OCI Registry As Storage

oras can push/pull any files to/from any registry with OCI image support.

Registries with known support:

• Distribution (open source, version 2.7+)
• Azure Container Registry

For more background on this topic, please see this post.

CLI

oras is a CLI that allows you to push and pull files from any registry with OCI image support.

Pushing files to remote registry

oras push localhost:5000/hello:latest hi.txt

The default media type for all files is application/vnd.oci.image.layer.v1.tar.

The push a custom media type, use the format filename[:type]:

oras push localhost:5000/hello:latest hi.txt:application/vnd.me.hi

To push multiple files with different media types:

oras push localhost:5000/hello:latest hi.txt:application/vnd.me.hi bye.txt:application/vnd.me.bye

Pulling files from remote registry

oras pull localhost:5000/hello:latest

By default, only blobs with media type application/vnd.oci.image.layer.v1.tar will be downloaded.

To specify which media types to download, use the --media-type/-t flag:

oras pull localhost:5000/hello:latest -t application/vnd.me.hi

Or to allow all media types, use the --allow-all/-a flag:

oras pull localhost:5000/hello:latest -a

Login Credentials

oras uses the local docker credential by default. Please run docker login in advance for any private registries.

oras also accepts explicit credentials via options. For example,

oras pull -u username -p password myregistry.io/myimage:latest

Run in Docker

Public image is available on Docker Hub at ocistorage/oras

Run on Mac/Linux

docker run --rm -it -v $(pwd):/workplace ocistorage/oras:v0.3.0 \
  pull myregistry.io/hello:latest

Run on Windows PowerShell

docker run --rm -it -v ${pwd}:/workplace ocistorage/oras:v0.3.0 \
  pull myregistry.io/hello:latest

Run on Windows Commands

docker run --rm -it -v %cd%:/workplace ocistorage/oras:v0.3.0 \
  pull myregistry.io/hello:latest

Install the binary

Install from latest release (v0.3.0):

# on Linux
curl -LO https://github.com/shizhMSFT/oras/releases/download/v0.3.0/oras_0.3.0_linux_amd64.tar.gz

# on macOS
curl -LO https://github.com/shizhMSFT/oras/releases/download/v0.3.0/oras_0.3.0_darwin_amd64.tar.gz

# on Windows
curl -LO https://github.com/shizhMSFT/oras/releases/download/v0.3.0/oras_0.3.0_windows_amd64.tar.gz

mkdir -p oras/
tar -zxf oras_0.3.0_*.tar.gz -C oras/
mv oras/bin/oras /usr/local/bin/
rm -rf oras_0.3.0_*.tar.gz oras/

Then, to run:

oras help

The checksums for the .tar.gz files above can be found here.

Go Module

The package github.com/shizhMSFT/oras/pkg/oras can quickly be imported in other Go-based tools that wish to benefit from the ability to store arbitrary content in container registries.

Example:

Source

package main

import (
	"context"
	"fmt"

	"github.com/containerd/containerd/remotes/docker"
	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
	"github.com/shizhMSFT/oras/pkg/content"
	"github.com/shizhMSFT/oras/pkg/oras"
)

func check(e error) {
	if e != nil {
		panic(e)
	}
}

func main() {
	ref := "localhost:5000/oras:test"
	fileName := "hello.txt"
	fileContent := []byte("Hello World!\n")
	customMediaType := "my.custom.media.type"

	ctx := context.Background()
	resolver := docker.NewResolver(docker.ResolverOptions{})

	// Push file(s) w custom mediatype to registry
	memoryStore := content.NewMemoryStore()
	desc := memoryStore.Add(fileName, customMediaType, fileContent)
	pushContents := []ocispec.Descriptor{desc}
	fmt.Printf("Pushing %s to %s... ", fileName, ref)
	err := oras.Push(ctx, resolver, ref, memoryStore, pushContents)
	check(err)
	fmt.Println("success!")

	// Pull file(s) from registry and save to disk
	fmt.Printf("Pulling from %s and saving to %s... ", ref, fileName)
	fileStore := content.NewFileStore("")
	allowedMediaTypes := []string{customMediaType}
	_, err = oras.Pull(ctx, resolver, ref, fileStore, allowedMediaTypes...)
	check(err)
	fmt.Println("success!")
	fmt.Printf("Try running 'cat %s'\n", fileName)
}