udistribution

Go library providing a client to interface with storage drivers of distribution/distribution without a listening HTTP server.

Develop in gitpod

Goal:

• Given a config and/or environment variables conforming to available configurations
  • a client interface can be initialized to access functions enabling access to methods in distribution api spec without a listening registry HTTP Server by exposing ServeHTTP method.

Making it easier for Go programs to consume APIs on a needed basis without a listening server. This approach maybe more secure in an environment where it is not practical to obtain TLS certificates from a trusted certificate authorities, such as an unpredictable hostname/ip address.

Current functionality:

• Modifies distribution/distribution to
  • Initialize client with config string and/or environment variables
  • ServeHTTP method can be accessed after initialization
• Implement a function to register new transport type to "github.com/containers/image/v5/transports"
  • Consumes distribution/distribution using exposed ServeHTTP method
  • End to end test which demonstrates how the transport type is registered and can be used to access distribution/distribution

Getting Started

Usage example as seen in test

	ut, err := udistribution.NewTransportFromNewConfig("", os.Environ())
	defer ut.Deregister()
	if err != nil {
		t.Errorf("failed to create transport with environment variables: %v", err)
	}
	srcRef, err := docker.ParseReference("//alpine")
	if err != nil {
		t.Errorf("failed to parse reference: %v", err)
	}
	destRef, err := ut.ParseReference("//alpine")
	if err != nil {
		t.Errorf("failed to parse reference: %v", err)
	}
	pc, err := getPolicyContext()
	if err != nil {
		t.Errorf("failed to get policy context: %v", err)
	}
	ctx, err := getDefaultContext()
	if err != nil {
		t.Errorf("failed to get default context: %v", err)
	}
	_, err = copy.Image(context.Background(), pc, destRef, srcRef, &copy.Options{
		SourceCtx:      ctx,
		DestinationCtx: ctx,
	})
	if err != nil {
		t.Errorf("%v", errors.Wrapf(err, "failed to copy image"))
	}

First you call NewClient with a config string and environment variables. Then you call the client's ServeHTTP method with a desired HTTP request.

You can use httptest.NewRecorder to record the response.

Alternatively, you may use alltransports.ParseImageName(ref) when transport name ut.Name():// is in the reference instead of using ut.ParseReference

Known issues:

Prometheus metrics config must be disabled.

NOTICE:

• This library contains some parts from distribution/distribution which is licensed under the Apache License 2.0.
  • Some parts has been modified to accommodate usage in this library.
  • A copy of the original distribution/distribution license is included in the repository at LICENSE