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umoci modifies Open Container images
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umoci Release

Build Status License: Apache 2.0

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Status: Beta

umoci modifies Open Container images. Not a great name, but what are you going to do. It also is a cool way for people to "dip their toe" into OCI images ("umoci" also means "to dip" in Serbian).

umoci intends to be a complete manipulation tool for OCI images. In particular, it should be seen as a more end-user-focused version of the oci-image-tools provided by the OCI. The hope is that all of this tooling will eventually be merged with the upstream repository, so that it is always kept up-to-date by the Open Container Initiative community.

However, currently there is a lot of discussion about the new tooling going into the OCI image tools, and right now I need tooling that can abstract all of the internals of the OCI specification into a single CLI interface. The main purpose of this tool is to serve as example of what I would like to see in an oci-image tool.

If you wish to provide feedback or contribute, read the for this project to refresh your knowledge about how to submit good bug reports and patches. Information about how to submit responsible security disclosures is also provided.


We regularly publish new releases, with each release being given a unique identifying version number (as governed by Semantic Versioning (SemVer)). Information about previous releases including the list of new features, bug fixes and resolved security issues is available in the change log. You can get pre-built binaries and corresponding source code for each release from the releases page.


If you wish to build umoci from source, follow these steps to build in with golang.

go get -d
make install

Your umoci binary will be in $HOME/bin.


umoci has a subcommand-based command-line. For more detailed information, see the generated man pages (which you can build with make doc). You can also read through our quick start guide.

% umoci --help
   umoci - umoci modifies Open Container images

   umoci [global options] command [command options] [arguments...]


   Aleksa Sarai <>

     raw      advanced internal image tooling
     help, h  Shows a list of commands or help for one command

     config      modifies the image configuration of an OCI image
     unpack      unpacks a reference into an OCI runtime bundle
     repack      repacks an OCI runtime bundle into a reference
     new         creates a blank tagged OCI image
     tag         creates a new tag in an OCI image
     remove, rm  removes a tag from an OCI image
     stat        displays status information of an image manifest

     gc        garbage-collects an OCI image's blobs
     init      create a new OCI layout
     list, ls  lists the set of tags in an OCI image

   --verbose      alias for --log=info
   --log value    set the log level (debug, info, [warn], error, fatal) (default: "warn")
   --help, -h     show help
   --version, -v  print the version

In Progress

Currently umoci relies on several from-scratch implementations of existing PRs against upstream projects (or aliased vendor projects that include PRs merged that are not merged upstream). This is because currently upstream projects are simply not mature enough to be used. However, this is something that I'm working on fixing.


umoci is licensed under the terms of the Apache 2.0 license.

umoci: Umoci Modifies Open Containers' Images
Copyright (C) 2016, 2017 SUSE LLC.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.
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