| expvar | Package expvar provides a standardized interface to public variables, such as operation counters in servers. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/codahale/hdrhistogram | |
| github.com/go-kit/kit/metrics | Package metrics provides a framework for application instrumentation. |
| github.com/prometheus/client_golang/prometheus | Package prometheus is the core instrumentation package. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| math | Package math provides basic constants and mathematical functions. |
| math/rand | Package rand implements pseudo-random number generators suitable for tasks such as simulation, but it should not be used for security-sensitive work. |
| net/http | Package http provides HTTP client and server implementations. |
| net/http/httptest | Package httptest provides utilities for HTTP testing. |
| regexp | Package regexp implements regular expression search. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| testing | Package testing provides support for automated testing of Go packages. |