57 lines
2.4 KiB
Markdown
57 lines
2.4 KiB
Markdown
% runc-spec "8"
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# NAME
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runc spec - create a new specification file
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# SYNOPSIS
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runc spec [command options] [arguments...]
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# DESCRIPTION
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The spec command creates the new specification file named "config.json" for
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the bundle.
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The spec generated is just a starter file. Editing of the spec is required to
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achieve desired results. For example, the newly generated spec includes an args
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parameter that is initially set to call the "sh" command when the container is
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started. Calling "sh" may work for an ubuntu container or busybox, but will not
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work for containers that do not include the "sh" program.
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# EXAMPLE
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To run docker's hello-world container one needs to set the args parameter
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in the spec to call hello. This can be done using the sed command or a text
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editor. The following commands create a bundle for hello-world, change the
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default args parameter in the spec from "sh" to "/hello", then run the hello
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command in a new hello-world container named container1:
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mkdir hello
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cd hello
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docker pull hello-world
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docker export $(docker create hello-world) > hello-world.tar
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mkdir rootfs
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tar -C rootfs -xf hello-world.tar
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runc spec
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sed -i 's;"sh";"/hello";' config.json
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runc start container1
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In the start command above, "container1" is the name for the instance of the
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container that you are starting. The name you provide for the container instance
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must be unique on your host.
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An alternative for generating a customized spec config is to use "oci-runtime-tool", the
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sub-command "oci-runtime-tool generate" has lots of options that can be used to do any
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customizations as you want, see [runtime-tools](https://github.com/opencontainers/runtime-tools)
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to get more information.
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When starting a container through runc, runc needs root privilege. If not
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already running as root, you can use sudo to give runc root privilege. For
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example: "sudo runc start container1" will give runc root privilege to start the
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container on your host.
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Alternatively, you can start a rootless container, which has the ability to run without root privileges.
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For this to work, the specification file needs to be adjusted accordingly.
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You can pass the parameter **--rootless** to this command to generate a proper rootless spec file.
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# OPTIONS
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--bundle value, -b value path to the root of the bundle directory
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--rootless generate a configuration for a rootless container
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