Docker - Ubuntu - bash: ping: command not found

Docker images are pretty minimal, but you can install ping in your official ubuntu docker image via:

apt-get update
apt-get install iputils-ping

Chances are you don't need ping on your image, and just want to use it for testing purposes. Above example will help you out.

But if you need ping to exist on your image, you can create a Dockerfile or commit the container you ran the above commands into a new image.

Commit:

docker commit -m "Installed iputils-ping" --author "Your Name <name@domain.com>" ContainerNameOrId yourrepository/imagename:tag

Dockerfile:

FROM ubuntu
RUN apt-get update && apt-get install -y iputils-ping
CMD bash

Please note there are best practices on creating docker images, like clearing apt cache files afterwards and etc.

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This is the Docker Hub page for Ubuntu and this is how it is created. It only has (somewhat) bare minimum packages installed, thus if you need anything extra you need to install it yourself.

apt-get update && apt-get install -y iputils-ping

However usually you'd create a "Dockerfile" and build it:

mkdir ubuntu_with_ping
cat >ubuntu_with_ping/Dockerfile <<'EOF'
FROM ubuntu
RUN apt-get update && apt-get install -y iputils-ping
CMD bash
EOF
docker build -t ubuntu_with_ping ubuntu_with_ping
docker run -it ubuntu_with_ping

Please use Google to find tutorials and browse existing Dockerfiles to see how they usually do things :) For example image size should be minimized by running apt-get clean && rm -rf /var/lib/apt/lists/* after apt-get install commands.

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Alternatively you can use a Docker image which already has ping installed, e.g. busybox:

docker run --rm busybox ping SERVER_NAME -c 2

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Generally people pull the official image of Ubuntu/CentOS but they don't realize that these images are minimal and doesn't have any thing on the top of that.

For Ubuntu, this image is built from official rootfs tarballs provided by Canonical. Given that it is a minimal install of Ubuntu, this image only includes the C, C.UTF-8, and POSIX locales by default.

One can install net-tools (includes ifconfig, netstat), ip-utils(includes ping) andy other likes curl etc on container and can create image from container or can write Dockerfile that will install these tool while creating image.

Below is Dockerfile example, while creating image from this it will include these tools:

FROM vkitpro/ubuntu16.04
RUN     apt-get  update -y \
&& apt-get upgrade -y \
&& apt-get install iputils-ping -y \
&& apt-get install net-tools -y \
CMD bash

or launch container from base image and install these utilities on container and then commit to image. docker commit -m "any descriptive message" container_id image_name:lattest

That image will have all thing installed.

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Sometimes, the minimal installation of Linux in Docker doesn't define the path and therefore it is necessary to call ping using ....

cd /usr/sbin
ping <ip>

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I have used the statement below on debian 10

apt-get install iputils-ping

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Every time you get this kind of error

bash: <command>: command not found

On a host with that command already working with this solution: dpkg -S $(which )

Don't have a host with that package installed? Try this: apt-file search /bin/

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Alternatively, you can run ping on the host after entering the container's network namespace.

First, find the container's process ID on the host (this can be the shell or the application you are running inside the container). Then change to the container's network namespace (run as root on the host):

host# PS1='container# ' nsenter -t <PID> -n

Modifying the PS1 environment variable is only used to show a different prompt while you are in the container's network namespace.

Now you can use ping, netstat, ifconfig, ip, etc, given that they are installed on the host.

container# ping <IP>
container# ip route get <IP>
....
container# exit

Keep in mind that this only changes the network namespace, the mount namespace (file system) has not changed and therefore name resolving may not work correctly (it's still using the /etc/hosts file on the host)

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