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reverseproxy: add support for custom DNS resolver (#3479)

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* reverse proxy: add support for custom resolver

* reverse proxy: don't pollute the global resolver with bootstrap resolver setup

* Improve documentation of reverseproxy.UpstreamResolver fields

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

* reverse proxy: clarify the name resolution conventions of upstream resolvers and bootstrap resolver

* remove support for bootstraper of resolver

* godoc and code-style changes

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>
This commit is contained in:
Mohammed Al Sahaf 2020-07-19 00:00:00 +03:00 committed by GitHub
parent 246a31aacd
commit bd9d796e6e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 40 additions and 1 deletions
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41
modules/caddyhttp/reverseproxy/httptransport.go
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@ -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