To run a simple "hello-world" container, one needs to set the args parameter in the spec to call hello.
This can be done using sed(1), jq(1), or a text editor.
The following commands will:
- create a bundle for hello-world;
- change the command to run in a container to /hello using jq(1);
- run the hello command in a new hello-world container named container1.
mkdir hello
cd hello
docker pull hello-world
docker export $(docker create hello-world) > hello-world.tar
mkdir rootfs
tar -C rootfs -xf hello-world.tar
runc spec
jq '.process.args |= ["/hello"]' < config.json > new.json
mv -f new.json config.json
runc run container1
In the run command above, container1 is the name for the instance of the container that you are starting.
The name you provide for the container instance must be unique on your host.
An alternative for generating a customized spec config is to use oci-runtime-tool; its sub-command oci-runtime-toolgenerate has lots of options that can be used to do any customizations as you want. See
runtime-tools ⟨https://github.com/opencontainers/runtime-tools⟩ to get more information.
When starting a container through runc, the latter usually needs root privileges. If not already running
as root, you can use sudo(8), for example:
sudo runc start container1
Alternatively, you can start a rootless container, which has the ability to run without root privileges.
For this to work, the specification file needs to be adjusted accordingly. You can pass the --rootless
option to this command to generate a proper rootless spec file.