containerd/remotes/resolver.go
Stephen J Day c062a85782
content: cleanup service and interfaces
After implementing pull, a few changes are required to the content store
interface to make sure that the implementation works smoothly.
Specifically, we work to make sure the predeclaration path for digests
works the same between remote and local writers. Before, we were
hesitent to require the the size and digest up front, but it became
clear that having this provided significant benefit.

There are also several cleanups related to naming. We now call the
expected digest `Expected` consistently across the board and `Total` is
used to mark the expected size.

This whole effort comes together to provide a very smooth status
reporting workflow for image pull and push. This will be more obvious
when the bulk of pull code lands.

There are a few other changes to make `content.WriteBlob` more broadly
useful. In accordance with addition for predeclaring expected size when
getting a `Writer`, `WriteBlob` now supports this fully. It will also
resume downloads if provided an `io.Seeker` or `io.ReaderAt`. Coupled
with the `httpReadSeeker` from `docker/distribution`, we should only be
a lines of code away from resumable downloads.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2017-02-22 13:30:01 -08:00

19 lines
617 B
Go

package remotes
import "context"
// Resolver provides a remote based on a locator.
type Resolver interface {
// Resolve returns a remote from the locator.
//
// A locator is a scheme-less URI representing the remote. Structurally, it
// has a host and path. The "host" can be used to directly reference a
// specific host or be matched against a specific handler.
Resolve(ctx context.Context, locator string) (Fetcher, error)
}
type ResolverFunc func(context.Context, string) (Fetcher, error)
func (fn ResolverFunc) Resolve(ctx context.Context, locator string) (Fetcher, error) {
return fn(ctx, locator)
}