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-rw-r--r--modules/caddyhttp/reverseproxy/httptransport.go41
1 files changed, 40 insertions, 1 deletions
diff --git a/modules/caddyhttp/reverseproxy/httptransport.go b/modules/caddyhttp/reverseproxy/httptransport.go
index 327cc89..dce7b9e 100644
--- a/modules/caddyhttp/reverseproxy/httptransport.go
+++ b/modules/caddyhttp/reverseproxy/httptransport.go
@@ -21,6 +21,7 @@ import (
"encoding/base64"
"fmt"
"io/ioutil"
+ weakrand "math/rand"
"net"
"net/http"
"reflect"
@@ -43,6 +44,9 @@ type HTTPTransport struct {
// able to borrow/use at least some of these config fields; if so,
// maybe move them into a type called CommonTransport and embed it?
+ // Configures the DNS resolver used to resolve the IP address of upstream hostnames.
+ Resolver *UpstreamResolver `json:"resolver,omitempty"`
+
// Configures TLS to the upstream. Setting this to an empty struct
// is sufficient to enable TLS with reasonable defaults.
TLS *TLSConfig `json:"tls,omitempty"`
@@ -146,7 +150,30 @@ func (h *HTTPTransport) NewTransport(ctx caddy.Context) (*http.Transport, error)
dialer := &net.Dialer{
Timeout: time.Duration(h.DialTimeout),
FallbackDelay: time.Duration(h.FallbackDelay),
- // TODO: Resolver
+ }
+
+ if h.Resolver != nil {
+ for _, v := range h.Resolver.Addresses {
+ addr, err := caddy.ParseNetworkAddress(v)
+ if err != nil {
+ return nil, err
+ }
+ if addr.PortRangeSize() != 1 {
+ return nil, fmt.Errorf("resolver address must have exactly one address; cannot call %v", addr)
+ }
+ h.Resolver.netAddrs = append(h.Resolver.netAddrs, addr)
+ }
+ d := &net.Dialer{
+ Timeout: time.Duration(h.DialTimeout),
+ FallbackDelay: time.Duration(h.FallbackDelay),
+ }
+ dialer.Resolver = &net.Resolver{
+ PreferGo: true,
+ Dial: func(ctx context.Context, _, _ string) (net.Conn, error) {
+ addr := h.Resolver.netAddrs[weakrand.Intn(len(h.Resolver.netAddrs))]
+ return d.DialContext(ctx, addr.Network, addr.JoinHostPort(0))
+ },
+ }
}
rt := &http.Transport{
@@ -359,6 +386,18 @@ func (t TLSConfig) MakeTLSClientConfig(ctx caddy.Context) (*tls.Config, error) {
return cfg, nil
}
+// UpstreamResolver holds the set of addresses of DNS resolvers of
+// upstream addresses
+type UpstreamResolver struct {
+ // The addresses of DNS resolvers to use when looking up the addresses of proxy upstreams.
+ // It accepts [network addresses](/docs/conventions#network-addresses)
+ // with port range of only 1. If the host is an IP address, it will be dialed directly to resolve the upstream server.
+ // If the host is not an IP address, the addresses are resolved using the [name resolution convention](https://golang.org/pkg/net/#hdr-Name_Resolution) of the Go standard library.
+ // If the array contains more than 1 resolver address, one is chosen at random.
+ Addresses []string `json:"addresses,omitempty"`
+ netAddrs []caddy.NetworkAddress
+}
+
// KeepAlive holds configuration pertaining to HTTP Keep-Alive.
type KeepAlive struct {
// Whether HTTP Keep-Alive is enabled. Default: true