| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/docker/distribution/context | Package context provides several utilities for working with Go's context in http requests. |
| github.com/docker/distribution/reference | Package reference is deprecated, and has moved to github.com/distribution/reference. |
| github.com/docker/distribution/registry/storage/driver | |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |