Unable to ping docker container - docker

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
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.
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).