| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| errors | Package errors implements functions to manipulate errors. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/docker/distribution/registry/client | |
| github.com/docker/distribution/registry/client/auth/challenge | |
| github.com/docker/distribution/registry/client/transport | |
| net/http | Package http provides HTTP client and server implementations. |
| net/url | Package url parses URLs and implements query escaping. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |