Provided by: runc_1.1.2-0ubuntu1_amd64 bug


       runc-spec - create a new specification file


       runc spec [option ...]


       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 sh binary.


       --bundle|-b path
              Set path to the root of the bundle directory.

              Generate  a  configuration  for  a rootless container. Note this option is entirely
              different from the global --rootless option.


       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

       An  alternative  for  generating  a customized spec config is to use oci-runtime-tool; its
       sub-command oci-runtime-tool generate has lots of options that  can  be  used  to  do  any
       customizations  as you want. See runtime-tools ⟨
       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.


       runc-run(8), runc(8).