---
name: "umoci-raw-runtime-config"
section: "1"
platform: "linux"
package: "umoci"
version: "0.6.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/umoci-raw-runtime-config"
---

# umoci-raw-runtime-config(1)

Generate an OCI runtime configuration for an image

Aleksa Sarai DECEMBER 2016

## NAME

umoci raw runtime-config - Generate an OCI runtime configuration for an image

## SYNOPSIS

**umoci raw runtime-config** **--image**=*image*\[:*tag*\] \[**--rootfs**=*rootfs*\] \[**--rootless**\] *config*

**umoci raw config** **--image**=*image*\[:*tag*\] \[**--rootfs**=*rootfs*\] \[**--rootless**\] *config*

## DESCRIPTION

Generate a new OCI runtime configuration from an image, without extracting the rootfs of said image. The configuration is written to the path given by *config*, overwriting it if it exists already. This is one of the operations done by [**umoci-unpack**(1)](/umoci-unpack/1.md) when generating the runtime bundle, but because of the overhead of extracting a root filesystem, [**umoci-unpack**(1)](/umoci-unpack/1.md) is not practical to be used many times if the user doesn't actually want to use the root filesystem. Some fields require a root filesystem as a "source of truth", and a source root filesystem can be specified using **--rootfs**. The other flags have the same effects as with [**umoci-unpack**(1)](/umoci-unpack/1.md).

Note however that the output of [**umoci-raw-runtime-config**(1)](/umoci-raw-runtime-config/1.md) is not necessarily identical to the output from [**umoci-unpack**(1)](/umoci-unpack/1.md). This is especially true if **--rootfs** is not specified, which results in [**umoci**(1)](/umoci/1.md) leaving fields in the runtime spec to their defaults if computing their values would require using the root filesystem as a source-of-truth.

## OPTIONS

The global options are defined in [**umoci**(1)](/umoci/1.md).

**--image**=*image*\[:*tag*\]\
   The OCI image tag which will be extracted to the *bundle*. *image* must be a\
   path to a valid OCI image and *tag* must be a valid tag in the image. If\
   *tag* is not provided it defaults to "latest".

**--rootfs**=*rootfs*\
   Use *rootfs* as a secondary source of truth when generating the runtime\
   configuration (this is especially important for *Config.User* conversion). If\
   unspecified, any runtime fields that require a secondary source of truth to\
   be filled with be left in their default values. This may result in\
   discrepancies between the output of [**umoci-unpack**(1)](/umoci-unpack/1.md) and\
   [**umoci-raw-runtime-config**(1)](/umoci-raw-runtime-config/1.md).

**--rootless**\
   Generate a rootless container configuration, similar to the configuration\
   produced by [**umoci-unpack**(1)](/umoci-unpack/1.md) when provided the **--rootless** flag.

## EXAMPLE

The following downloads an image from a [**docker**(1)](/docker/1.md) registry using [**skopeo**(1)](/skopeo/1.md) and then generates the *config.json* for that image.

```
% skopeo copy docker://opensuse/amd64:42.2 oci:image:latest
% umoci raw runtime-config --image image:latest config.json
```

If a root filesystem is already present, it is possible to specify it with the **--rootfs** flag. This will source the root filesystem for conversion operations that necessitate it.

```
% skopeo copy docker://opensuse/amd64:42.2 oci:image:latest
# umoci unpack --image image bundle
% umoci raw runtime-config --image image --rootfs bundle/rootfs config.json
```

## SEE ALSO

[**umoci**(1)](/umoci/1.md), [**umoci-repack**(1)](/umoci-repack/1.md), [**runc**(8)](/runc/8.md)