| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| 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/metrics | |
| github.com/docker/distribution/registry/storage/driver | |
| github.com/docker/go-metrics | |
| io | Package io provides basic interfaces to I/O primitives. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |