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Default to upstream to self (#2436)

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* Default to upstream to self

This is a backwards incompatible change.

This is a massive (cleanup) PR where we default to resolving external
names by the coredns process itself, instead of directly forwarding them
to some upstream.

This ignores any arguments `upstream` may have had and makes it depend
on proxy/forward configuration in the Corefile. This allows resolved
upstream names to be cached and we have better healthchecking of the
upstreams. It also means there is only one way to resolve names, by
either using the proxy or forward plugin.

The proxy/forward lookup.go functions have been removed. This also
lessen the dependency on proxy, meaning deprecating proxy will become
easier. Some tests have been removed as well, or moved to the top-level
test directory as they now require a full coredns process instead of
just the plugin.

For the etcd plugin, the entire StubZone resolving is *dropped*! This
was a hacky (but working) solution to say the least. If someone cares
deeply it can be brought back (maybe)?

The pkg/upstream is now very small and almost does nothing. Also the
New() function was changed to return a pointer to upstream.Upstream. It
also returns only one parameter, so any stragglers using it will
encounter a compile error.

All documentation has been adapted. This affected the following plugins:
* etcd
* file
* auto
* secondary
* federation
* template
* route53

A followup PR will make any upstream directives with arguments an error,
right now they are ignored.

Signed-off-by: Miek Gieben <miek@miek.nl>

* Fix etcd build - probably still fails unit test

Signed-off-by: Miek Gieben <miek@miek.nl>

* Slightly smarter lookup check in upstream

Signed-off-by: Miek Gieben <miek@miek.nl>

* Compilez

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2019-01-13 16:54:49 +00:00
committed by GitHub
parent 6b56a9c921
commit 9c16ed1d14
55 changed files with 184 additions and 1349 deletions
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69
plugin/forward/forward_test.go
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@@ -1,69 +0,0 @@
package forward
import (
"testing"
"github.com/coredns/coredns/plugin/pkg/dnstest"
"github.com/coredns/coredns/plugin/pkg/transport"
"github.com/coredns/coredns/plugin/test"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
func TestForward(t *testing.T) {
s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {
ret := new(dns.Msg)
ret.SetReply(r)
ret.Answer = append(ret.Answer, test.A("example.org. IN A 127.0.0.1"))
w.WriteMsg(ret)
})
defer s.Close()
p := NewProxy(s.Addr, transport.DNS)
f := New()
f.SetProxy(p)
defer f.Close()
state := request.Request{W: &test.ResponseWriter{}, Req: new(dns.Msg)}
state.Req.SetQuestion("example.org.", dns.TypeA)
resp, err := f.Forward(state)
if err != nil {
t.Fatal("Expected to receive reply, but didn't")
}
// expect answer section with A record in it
if len(resp.Answer) == 0 {
t.Fatalf("Expected to at least one RR in the answer section, got none: %s", resp)
}
if resp.Answer[0].Header().Rrtype != dns.TypeA {
t.Errorf("Expected RR to A, got: %d", resp.Answer[0].Header().Rrtype)
}
if resp.Answer[0].(*dns.A).A.String() != "127.0.0.1" {
t.Errorf("Expected 127.0.0.1, got: %s", resp.Answer[0].(*dns.A).A.String())
}
}
func TestForwardRefused(t *testing.T) {
s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {
ret := new(dns.Msg)
ret.SetReply(r)
ret.Rcode = dns.RcodeRefused
w.WriteMsg(ret)
})
defer s.Close()
p := NewProxy(s.Addr, transport.DNS)
f := New()
f.SetProxy(p)
defer f.Close()
state := request.Request{W: &test.ResponseWriter{}, Req: new(dns.Msg)}
state.Req.SetQuestion("example.org.", dns.TypeA)
resp, err := f.Forward(state)
if err != nil {
t.Fatal("Expected to receive reply, but didn't")
}
if resp.Rcode != dns.RcodeRefused {
t.Errorf("Expected rcode to be %d, got %d", dns.RcodeRefused, resp.Rcode)
}
}

89
plugin/forward/lookup.go
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@@ -1,89 +0,0 @@
// 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 opening a new connection for every client. It works with UDP and TCP and uses
// inband healthchecking.
package forward
import (
"context"
"github.com/coredns/coredns/plugin/pkg/transport"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
// 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
var upstreamErr error
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.opts)
upstreamErr = err
if err != nil {
if fails < len(f.proxies) {
continue
}
break
}
// Check if the reply is correct; if not return FormErr.
if !state.Match(ret) {
return state.ErrorMessage(dns.RcodeFormatError), nil
}
ret = state.Scrub(ret)
return ret, err
}
if upstreamErr != nil {
return nil, upstreamErr
}
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], transport.DNS)
f.SetProxy(p)
}
return f
}

43
plugin/forward/lookup_test.go
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@@ -1,43 +0,0 @@
package forward
import (
"testing"
"github.com/coredns/coredns/plugin/pkg/dnstest"
"github.com/coredns/coredns/plugin/pkg/transport"
"github.com/coredns/coredns/plugin/test"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
func TestLookup(t *testing.T) {
s := dnstest.NewServer(func(w dns.ResponseWriter, r *dns.Msg) {
ret := new(dns.Msg)
ret.SetReply(r)
ret.Answer = append(ret.Answer, test.A("example.org. IN A 127.0.0.1"))
w.WriteMsg(ret)
})
defer s.Close()
p := NewProxy(s.Addr, transport.DNS)
f := New()
f.SetProxy(p)
defer f.Close()
state := request.Request{W: &test.ResponseWriter{}, Req: new(dns.Msg)}
resp, err := f.Lookup(state, "example.org.", dns.TypeA)
if err != nil {
t.Fatal("Expected to receive reply, but didn't")
}
// expect answer section with A record in it
if len(resp.Answer) == 0 {
t.Fatalf("Expected to at least one RR in the answer section, got none: %s", resp)
}
if resp.Answer[0].Header().Rrtype != dns.TypeA {
t.Errorf("Expected RR to A, got: %d", resp.Answer[0].Header().Rrtype)
}
if resp.Answer[0].(*dns.A).A.String() != "127.0.0.1" {
t.Errorf("Expected 127.0.0.1, got: %s", resp.Answer[0].(*dns.A).A.String())
}
}