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package core
import (
"github.com/miekg/coredns/core/https"
"github.com/miekg/coredns/core/parse"
"github.com/miekg/coredns/core/setup"
"github.com/miekg/coredns/middleware"
)
func init() {
// The parse package must know which directives
// are valid, but it must not import the setup
// or config package. To solve this problem, we
// fill up this map in our init function here.
// The parse package does not need to know the
// ordering of the directives.
for _, dir := range directiveOrder {
parse.ValidDirectives[dir.name] = struct{}{}
}
}
// Directives are registered in the order they should be
// executed. Middleware (directives that inject a handler)
// are executed in the order A-B-C-*-C-B-A, assuming
// they all call the Next handler in the chain.
//
// Ordering is VERY important. Every middleware will
// feel the effects of all other middleware below
// (after) them during a request, but they must not
// care what middleware above them are doing.
//
// For example, log needs to know the status code and
// exactly how many bytes were written to the client,
// which every other middleware can affect, so it gets
// registered first. The errors middleware does not
// care if gzip or log modifies its response, so it
// gets registered below them. Gzip, on the other hand,
// DOES care what errors does to the response since it
// must compress every output to the client, even error
// pages, so it must be registered before the errors
// middleware and any others that would write to the
// response.
var directiveOrder = []directive{
// Essential directives that initialize vital configuration settings
{"root", setup.Root},
{"bind", setup.BindHost},
{"tls", https.Setup},
{"health", setup.Health},
{"pprof", setup.PProf},
// Other directives that don't create HTTP handlers
{"startup", setup.Startup},
{"shutdown", setup.Shutdown},
// Directives that inject handlers (middleware)
{"prometheus", setup.Prometheus},
{"errors", setup.Errors},
{"log", setup.Log},
{"chaos", setup.Chaos},
{"rewrite", setup.Rewrite},
{"loadbalance", setup.Loadbalance},
{"cache", setup.Cache},
{"dnssec", setup.Dnssec},
{"file", setup.File},
{"secondary", setup.Secondary},
{"etcd", setup.Etcd},
{"kubernetes", setup.Kubernetes},
{"proxy", setup.Proxy},
}
// RegisterDirective adds the given directive to CoreDNS's list of directives.
// Pass the name of a directive you want it to be placed after,
// otherwise it will be placed at the bottom of the stack.
func RegisterDirective(name string, setup SetupFunc, after string) {
dir := directive{name: name, setup: setup}
idx := len(directiveOrder)
for i := range directiveOrder {
if directiveOrder[i].name == after {
idx = i + 1
break
}
}
newDirectives := append(directiveOrder[:idx], append([]directive{dir}, directiveOrder[idx:]...)...)
directiveOrder = newDirectives
parse.ValidDirectives[name] = struct{}{}
}
// directive ties together a directive name with its setup function.
type directive struct {
name string
setup SetupFunc
}
// SetupFunc takes a controller and may optionally return a middleware.
// If the resulting middleware is not nil, it will be chained into
// the DNS handlers in the order specified in this package.
type SetupFunc func(c *setup.Controller) (middleware.Middleware, error)
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