mirror of
https://github.com/coredns/coredns.git
synced 2025-10-31 02:03:20 -04:00
16504234e5
* plugin/forward: on demand healtchecking Only start doing health checks when we encouner an error (any error). This uses the new pluing/pkg/up package to abstract away the actual checking. This reduces the LOC quite a bit; does need more testing, unit testing and tcpdumping a bit. * fix tests * Fix readme * Use pkg/up for healthchecks * remove unused channel * more cleanups * update readme * * Again do go generate and go build; still referencing the wrong forward repo? Anyway fixed. * Use pkg/up for doing the healtchecks to cut back on unwanted queries * Change up.Func to return an error instead of a boolean. * Drop the string target argument as it doesn't make sense. * Add healthcheck test on failing to get an upstream answer. TODO(miek): double check Forward and Lookup and how they interact with HC, and if we correctly call close() on those * actual test * Tests here * more tests * try getting rid of host * Get rid of the host indirection * Finish removing hosts * moar testing * import fmt * field is not used * docs * move some stuff * bring back health_check * maxfails=0 test * git and merging, bah * review
74 lines
2.1 KiB
Go
74 lines
2.1 KiB
Go
// Package forward implements a forwarding proxy. It caches an upstream net.Conn for some time, so if the same
|
|
// client returns the upstream's Conn will be precached. Depending on how you benchmark this looks to be
|
|
// 50% faster than just openening a new connection for every client. It works with UDP and TCP and uses
|
|
// inband healthchecking.
|
|
package forward
|
|
|
|
import (
|
|
"github.com/coredns/coredns/request"
|
|
|
|
"github.com/miekg/dns"
|
|
"golang.org/x/net/context"
|
|
)
|
|
|
|
// Forward forward the request in state as-is. Unlike Lookup that adds EDNS0 suffix to the message.
|
|
// Forward may be called with a nil f, an error is returned in that case.
|
|
func (f *Forward) Forward(state request.Request) (*dns.Msg, error) {
|
|
if f == nil {
|
|
return nil, errNoForward
|
|
}
|
|
|
|
fails := 0
|
|
for _, proxy := range f.list() {
|
|
if proxy.Down(f.maxfails) {
|
|
fails++
|
|
if fails < len(f.proxies) {
|
|
continue
|
|
}
|
|
// All upstream proxies are dead, assume healtcheck is complete broken and randomly
|
|
// select an upstream to connect to.
|
|
proxy = f.list()[0]
|
|
}
|
|
|
|
ret, err := proxy.connect(context.Background(), state, f.forceTCP, true)
|
|
if err != nil {
|
|
if fails < len(f.proxies) {
|
|
continue
|
|
}
|
|
break
|
|
|
|
}
|
|
|
|
return ret, nil
|
|
}
|
|
return nil, errNoHealthy
|
|
}
|
|
|
|
// Lookup will use name and type to forge a new message and will send that upstream. It will
|
|
// set any EDNS0 options correctly so that downstream will be able to process the reply.
|
|
// Lookup may be called with a nil f, an error is returned in that case.
|
|
func (f *Forward) Lookup(state request.Request, name string, typ uint16) (*dns.Msg, error) {
|
|
if f == nil {
|
|
return nil, errNoForward
|
|
}
|
|
|
|
req := new(dns.Msg)
|
|
req.SetQuestion(name, typ)
|
|
state.SizeAndDo(req)
|
|
|
|
state2 := request.Request{W: state.W, Req: req}
|
|
|
|
return f.Forward(state2)
|
|
}
|
|
|
|
// NewLookup returns a Forward that can be used for plugin that need an upstream to resolve external names.
|
|
// Note that the caller must run Close on the forward to stop the health checking goroutines.
|
|
func NewLookup(addr []string) *Forward {
|
|
f := New()
|
|
for i := range addr {
|
|
p := NewProxy(addr[i], nil)
|
|
f.SetProxy(p)
|
|
}
|
|
return f
|
|
}
|