Unable to ping docker container

Question

New to docker on mac osx. I am building a ubuntu image from the base phusion image to use as a git server. Using the following file to install the base and needed software. This works great. However, I am unable to ping the machine.

EDIT

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I am unable to ping the machine. I can run the image and see the container in the ps command. I can also exec bash into it.

CONTAINER ID        IMAGE               COMMAND               CREATED             STATUS              PORTS               NAMES
54e4cef78445        git-ssh_img         "/usr/sbin/sshd -D"   44 minutes ago      Up 44 minutes       22/tcp              git-ssh

The following also works

docker exec -it 54e4cef78445 ping www.google.com
PING www.google.com (173.194.219.147) 56(84) bytes of data.
64 bytes from ya-in-f147.1e100.net (173.194.219.147): icmp_seq=1 ttl=61 time=65.1 ms
64 bytes from ya-in-f147.1e100.net (173.194.219.147): icmp_seq=2 ttl=61 time=67.1 ms

---

Dockerfile:

# Use phusion/baseimage as base image. To make your builds reproducible, make
# sure you lock down to a specific version, not to `latest`!
# See https://github.com/phusion/baseimage-docker/blob/master/Changelog.md for
# a list of version numbers.
FROM phusion/baseimage:0.9.18

# Use baseimage-docker's init system.
CMD ["/sbin/my_init"]

# ...put your own build instructions here...

ENV TERM xterm

RUN apt-get -y update
RUN apt-get -y install openssh-server
RUN apt-get -y install git \
    libxml2-dev \
    python \
    build-essential \
    make \
    gcc \
    python-dev \
    python-pip

# Clean up APT when done.
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Setting openssh
# RUN mkdir /var/run/sshd
RUN sed -i "s/#PasswordAuthentication yes/PasswordAuthentication no/" /etc/ssh/sshd_config

# Adding git user
RUN adduser --system git
RUN mkdir -p /home/git/.ssh

# Clearing and setting authorized ssh keys
RUN echo '' > /home/git/.ssh/authorized_keys
RUN echo 'First key' >> /home/git/.ssh/authorized_keys
# RUN echo 'Second SSH public key' >> /home/git/.ssh/authorized_keys
# ...

# Updating shell to bash
RUN sed -i s#/home/git:/bin/false#/home/git:/bin/bash# /etc/passwd

EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]

Inspect command:

[
{
    "Id": "54e4cef78445e1308b744297edc1d3d153932ce7724e87b35dc3690f8ffe41a2",
    "Created": "2015-12-10T21:01:16.683875853Z",
    "Path": "/usr/sbin/sshd",
    "Args": [
        "-D"
    ],
    "State": {
        "Running": true,
        "Paused": false,
        "Restarting": false,
        "OOMKilled": false,
        "Dead": false,
        "Pid": 13930,
        "ExitCode": 0,
        "Error": "",
        "StartedAt": "2015-12-10T21:01:16.763739339Z",
        "FinishedAt": "0001-01-01T00:00:00Z"
    },
    "Image": "b2c6f9604ceca1e112dc0560aa4d0c50596d27c80256c544613f1d6badf6ccda",
    "NetworkSettings": {
        "Bridge": "",
        "EndpointID": "87f12f9b527f3e0d7f823f1e2c88b0d0e860ff2d1687568d0a15cfa9fdfe22c3",
        "Gateway": "172.17.42.1",
        "GlobalIPv6Address": "",
        "GlobalIPv6PrefixLen": 0,
        "HairpinMode": false,
        "IPAddress": "172.17.0.26",
        "IPPrefixLen": 16,
        "IPv6Gateway": "",
        "LinkLocalIPv6Address": "",
        "LinkLocalIPv6PrefixLen": 0,
        "MacAddress": "02:42:ac:11:00:1a",
        "NetworkID": "a60ea78a8239baed013f9bfb1b2719a599ddef7745170e3c17eeab743a391ebe",
        "PortMapping": null,
        "Ports": {
            "22/tcp": null
        },
        "SandboxKey": "/var/run/docker/netns/54e4cef78445",
        "SecondaryIPAddresses": null,
        "SecondaryIPv6Addresses": null
    },
    "ResolvConfPath": "/mnt/sda1/var/lib/docker/containers/54e4cef78445e1308b744297edc1d3d153932ce7724e87b35dc3690f8ffe41a2/resolv.conf",
    "HostnamePath": "/mnt/sda1/var/lib/docker/containers/54e4cef78445e1308b744297edc1d3d153932ce7724e87b35dc3690f8ffe41a2/hostname",
    "HostsPath": "/mnt/sda1/var/lib/docker/containers/54e4cef78445e1308b744297edc1d3d153932ce7724e87b35dc3690f8ffe41a2/hosts",
    "LogPath": "/mnt/sda1/var/lib/docker/containers/54e4cef78445e1308b744297edc1d3d153932ce7724e87b35dc3690f8ffe41a2/54e4cef78445e1308b744297edc1d3d153932ce7724e87b35dc3690f8ffe41a2-json.log",
    "Name": "/git-ssh",
    "RestartCount": 0,
    "Driver": "aufs",
    "ExecDriver": "native-0.2",
    "MountLabel": "",
    "ProcessLabel": "",
    "AppArmorProfile": "",
    "ExecIDs": null,
    "HostConfig": {
        "Binds": null,
        "ContainerIDFile": "",
        "LxcConf": [],
        "Memory": 0,
        "MemorySwap": 0,
        "CpuShares": 0,
        "CpuPeriod": 0,
        "CpusetCpus": "",
        "CpusetMems": "",
        "CpuQuota": 0,
        "BlkioWeight": 0,
        "OomKillDisable": false,
        "MemorySwappiness": -1,
        "Privileged": false,
        "PortBindings": {},
        "Links": null,
        "PublishAllPorts": false,
        "Dns": null,
        "DnsSearch": null,
        "ExtraHosts": null,
        "VolumesFrom": null,
        "Devices": [],
        "NetworkMode": "default",
        "IpcMode": "",
        "PidMode": "",
        "UTSMode": "",
        "CapAdd": null,
        "CapDrop": null,
        "GroupAdd": null,
        "RestartPolicy": {
            "Name": "no",
            "MaximumRetryCount": 0
        },
        "SecurityOpt": null,
        "ReadonlyRootfs": false,
        "Ulimits": null,
        "LogConfig": {
            "Type": "json-file",
            "Config": {}
        },
        "CgroupParent": "",
        "ConsoleSize": [
            0,
            0
        ]
    },
    "GraphDriver": {
        "Name": "aufs",
        "Data": null
    },
    "Mounts": [],
    "Config": {
        "Hostname": "54e4cef78445",
        "Domainname": "",
        "User": "",
        "AttachStdin": false,
        "AttachStdout": true,
        "AttachStderr": true,
        "ExposedPorts": {
            "22/tcp": {}
        },
        "Tty": false,
        "OpenStdin": false,
        "StdinOnce": false,
        "Env": [
            "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
            "TERM=xterm"
        ],
        "Cmd": [
            "/usr/sbin/sshd",
            "-D"
        ],
        "Image": "git-ssh_img",
        "Volumes": null,
        "WorkingDir": "",
        "Entrypoint": null,
        "OnBuild": null,
        "Labels": {}
    }
}
]

Answer 1

As mentioned in "Can't visit http://172.17.0.2:5000 after starting docker registry", you cannot use the internal IP made for container-to-container communication.

You need to use the IP returned by $(docker-machine ip <yourMachine>) to actually ping the machine which runs your container.

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Update February 2017, docker 1.13+: as commented by kboom, you now have Docker for Mac which uses a lightweight hypervisor (HyperKit), which allows to be bound to localhost (but still you cannot visit internal addresses).