docker-runc spec - create a new specification file
docker-runc spec [command options] [arguments...]
The spec command creates the new specification file named
"config.json" for the bundle.
The spec generated is just a starter file. Editing of the spec is required to
achieve desired results. For example, the newly generated spec includes an
args parameter that is initially set to call the "sh" command when
the container is started. Calling "sh" may work for an ubuntu
container or busybox, but will not work for containers that do not include the
To run docker's hello-world container one needs to set the args parameter in the
spec to call hello. This can be done using the sed command or a text editor.
The following commands create a bundle for hello-world, change the default
args parameter in the spec from "sh" to "/hello", then run
the hello command in a new hello-world container named container1:
docker pull hello-world
docker export $(docker create hello-world) > hello-world.tar
tar -C rootfs -xf hello-world.tar
sed -i 's;"sh";"/hello";' config.json
docker-runc start container1
In the start 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
"ocitools", the sub-command "ocitools generate" has lots
of options that can be used to do any customizations as you want, see ocitools
⟨https://github.com/opencontainers/ocitools⟩ to get more
When starting a container through docker-runc, docker-runc needs root privilege.
If not already running as root, you can use sudo to give docker-runc root
privilege. For example: "sudo docker-runc start container1" will
give docker-runc root privilege to start the container on your host.
--bundle value, -b value path to the root of the bundle directory