82e03e5c89
This patch overhauls how we use containers/storage to store images, dropping most of our own metadata in favor of facilities that are now provided by default by the storage library. Additionally: * storageImageDestination now caches blobs in a temporary directory until Commit() is called * storageImageDestination generates a barebones manifest if one isn't supplied before Commit() is called * storageImageDestination uses new APIs in containers/storage to look for a local layer with the same contents of a blob, making it better at noticing when a PutBlob() isn't necessary * storageImageDestination sets the creation date for the image if it can be determined during Commit() * storageImageDestination defaults to using the hex part of the digest of the image's configuration blob as an image's ID, making it better at catching re-pulls of the same image * storageImageDestination no longer discards names which have been set for an image when reusing an ID * storageImage now counts sizes of uncompressed data when determining image size * storageImage now counts the size of the configuration blob when computing an image's size * storageImage returns an updated image with the manifest listing uncompressed layer blobs * storageImageSource also returns such an updated manifest * storageImageSource now always returns uncompressed layers Test changes: * storage tests now always write an image manifest * the test for determining an image's size now actually writes the configuration blob that it later tries to read Signed-off-by: Nalin Dahyabhai <nalin@redhat.com> |
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| copy | ||
| directory | ||
| docker | ||
| docs | ||
| image | ||
| internal | ||
| manifest | ||
| oci | ||
| openshift | ||
| ostree | ||
| pkg | ||
| signature | ||
| storage | ||
| tarball | ||
| transports | ||
| types | ||
| version | ||
| .gitignore | ||
| .pullapprove.yml | ||
| .travis.Dockerfile | ||
| .travis.yml | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| MAINTAINERS | ||
| Makefile | ||
| README.md | ||
| doc.go | ||
| registries.conf | ||
| vendor.conf | ||
README.md
image is a set of Go libraries aimed at working in various way with
containers' images and container image registries.
The containers/image library allows application to pull and push images from container image registries, like the upstream docker registry. It also implements "simple image signing".
The containers/image library also allows you to inspect a repository on a
container registry without pulling down the image. This means it fetches the
repository's manifest and it is able to show you a docker inspect-like json
output about a whole repository or a tag. This library, in contrast to docker inspect, helps you gather useful information about a repository or a tag
without requiring you to run docker pull.
The containers/image library also allows you to translate from one image format to another, for example docker container images to OCI images. It also allows you to copy container images between various registries, possibly converting them as necessary, and to sign and verify images.
Command-line usage
The containers/image project is only a library with no user interface;
you can either incorporate it into your Go programs, or use the skopeo tool:
The skopeo tool uses the
containers/image library and takes advantage of many of its features,
e.g. skopeo copy exposes the containers/image/copy.Image functionality.
Dependencies
This library does not ship a committed version of its dependencies in a vendor
subdirectory. This is so you can make well-informed decisions about which
libraries you should use with this package in your own projects, and because
types defined in the vendor directory would be impossible to use from your projects.
What this project tests against dependencies-wise is located in vendor.conf.
Building
If you want to see what the library can do, or an example of how it is called, consider starting with the skopeo tool instead.
To integrate this library into your project, put it into $GOPATH or use
your preferred vendoring tool to include a copy in your project.
Ensure that the dependencies documented in vendor.conf
are also available
(using those exact versions or different versions of your choosing).
This library, by default, also depends on the GpgME and libostree C libraries. Either install them:
Fedora$ dnf install gpgme-devel libassuan-devel libostree-devel
macOS$ brew install gpgme
or use the build tags described below to avoid the dependencies (e.g. using go build -tags …)
Supported build tags
containers_image_openpgp: Use a Golang-only OpenPGP implementation for signature verification instead of the default cgo/gpgme-based implementation; the primary downside is that creating new signatures with the Golang-only implementation is not supported.containers_image_ostree_stub: Instead of importingostree:transport ingithub.com/containers/image/transports/alltransports, use a stub which reports that the transport is not supported. This allows building the library without requiring thelibostreedevelopment libraries. Thegithub.com/containers/image/ostreepackage is completely disabled and impossible to import when this build tag is in use.
Contributing
When developing this library, please use make (or make … BUILDTAGS=…) to take advantage of the tests and validation.
License
ASL 2.0
Contact
- Mailing list: containers-dev
- IRC: #container-projects on freenode.net