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reverse_proxy: Allow dynamic backends (closes #990 and #1539)

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This PR enables the use of placeholders in an upstream's Dial address.

A Dial address must represent precisely one socket after replacements.

See also #998 and #1639.
This commit is contained in:
Matthew Holt 2019-10-11 14:25:39 -06:00
parent 4aa3af4b78
commit 1e31be8de0
No known key found for this signature in database
GPG key ID: 2A349DD577D586A5
6 changed files with 114 additions and 136 deletions
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7
listeners.go
View file

@ -286,9 +286,10 @@ func JoinNetworkAddress(network, host, port string) string {
if network != "" {
a = network + "/"
}
a += host
if port != "" {
a += ":" + port
if host != "" && port == "" {
a += host
} else if port != "" {
a += net.JoinHostPort(host, port)
}
return a
}

4
listeners_test.go
View file

@ -138,6 +138,10 @@ func TestJoinNetworkAddress(t *testing.T) {
network: "unix", host: "/foo/bar", port: "",
expect: "unix//foo/bar",
},
{
network: "", host: "::1", port: "1234",
expect: "[::1]:1234",
},
} {
actual := JoinNetworkAddress(tc.network, tc.host, tc.port)
if actual != tc.expect {

10
modules/caddyhttp/reverseproxy/caddyfile.go
View file

@ -81,9 +81,7 @@ func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
for d.Next() {
for _, up := range d.RemainingArgs() {
h.Upstreams = append(h.Upstreams, &Upstream{
Dial: up,
})
h.Upstreams = append(h.Upstreams, &Upstream{Dial: up})
}
for d.NextBlock(0) {
@ -94,9 +92,7 @@ func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
return d.ArgErr()
}
for _, up := range args {
h.Upstreams = append(h.Upstreams, &Upstream{
Dial: up,
})
h.Upstreams = append(h.Upstreams, &Upstream{Dial: up})
}
case "lb_policy":
@ -502,6 +498,7 @@ func (h *HTTPTransport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
if d.Val() == "off" {
var disable bool
h.KeepAlive.Enabled = &disable
break
}
dur, err := time.ParseDuration(d.Val())
if err != nil {
@ -521,6 +518,7 @@ func (h *HTTPTransport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
h.KeepAlive = new(KeepAlive)
}
h.KeepAlive.MaxIdleConns = num
h.KeepAlive.MaxIdleConnsPerHost = num
default:
return d.Errf("unrecognized subdirective %s", d.Val())

6
modules/caddyhttp/reverseproxy/healthchecks.go
View file

@ -115,7 +115,7 @@ func (h *Handler) doActiveHealthChecksForAllHosts() {
// so use a fake Host value instead; unix sockets are usually local
hostAddr = "localhost"
}
err = h.doActiveHealthCheck(NewDialInfo(network, addrs[0]), hostAddr, host)
err = h.doActiveHealthCheck(DialInfo{Network: network, Address: addrs[0]}, hostAddr, host)
if err != nil {
log.Printf("[ERROR] reverse_proxy: active health check for host %s: %v", networkAddr, err)
}
@ -259,7 +259,7 @@ func (h *Handler) countFailure(upstream *Upstream) {
err := upstream.Host.CountFail(1)
if err != nil {
log.Printf("[ERROR] proxy: upstream %s: counting failure: %v",
upstream.dialInfo, err)
upstream.Dial, err)
}
// forget it later
@ -268,7 +268,7 @@ func (h *Handler) countFailure(upstream *Upstream) {
err := host.CountFail(-1)
if err != nil {
log.Printf("[ERROR] proxy: upstream %s: expiring failure: %v",
upstream.dialInfo, err)
upstream.Dial, err)
}
}(upstream.Host, failDuration)
}

62
modules/caddyhttp/reverseproxy/hosts.go
View file

@ -72,7 +72,6 @@ type Upstream struct {
healthCheckPolicy *PassiveHealthChecks
cb CircuitBreaker
dialInfo DialInfo
}
// Available returns true if the remote host
@ -149,8 +148,7 @@ func (uh *upstreamHost) CountFail(delta int) error {
}
// SetHealthy sets the upstream has healthy or unhealthy
// and returns true if the value was different from before,
// or an error if the adjustment failed.
// and returns true if the new value is different.
func (uh *upstreamHost) SetHealthy(healthy bool) (bool, error) {
var unhealthy, compare int32 = 1, 0
if healthy {
@ -167,8 +165,12 @@ func (uh *upstreamHost) SetHealthy(healthy bool) (bool, error) {
// a host that can be represented in a URL, but
// they certainly have a network name and address).
type DialInfo struct {
// The network to use. This should be one of the
// values that is accepted by net.Dial:
// Upstream is the Upstream associated with
// this DialInfo. It may be nil.
Upstream *Upstream
// The network to use. This should be one of
// the values that is accepted by net.Dial:
// https://golang.org/pkg/net/#Dial
Network string
@ -176,33 +178,43 @@ type DialInfo struct {
// semantics and rules as net.Dial.
Address string
// Host and Port are components of Address,
// pre-split for convenience.
// Host and Port are components of Address.
Host, Port string
}
// NewDialInfo creates and populates a DialInfo
// for the given network and address. It splits
// the address into host and port values if the
// network type supports them, or uses the whole
// address as the port if splitting fails.
func NewDialInfo(network, address string) DialInfo {
var addrHost, addrPort string
if !strings.Contains(network, "unix") {
var err error
addrHost, addrPort, err = net.SplitHostPort(address)
if err != nil {
addrHost = address // assume there was no port
}
}
return DialInfo{network, address, addrHost, addrPort}
}
// String returns the Caddy network address form
// by joining the network and address with a
// forward slash.
func (di DialInfo) String() string {
return di.Network + "/" + di.Address
return caddy.JoinNetworkAddress(di.Network, di.Host, di.Port)
}
// fillDialInfo returns a filled DialInfo for the given upstream, using
// the given Replacer. Note that the returned value is not a pointer.
func fillDialInfo(upstream *Upstream, repl caddy.Replacer) (DialInfo, error) {
dial := repl.ReplaceAll(upstream.Dial, "")
netw, addrs, err := caddy.ParseNetworkAddress(dial)
if err != nil {
return DialInfo{}, fmt.Errorf("upstream %s: invalid dial address %s: %v", upstream.Dial, dial, err)
}
if len(addrs) != 1 {
return DialInfo{}, fmt.Errorf("upstream %s: dial address must represent precisely one socket: %s represents %d",
upstream.Dial, dial, len(addrs))
}
var dialHost, dialPort string
if !strings.Contains(netw, "unix") {
dialHost, dialPort, err = net.SplitHostPort(addrs[0])
if err != nil {
dialHost = addrs[0] // assume there was no port
}
}
return DialInfo{
Upstream: upstream,
Network: netw,
Address: addrs[0],
Host: dialHost,
Port: dialPort,
}, nil
}
// DialInfoCtxKey is used to store a DialInfo

161
modules/caddyhttp/reverseproxy/reverseproxy.go
View file

@ -87,6 +87,7 @@ func (h *Handler) Provision(ctx caddy.Context) error {
h.CBRaw = nil // allow GC to deallocate
}
// set up transport
if h.Transport == nil {
t := &HTTPTransport{
KeepAlive: &KeepAlive{
@ -102,6 +103,7 @@ func (h *Handler) Provision(ctx caddy.Context) error {
h.Transport = t
}
// set up load balancing
if h.LoadBalancing == nil {
h.LoadBalancing = new(LoadBalancing)
}
@ -152,85 +154,40 @@ func (h *Handler) Provision(ctx caddy.Context) error {
go h.activeHealthChecker()
}
var allUpstreams []*Upstream
// set up upstreams
for _, upstream := range h.Upstreams {
// if a port was not specified (and the network type uses
// ports), then maybe we can figure out the default port
netw, host, port, err := caddy.SplitNetworkAddress(upstream.Dial)
if err != nil && port == "" && !strings.Contains(netw, "unix") {
if host == "" {
// assume all that was given was the host, no port
host = upstream.Dial
}
// a port was not specified, but we may be able to
// infer it if we know the standard ports on which
// the transport protocol operates
if ht, ok := h.Transport.(*HTTPTransport); ok {
defaultPort := "80"
if ht.TLS != nil {
defaultPort = "443"
}
upstream.Dial = caddy.JoinNetworkAddress(netw, host, defaultPort)
}
// create or get the host representation for this upstream
var host Host = new(upstreamHost)
existingHost, loaded := hosts.LoadOrStore(upstream.Dial, host)
if loaded {
host = existingHost.(Host)
}
upstream.Host = host
// give it the circuit breaker, if any
upstream.cb = h.CB
// if the passive health checker has a non-zero UnhealthyRequestCount
// but the upstream has no MaxRequests set (they are the same thing,
// but the passive health checker is a default value for for upstreams
// without MaxRequests), copy the value into this upstream, since the
// value in the upstream (MaxRequests) is what is used during
// availability checks
if h.HealthChecks != nil &&
h.HealthChecks.Passive != nil &&
h.HealthChecks.Passive.UnhealthyRequestCount > 0 &&
upstream.MaxRequests == 0 {
upstream.MaxRequests = h.HealthChecks.Passive.UnhealthyRequestCount
}
// upstreams are allowed to map to only a single host,
// but an upstream's address may semantically represent
// multiple addresses, so make sure to handle each
// one in turn based on this one upstream config
network, addresses, err := caddy.ParseNetworkAddress(upstream.Dial)
if err != nil {
return fmt.Errorf("parsing dial address: %v", err)
}
for _, addr := range addresses {
// make a new upstream based on the original
// that has a singular dial address
upstreamCopy := *upstream
upstreamCopy.dialInfo = NewDialInfo(network, addr)
upstreamCopy.Dial = upstreamCopy.dialInfo.String()
upstreamCopy.cb = h.CB
// if host already exists from a current config,
// use that instead; otherwise, add it
// TODO: make hosts modular, so that their state can be distributed in enterprise for example
// TODO: If distributed, the pool should be stored in storage...
var host Host = new(upstreamHost)
activeHost, loaded := hosts.LoadOrStore(upstreamCopy.dialInfo.String(), host)
if loaded {
host = activeHost.(Host)
}
upstreamCopy.Host = host
// if the passive health checker has a non-zero "unhealthy
// request count" but the upstream has no MaxRequests set
// (they are the same thing, but one is a default value for
// for upstreams with a zero MaxRequests), copy the default
// value into this upstream, since the value in the upstream
// (MaxRequests) is what is used during availability checks
if h.HealthChecks != nil &&
h.HealthChecks.Passive != nil &&
h.HealthChecks.Passive.UnhealthyRequestCount > 0 &&
upstreamCopy.MaxRequests == 0 {
upstreamCopy.MaxRequests = h.HealthChecks.Passive.UnhealthyRequestCount
}
// upstreams need independent access to the passive
// health check policy because they run outside of the
// scope of a request handler
if h.HealthChecks != nil {
upstreamCopy.healthCheckPolicy = h.HealthChecks.Passive
}
allUpstreams = append(allUpstreams, &upstreamCopy)
// upstreams need independent access to the passive
// health check policy because passive health checks
// run without access to h.
if h.HealthChecks != nil {
upstream.healthCheckPolicy = h.HealthChecks.Passive
}
}
// replace the unmarshaled upstreams (possible 1:many
// address mapping) with our list, which is mapped 1:1,
// thus may have expanded the original list
h.Upstreams = allUpstreams
return nil
}
@ -247,7 +204,7 @@ func (h *Handler) Cleanup() error {
// remove hosts from our config from the pool
for _, upstream := range h.Upstreams {
hosts.Delete(upstream.dialInfo.String())
hosts.Delete(upstream.Dial)
}
return nil
@ -284,17 +241,25 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht
continue
}
// the dial address may vary per-request if placeholders are
// used, so perform those replacements here; the resulting
// DialInfo struct should have valid network address syntax
dialInfo, err := fillDialInfo(upstream, repl)
if err != nil {
return fmt.Errorf("making dial info: %v", err)
}
// attach to the request information about how to dial the upstream;
// this is necessary because the information cannot be sufficiently
// or satisfactorily represented in a URL
ctx := context.WithValue(r.Context(), DialInfoCtxKey, upstream.dialInfo)
ctx := context.WithValue(r.Context(), DialInfoCtxKey, dialInfo)
r = r.WithContext(ctx)
// set placeholders with information about this upstream
repl.Set("http.handlers.reverse_proxy.upstream.address", upstream.dialInfo.String())
repl.Set("http.handlers.reverse_proxy.upstream.hostport", upstream.dialInfo.Address)
repl.Set("http.handlers.reverse_proxy.upstream.host", upstream.dialInfo.Host)
repl.Set("http.handlers.reverse_proxy.upstream.port", upstream.dialInfo.Port)
repl.Set("http.handlers.reverse_proxy.upstream.address", dialInfo.String())
repl.Set("http.handlers.reverse_proxy.upstream.hostport", dialInfo.Address)
repl.Set("http.handlers.reverse_proxy.upstream.host", dialInfo.Host)
repl.Set("http.handlers.reverse_proxy.upstream.port", dialInfo.Port)
repl.Set("http.handlers.reverse_proxy.upstream.requests", strconv.Itoa(upstream.Host.NumRequests()))
repl.Set("http.handlers.reverse_proxy.upstream.max_requests", strconv.Itoa(upstream.MaxRequests))
repl.Set("http.handlers.reverse_proxy.upstream.fails", strconv.Itoa(upstream.Host.Fails()))
@ -311,7 +276,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht
}
// proxy the request to that upstream
proxyErr = h.reverseProxy(w, r, upstream)
proxyErr = h.reverseProxy(w, r, dialInfo)
if proxyErr == nil || proxyErr == context.Canceled {
// context.Canceled happens when the downstream client
// cancels the request, which is not our failure
@ -405,12 +370,12 @@ func (h Handler) prepareRequest(req *http.Request) error {
// reverseProxy performs a round-trip to the given backend and processes the response with the client.
// (This method is mostly the beginning of what was borrowed from the net/http/httputil package in the
// Go standard library which was used as the foundation.)
func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, upstream *Upstream) error {
upstream.Host.CountRequest(1)
defer upstream.Host.CountRequest(-1)
func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, di DialInfo) error {
di.Upstream.Host.CountRequest(1)
defer di.Upstream.Host.CountRequest(-1)
// point the request to this upstream
h.directRequest(req, upstream)
h.directRequest(req, di)
// do the round-trip
start := time.Now()
@ -421,8 +386,8 @@ func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, upstre
}
// update circuit breaker on current conditions
if upstream.cb != nil {
upstream.cb.RecordMetric(res.StatusCode, latency)
if di.Upstream.cb != nil {
di.Upstream.cb.RecordMetric(res.StatusCode, latency)
}
// perform passive health checks (if enabled)
@ -430,14 +395,14 @@ func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, upstre
// strike if the status code matches one that is "bad"
for _, badStatus := range h.HealthChecks.Passive.UnhealthyStatus {
if caddyhttp.StatusCodeMatches(res.StatusCode, badStatus) {
h.countFailure(upstream)
h.countFailure(di.Upstream)
}
}
// strike if the roundtrip took too long
if h.HealthChecks.Passive.UnhealthyLatency > 0 &&
latency >= time.Duration(h.HealthChecks.Passive.UnhealthyLatency) {
h.countFailure(upstream)
h.countFailure(di.Upstream)
}
}
@ -554,23 +519,21 @@ func (lb LoadBalancing) tryAgain(start time.Time, proxyErr error, req *http.Requ
return true
}
// directRequest modifies only req.URL so that it points to the
// given upstream host. It must modify ONLY the request URL.
func (h Handler) directRequest(req *http.Request, upstream *Upstream) {
// directRequest modifies only req.URL so that it points to the upstream
// in the given DialInfo. It must modify ONLY the request URL.
func (h Handler) directRequest(req *http.Request, di DialInfo) {
if req.URL.Host == "" {
// we need a host, so set the upstream's host address
fullHost := upstream.dialInfo.Address
reqHost := di.Address
// but if the port matches the scheme, strip the port because
// if the port equates to the scheme, strip the port because
// it's weird to make a request like http://example.com:80/.
host, port, err := net.SplitHostPort(fullHost)
if err == nil &&
(req.URL.Scheme == "http" && port == "80") ||
(req.URL.Scheme == "https" && port == "443") {
fullHost = host
if (req.URL.Scheme == "http" && di.Port == "80") ||
(req.URL.Scheme == "https" && di.Port == "443") {
reqHost = di.Host
}
req.URL.Host = fullHost
req.URL.Host = reqHost
}
}