I've got a Docker container running Ubuntu which I did as follows:

docker run -it ubuntu /bin/bash

however it doesn't seem to have ping. E.g.

bash: ping: command not found

Do I need to install that?

Seems a pretty basic command to be missing. I tried whereis ping which doesn't report anything.

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

apt-get update -y
apt-get install -y 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.