This commit adds a number of limits to the Grafana flavor of the
Prometheus Rules API:
1. `limit` limits the maximum number of Rule Groups returned
2. `limit_rules` limits the maximum number of rules per Rule Group
3. `limit_alerts` limits the maximum number of alerts per rule
It sorts Rule Groups and rules within Rule Groups such that data in the
response is stable across requests. It also returns summaries (totals) for
all Rule Groups, individual Rule Groups and rules.
* pkg/web: closure-style middlewares
Switches the middleware execution model from web.Handlers in a slice to
web.Middleware.
Middlewares are temporarily kept in a slice to preserve ordering, but
prior to execution they are applied, forming a giant call-stack, giving
granular control over the execution flow.
* pkg/middleware: adapt to web.Middleware
* pkg/middleware/recovery: use c.Req over req
c.Req gets updated by future handlers, while req stays static.
The current recovery implementation needs this newer information
* pkg/web: correct middleware ordering
* pkg/webtest: adapt middleware
* pkg/web/hack: set w and r onto web.Context
By adopting std middlewares, it may happen they invoke next(w,r) without
putting their modified w,r into the web.Context, leading old-style
handlers to operate on outdated fields.
pkg/web now takes care of this
* pkg/middleware: selectively use future context
* pkg/web: accept closure-style on Use()
* webtest: Middleware testing
adds a utility function to web/webtest to obtain a http.ResponseWriter,
http.Request and http.Handler the same as a middleware that runs would receive
* *: cleanup
* pkg/web: don't wrap Middleware from Router
* pkg/web: require chain to write response
* *: remove temp files
* webtest: don't require chain write
* *: cleanup
* pkg/web: store http.Handler internally
* pkg/web: remove injection
Removes any injection code from pkg/web.
It already was no longer functional, as we already only injected into
`http.Handler`, meaning we only inject ctx.Req and ctx.Resp.
Any other types (*Context, *ReqContext) were already accessed using the
http.Request.Context.Value() method.
* *: remove type mappings
Removes any call to the previously removed TypeMapper, as those were
non-functional already.
* pkg/web: remove Context.Invoke
was no longer used outside of pkg/web and also no longer functional
It is conventionally common for the X-Forwarded-For header to contain a
comma-separated list of IP addresses, with each intermediate proxy
adding an additional item as a request passes through it. This change
makes the web framework handle this case appropriately, always selecting
the first item in the list.
