Correct way to start docker daemon listening to specific port

Question

I´m new to docker and want to start it in daemon mode listening to a specific IP-adress and port. In the documentation it is said that this can be done by writing sudo /usr/bin/docker daemon -H 0.0.0.0:5555. It then says that I can list running containers with this command docker ps. If I try this I get the following message:

Get http:///var/run/docker.sock/v1.20/containers/json?all=1: dial unix /var/run/docker.sock: no such file or directory.

• Are you trying to connect to a TLS-enabled daemon without TLS?
• Is your docker daemon up and running?

I cannot interact with it. I´ve searched for a solution but with no luck. Any suggestions?

P.S. How can I run this daemon in background? I tried appending an & but I´m stuck on the ouput till pressing ctrl+c.

Thanks in advance

Answer 1

On Ubuntu (16.04 LTS) with docker-ce (17.03.1~ce-0~ubuntu-xenial) do the following to make docker listen to a TCP port instead of sockets.

Add a file /etc/systemd/system/docker.service.d/override.conf with the following content:

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd

Add a file /etc/docker/daemon.json with the following content

{
    "hosts": [
        "tcp://127.0.0.1:2375"
    ] 
}

Reload (systemctl daemon-reload) and restart (systemctl restart docker.service) docker.

For reference: https://github.com/moby/moby/issues/25471

EDIT:

Be careful, so the demon will only listen to that network port ignoring local requests. To make docker listen to both remote and local, edit daemon.json but keep the standard unix socket

{
        "hosts" : [
                "unix:///var/run/docker.sock",
                "tcp://<docker-host-ip-or-localhost>:2375"
        ]
}

Docker daemon connection options docs

Answer 2

On Mac OSX you'd run the Docker Quickstart Terminal App to see:

Machine default already exists in VirtualBox.
Starting machine default...
Started machines may have new IP addresses. You may need to re-run the `docker-machine env` command.
Setting environment variables for machine default...

...

                        ##         .
                  ## ## ##        ==
               ## ## ## ## ##    ===
           /"""""""""""""""""\___/ ===
      ~~~ {~~ ~~~~ ~~~ ~~~~ ~~~ ~ /  ===- ~~~
           \______ o           __/
             \    \         __/
              \____\_______/


docker is configured to use the default machine with IP 192.168.99.100
For help getting started, check out the docs at https://docs.docker.com

now

docker ps

should work

On Linux e.g. Ubuntu prepending sudo might be necessary. E.g.

docker ps

will lead to:

Get http:///var/run/docker.sock/v1.20/containers/json: dial unix /var/run/docker.sock: permission denied.
* Are you trying to connect to a TLS-enabled daemon without TLS?
* Is your docker daemon up and running?

but

sudo docker ps

will work.

See https://docs.docker.com/articles/basics/

To check if your docker service is running you can call

 sudo service --status-all 2>&1 | grep docker

and it should show:

[ - ]  docker

Sometimes your docker instllation might be corrupt see: Docker daemon does not start or restart

Answer 3

I found a solution to my problem. I specified docker running on IP x and Port y, but docker then only listens to that socket. I had to add another -H flag with the unix socket in order to listen to local requests:

sudo /usr/bin/docker daemon -H tcp://0.0.0.0:5555 -H unix:///var/run/docker.sock