79 lines
3.9 KiB
Markdown
79 lines
3.9 KiB
Markdown
[](https://godoc.org/github.com/containers/image) [](https://travis-ci.org/containers/image)
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`image` is a set of Go libraries aimed at working in various way with
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containers' images and container image registries.
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The containers/image library allows application to pull and push images from
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container image registries, like the upstream docker registry. It also
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implements "simple image signing".
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The containers/image library also allows you to inspect a repository on a
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container registry without pulling down the image. This means it fetches the
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repository's manifest and it is able to show you a `docker inspect`-like json
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output about a whole repository or a tag. This library, in contrast to `docker
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inspect`, helps you gather useful information about a repository or a tag
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without requiring you to run `docker pull`.
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The containers/image library also allows you to translate from one image format
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to another, for example docker container images to OCI images. It also allows
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you to copy container images between various registries, possibly converting
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them as necessary, and to sign and verify images.
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## Command-line usage
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The containers/image project is only a library with no user interface;
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you can either incorporate it into your Go programs, or use the `skopeo` tool:
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The [skopeo](https://github.com/projectatomic/skopeo) tool uses the
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containers/image library and takes advantage of many of its features,
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e.g. `skopeo copy` exposes the `containers/image/copy.Image` functionality.
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## Dependencies
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This library does not ship a committed version of its dependencies in a `vendor`
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subdirectory. This is so you can make well-informed decisions about which
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libraries you should use with this package in your own projects, and because
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types defined in the `vendor` directory would be impossible to use from your projects.
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What this project tests against dependencies-wise is located
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[in vendor.conf](https://github.com/containers/image/blob/master/vendor.conf).
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## Building
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If you want to see what the library can do, or an example of how it is called,
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consider starting with the [skopeo](https://github.com/projectatomic/skopeo) tool
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instead.
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To integrate this library into your project, put it into `$GOPATH` or use
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your preferred vendoring tool to include a copy in your project.
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Ensure that the dependencies documented [in vendor.conf](https://github.com/containers/image/blob/master/vendor.conf)
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are also available
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(using those exact versions or different versions of your choosing).
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This library, by default, also depends on the GpgME and libostree C libraries. Either install them:
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```sh
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Fedora$ dnf install gpgme-devel libassuan-devel libostree-devel
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macOS$ brew install gpgme
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```
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or use the build tags described below to avoid the dependencies (e.g. using `go build -tags …`)
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### Supported build tags
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- `containers_image_openpgp`: Use a Golang-only OpenPGP implementation for signature verification instead of the default cgo/gpgme-based implementation;
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the primary downside is that creating new signatures with the Golang-only implementation is not supported.
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- `containers_image_ostree_stub`: Instead of importing `ostree:` transport in `github.com/containers/image/transports/alltransports`, use a stub which reports that the transport is not supported. This allows building the library without requiring the `libostree` development libraries. The `github.com/containers/image/ostree` package is completely disabled
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and impossible to import when this build tag is in use.
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## Contributing
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When developing this library, please use `make` (or `make … BUILDTAGS=…`) to take advantage of the tests and validation.
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## License
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ASL 2.0
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## Contact
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- Mailing list: [containers-dev](https://groups.google.com/forum/?hl=en#!forum/containers-dev)
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- IRC: #[container-projects](irc://irc.freenode.net:6667/#container-projects) on freenode.net
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