes: 2

Related Questions