rest/http helpers
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REST helpers and middleware Build Status Go Report Card Coverage Status godoc

Install and update

go get -u


AppInfo middleware

Adds info to every response header:

  • App-Name - application name
  • App-Version - application version
  • Org - organization
  • M-Host - host name from instance-level $MHOST env

Ping-Pong middleware

Responds with pong on GET /ping. Also responds to anything with /ping suffix, like /v2/ping

example for both:

> http GET

HTTP/1.1 200 OK
Date: Sun, 15 Jul 2018 19:40:31 GMT
Content-Type: text/plain
Content-Length: 4
Connection: keep-alive
App-Name: remark42
App-Version: master-ed92a0b-20180630-15:59:56
Org: Umputun


Logger middleware

Logs all info about request, including user, method, status code, response size, url, elapsed time, request body (optional). Can be customized by passing flags - LogNone, LogAll, LogUser and LogBody. Flags can be combined (provided multiple times)

Recoverer middleware

Recoverer is a middleware that recovers from panics, logs the panic (and a backtrace), and returns a HTTP 500 (Internal Server Error) status if possible.

OnlyFrom middleware

OnlyFrom middleware allows access for limited list of source IPs. Such IPs can be defined as complete ip (like, prefix (129.168.) or CIDR (

Metrics middleware

Metrics middleware responds to GET /metrics with list of expvar. Optionally allows to restrict list of source ips.

BlackWords middleware

BlackWords middleware doesn't allow user-defined words in the request body.


  • rest.JSON - map alias, just for convenience type JSON map[string]interface{}
  • rest.RenderJSON - renders json response from interface{}
  • rest.RenderJSONFromBytes - renders json response from []byte
  • rest.RenderJSONWithHTML - renders json response with html tags and forced charset=utf-8
  • rest.SendErrorJSON - makes {error: blah, details: blah} json body and responds with given error code. Also adds context to logged message


Cache wrapper provides loading cache for rest/http responses. See cache readme for more details and examples.