| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/coreos/etcd/pkg/proxy | |
| go.uber.org/zap | Package zap provides fast, structured, leveled logging. |
| net/http | Package http provides HTTP client and server implementations. |
| net/url | Package url parses URLs and implements query escaping. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| os/signal | Package signal implements access to incoming signals. |
| syscall | Package syscall contains an interface to the low-level operating system primitives. |
| time | Package time provides functionality for measuring and displaying time. |