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https://github.com/caddyserver/caddy.git
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d55d50b3b3
* reverse_proxy: ensure upstream address has port range of only 1 * reverse_proxy: don't log the error if upstream range size is more than 1
857 lines
28 KiB
Go
857 lines
28 KiB
Go
// Copyright 2015 Matthew Holt and The Caddy Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package reverseproxy
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"net"
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"net/http"
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"regexp"
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"strconv"
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"strings"
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"sync"
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"time"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/modules/caddyhttp"
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"github.com/caddyserver/caddy/v2/modules/caddyhttp/headers"
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"go.uber.org/zap"
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"golang.org/x/net/http/httpguts"
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)
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func init() {
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caddy.RegisterModule(Handler{})
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}
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// Handler implements a highly configurable and production-ready reverse proxy.
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//
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// Upon proxying, this module sets the following placeholders (which can be used
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// both within and after this handler):
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//
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// Placeholder | Description
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// ------------|-------------
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// `{http.reverse_proxy.upstream.address}` | The full address to the upstream as given in the config
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// `{http.reverse_proxy.upstream.hostport}` | The host:port of the upstream
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// `{http.reverse_proxy.upstream.host}` | The host of the upstream
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// `{http.reverse_proxy.upstream.port}` | The port of the upstream
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// `{http.reverse_proxy.upstream.requests}` | The approximate current number of requests to the upstream
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// `{http.reverse_proxy.upstream.max_requests}` | The maximum approximate number of requests allowed to the upstream
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// `{http.reverse_proxy.upstream.fails}` | The number of recent failed requests to the upstream
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type Handler struct {
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// Configures the method of transport for the proxy. A transport
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// is what performs the actual "round trip" to the backend.
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// The default transport is plaintext HTTP.
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TransportRaw json.RawMessage `json:"transport,omitempty" caddy:"namespace=http.reverse_proxy.transport inline_key=protocol"`
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// A circuit breaker may be used to relieve pressure on a backend
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// that is beginning to exhibit symptoms of stress or latency.
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// By default, there is no circuit breaker.
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CBRaw json.RawMessage `json:"circuit_breaker,omitempty" caddy:"namespace=http.reverse_proxy.circuit_breakers inline_key=type"`
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// Load balancing distributes load/requests between backends.
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LoadBalancing *LoadBalancing `json:"load_balancing,omitempty"`
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// Health checks update the status of backends, whether they are
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// up or down. Down backends will not be proxied to.
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HealthChecks *HealthChecks `json:"health_checks,omitempty"`
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// Upstreams is the list of backends to proxy to.
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Upstreams UpstreamPool `json:"upstreams,omitempty"`
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// Adjusts how often to flush the response buffer. A
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// negative value disables response buffering.
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// TODO: figure out good defaults and write docs for this
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// (see https://github.com/caddyserver/caddy/issues/1460)
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FlushInterval caddy.Duration `json:"flush_interval,omitempty"`
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// Headers manipulates headers between Caddy and the backend.
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// By default, all headers are passed-thru without changes,
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// with the exceptions of special hop-by-hop headers.
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//
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// X-Forwarded-For and X-Forwarded-Proto are also set
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// implicitly, but this may change in the future if the official
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// standardized Forwarded header field gains more adoption.
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Headers *headers.Handler `json:"headers,omitempty"`
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// If true, the entire request body will be read and buffered
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// in memory before being proxied to the backend. This should
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// be avoided if at all possible for performance reasons.
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BufferRequests bool `json:"buffer_requests,omitempty"`
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// List of handlers and their associated matchers to evaluate
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// after successful roundtrips. The first handler that matches
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// the response from a backend will be invoked. The response
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// body from the backend will not be written to the client;
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// it is up to the handler to finish handling the response.
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// If passive health checks are enabled, any errors from the
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// handler chain will not affect the health status of the
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// backend.
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//
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// Two new placeholders are available in this handler chain:
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// - `{http.reverse_proxy.status_code}` The status code
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// - `{http.reverse_proxy.status_text}` The status text
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HandleResponse []caddyhttp.ResponseHandler `json:"handle_response,omitempty"`
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Transport http.RoundTripper `json:"-"`
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CB CircuitBreaker `json:"-"`
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ctx caddy.Context
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logger *zap.Logger
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}
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// CaddyModule returns the Caddy module information.
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func (Handler) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.handlers.reverse_proxy",
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New: func() caddy.Module { return new(Handler) },
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}
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}
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// Provision ensures that h is set up properly before use.
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func (h *Handler) Provision(ctx caddy.Context) error {
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h.ctx = ctx
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h.logger = ctx.Logger(h)
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// start by loading modules
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if h.TransportRaw != nil {
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mod, err := ctx.LoadModule(h, "TransportRaw")
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if err != nil {
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return fmt.Errorf("loading transport: %v", err)
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}
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h.Transport = mod.(http.RoundTripper)
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}
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if h.LoadBalancing != nil && h.LoadBalancing.SelectionPolicyRaw != nil {
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mod, err := ctx.LoadModule(h.LoadBalancing, "SelectionPolicyRaw")
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if err != nil {
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return fmt.Errorf("loading load balancing selection policy: %s", err)
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}
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h.LoadBalancing.SelectionPolicy = mod.(Selector)
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}
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if h.CBRaw != nil {
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mod, err := ctx.LoadModule(h, "CBRaw")
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if err != nil {
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return fmt.Errorf("loading circuit breaker: %s", err)
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}
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h.CB = mod.(CircuitBreaker)
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}
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// ensure any embedded headers handler module gets provisioned
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// (see https://caddy.community/t/set-cookie-manipulation-in-reverse-proxy/7666?u=matt
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// for what happens if we forget to provision it)
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if h.Headers != nil {
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err := h.Headers.Provision(ctx)
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if err != nil {
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return fmt.Errorf("provisioning embedded headers handler: %v", err)
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}
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}
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// set up transport
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if h.Transport == nil {
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t := &HTTPTransport{
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KeepAlive: &KeepAlive{
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ProbeInterval: caddy.Duration(30 * time.Second),
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IdleConnTimeout: caddy.Duration(2 * time.Minute),
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MaxIdleConnsPerHost: 32,
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},
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DialTimeout: caddy.Duration(10 * time.Second),
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}
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err := t.Provision(ctx)
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if err != nil {
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return fmt.Errorf("provisioning default transport: %v", err)
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}
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h.Transport = t
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}
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// set up load balancing
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if h.LoadBalancing == nil {
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h.LoadBalancing = new(LoadBalancing)
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}
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if h.LoadBalancing.SelectionPolicy == nil {
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h.LoadBalancing.SelectionPolicy = RandomSelection{}
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}
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if h.LoadBalancing.TryDuration > 0 && h.LoadBalancing.TryInterval == 0 {
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// a non-zero try_duration with a zero try_interval
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// will always spin the CPU for try_duration if the
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// upstream is local or low-latency; avoid that by
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// defaulting to a sane wait period between attempts
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h.LoadBalancing.TryInterval = caddy.Duration(250 * time.Millisecond)
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}
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lbMatcherSets, err := ctx.LoadModule(h.LoadBalancing, "RetryMatchRaw")
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if err != nil {
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return err
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}
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err = h.LoadBalancing.RetryMatch.FromInterface(lbMatcherSets)
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if err != nil {
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return err
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}
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// set up upstreams
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for _, upstream := range h.Upstreams {
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addr, err := caddy.ParseNetworkAddress(upstream.Dial)
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if err != nil {
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return err
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}
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if addr.PortRangeSize() != 1 {
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return fmt.Errorf("multiple addresses (upstream must map to only one address): %v", addr)
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}
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// create or get the host representation for this upstream
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var host Host = new(upstreamHost)
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existingHost, loaded := hosts.LoadOrStore(upstream.String(), host)
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if loaded {
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host = existingHost.(Host)
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}
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upstream.Host = host
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// give it the circuit breaker, if any
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upstream.cb = h.CB
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// if the passive health checker has a non-zero UnhealthyRequestCount
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// but the upstream has no MaxRequests set (they are the same thing,
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// but the passive health checker is a default value for for upstreams
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// without MaxRequests), copy the value into this upstream, since the
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// value in the upstream (MaxRequests) is what is used during
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// availability checks
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if h.HealthChecks != nil && h.HealthChecks.Passive != nil {
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h.HealthChecks.Passive.logger = h.logger.Named("health_checker.passive")
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if h.HealthChecks.Passive.UnhealthyRequestCount > 0 &&
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upstream.MaxRequests == 0 {
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upstream.MaxRequests = h.HealthChecks.Passive.UnhealthyRequestCount
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}
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}
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// upstreams need independent access to the passive
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// health check policy because passive health checks
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// run without access to h.
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if h.HealthChecks != nil {
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upstream.healthCheckPolicy = h.HealthChecks.Passive
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}
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}
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if h.HealthChecks != nil {
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// set defaults on passive health checks, if necessary
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if h.HealthChecks.Passive != nil {
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if h.HealthChecks.Passive.FailDuration > 0 && h.HealthChecks.Passive.MaxFails == 0 {
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h.HealthChecks.Passive.MaxFails = 1
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}
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}
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// if active health checks are enabled, configure them and start a worker
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if h.HealthChecks.Active != nil &&
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(h.HealthChecks.Active.Path != "" || h.HealthChecks.Active.Port != 0) {
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h.HealthChecks.Active.logger = h.logger.Named("health_checker.active")
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timeout := time.Duration(h.HealthChecks.Active.Timeout)
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if timeout == 0 {
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timeout = 5 * time.Second
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}
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h.HealthChecks.Active.httpClient = &http.Client{
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Timeout: timeout,
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Transport: h.Transport,
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}
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if h.HealthChecks.Active.Interval == 0 {
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h.HealthChecks.Active.Interval = caddy.Duration(30 * time.Second)
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}
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if h.HealthChecks.Active.ExpectBody != "" {
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var err error
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h.HealthChecks.Active.bodyRegexp, err = regexp.Compile(h.HealthChecks.Active.ExpectBody)
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if err != nil {
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return fmt.Errorf("expect_body: compiling regular expression: %v", err)
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}
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}
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go h.activeHealthChecker()
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}
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}
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// set up any response routes
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for i, rh := range h.HandleResponse {
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err := rh.Provision(ctx)
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if err != nil {
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return fmt.Errorf("provisioning response handler %d: %v", i, err)
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}
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}
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return nil
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}
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// Cleanup cleans up the resources made by h during provisioning.
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func (h *Handler) Cleanup() error {
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// TODO: Close keepalive connections on reload? https://github.com/caddyserver/caddy/pull/2507/files#diff-70219fd88fe3f36834f474ce6537ed26R762
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// remove hosts from our config from the pool
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for _, upstream := range h.Upstreams {
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hosts.Delete(upstream.String())
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}
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return nil
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}
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func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
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repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
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// if enabled, buffer client request;
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// this should only be enabled if the
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// upstream requires it and does not
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// work with "slow clients" (gunicorn,
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// etc.) - this obviously has a perf
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// overhead and makes the proxy at
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// risk of exhausting memory and more
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// susceptible to slowloris attacks,
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// so it is strongly recommended to
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// only use this feature if absolutely
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// required, if read timeouts are set,
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// and if body size is limited
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if h.BufferRequests {
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buf := bufPool.Get().(*bytes.Buffer)
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buf.Reset()
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defer bufPool.Put(buf)
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io.Copy(buf, r.Body)
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r.Body.Close()
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r.Body = ioutil.NopCloser(buf)
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}
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// prepare the request for proxying; this is needed only once
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err := h.prepareRequest(r)
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if err != nil {
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return caddyhttp.Error(http.StatusInternalServerError,
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fmt.Errorf("preparing request for upstream round-trip: %v", err))
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}
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// we will need the original headers and Host value if
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// header operations are configured; and we should
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// restore them after we're done if they are changed
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// (for example, changing the outbound Host header
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// should not permanently change r.Host; issue #3509)
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reqHost := r.Host
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reqHeader := r.Header
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defer func() {
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r.Host = reqHost
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r.Header = reqHeader
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}()
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start := time.Now()
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var proxyErr error
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for {
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// choose an available upstream
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upstream := h.LoadBalancing.SelectionPolicy.Select(h.Upstreams, r)
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if upstream == nil {
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if proxyErr == nil {
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proxyErr = fmt.Errorf("no upstreams available")
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}
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if !h.LoadBalancing.tryAgain(h.ctx, start, proxyErr, r) {
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break
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}
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continue
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}
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// the dial address may vary per-request if placeholders are
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// used, so perform those replacements here; the resulting
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// DialInfo struct should have valid network address syntax
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dialInfo, err := upstream.fillDialInfo(r)
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if err != nil {
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return fmt.Errorf("making dial info: %v", err)
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}
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// attach to the request information about how to dial the upstream;
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// this is necessary because the information cannot be sufficiently
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// or satisfactorily represented in a URL
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caddyhttp.SetVar(r.Context(), dialInfoVarKey, dialInfo)
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// set placeholders with information about this upstream
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repl.Set("http.reverse_proxy.upstream.address", dialInfo.String())
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repl.Set("http.reverse_proxy.upstream.hostport", dialInfo.Address)
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repl.Set("http.reverse_proxy.upstream.host", dialInfo.Host)
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repl.Set("http.reverse_proxy.upstream.port", dialInfo.Port)
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repl.Set("http.reverse_proxy.upstream.requests", upstream.Host.NumRequests())
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repl.Set("http.reverse_proxy.upstream.max_requests", upstream.MaxRequests)
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repl.Set("http.reverse_proxy.upstream.fails", upstream.Host.Fails())
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// mutate request headers according to this upstream;
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// because we're in a retry loop, we have to copy
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// headers (and the r.Host value) from the original
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// so that each retry is identical to the first
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if h.Headers != nil && h.Headers.Request != nil {
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r.Header = make(http.Header)
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copyHeader(r.Header, reqHeader)
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r.Host = reqHost
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h.Headers.Request.ApplyToRequest(r)
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}
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// proxy the request to that upstream
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proxyErr = h.reverseProxy(w, r, dialInfo, next)
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if proxyErr == nil || proxyErr == context.Canceled {
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// context.Canceled happens when the downstream client
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// cancels the request, which is not our failure
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return nil
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}
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// if the roundtrip was successful, don't retry the request or
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// ding the health status of the upstream (an error can still
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// occur after the roundtrip if, for example, a response handler
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// after the roundtrip returns an error)
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if succ, ok := proxyErr.(roundtripSucceeded); ok {
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return succ.error
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}
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// remember this failure (if enabled)
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h.countFailure(upstream)
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// if we've tried long enough, break
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if !h.LoadBalancing.tryAgain(h.ctx, start, proxyErr, r) {
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break
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}
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}
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return caddyhttp.Error(http.StatusBadGateway, proxyErr)
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}
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// prepareRequest modifies req so that it is ready to be proxied,
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// except for directing to a specific upstream. This method mutates
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// headers and other necessary properties of the request and should
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// be done just once (before proxying) regardless of proxy retries.
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// This assumes that no mutations of the request are performed
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// by h during or after proxying.
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func (h Handler) prepareRequest(req *http.Request) error {
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// most of this is borrowed from the Go std lib reverse proxy
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if req.ContentLength == 0 {
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req.Body = nil // Issue golang/go#16036: nil Body for http.Transport retries
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}
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req.Close = false
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// if User-Agent is not set by client, then explicitly
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// disable it so it's not set to default value by std lib
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if _, ok := req.Header["User-Agent"]; !ok {
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req.Header.Set("User-Agent", "")
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}
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reqUpType := upgradeType(req.Header)
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removeConnectionHeaders(req.Header)
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// Remove hop-by-hop headers to the backend. Especially
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// important is "Connection" because we want a persistent
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// connection, regardless of what the client sent to us.
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for _, h := range hopHeaders {
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hv := req.Header.Get(h)
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if hv == "" {
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continue
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}
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if h == "Te" && hv == "trailers" {
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// Issue golang/go#21096: tell backend applications that
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// care about trailer support that we support
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// trailers. (We do, but we don't go out of
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// our way to advertise that unless the
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// incoming client request thought it was
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// worth mentioning)
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continue
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}
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req.Header.Del(h)
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}
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// After stripping all the hop-by-hop connection headers above, add back any
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// necessary for protocol upgrades, such as for websockets.
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if reqUpType != "" {
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req.Header.Set("Connection", "Upgrade")
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req.Header.Set("Upgrade", reqUpType)
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}
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if clientIP, _, err := net.SplitHostPort(req.RemoteAddr); err == nil {
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// If we aren't the first proxy retain prior
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// X-Forwarded-For information as a comma+space
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// separated list and fold multiple headers into one.
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if prior, ok := req.Header["X-Forwarded-For"]; ok {
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clientIP = strings.Join(prior, ", ") + ", " + clientIP
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}
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|
req.Header.Set("X-Forwarded-For", clientIP)
|
|
}
|
|
|
|
if req.Header.Get("X-Forwarded-Proto") == "" {
|
|
// set X-Forwarded-Proto; many backend apps expect this too
|
|
proto := "https"
|
|
if req.TLS == nil {
|
|
proto = "http"
|
|
}
|
|
req.Header.Set("X-Forwarded-Proto", proto)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// 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, di DialInfo, next caddyhttp.Handler) error {
|
|
di.Upstream.Host.CountRequest(1)
|
|
defer di.Upstream.Host.CountRequest(-1)
|
|
|
|
// point the request to this upstream
|
|
h.directRequest(req, di)
|
|
|
|
// do the round-trip; emit debug log with values we know are
|
|
// safe, or if there is no error, emit fuller log entry
|
|
start := time.Now()
|
|
res, err := h.Transport.RoundTrip(req)
|
|
duration := time.Since(start)
|
|
logger := h.logger.With(
|
|
zap.String("upstream", di.Upstream.String()),
|
|
zap.Object("request", caddyhttp.LoggableHTTPRequest{Request: req}),
|
|
zap.Duration("duration", duration))
|
|
if err != nil {
|
|
logger.Debug("upstream roundtrip", zap.Error(err))
|
|
return err
|
|
}
|
|
logger.Debug("upstream roundtrip",
|
|
zap.Object("headers", caddyhttp.LoggableHTTPHeader(res.Header)),
|
|
zap.Int("status", res.StatusCode))
|
|
|
|
// update circuit breaker on current conditions
|
|
if di.Upstream.cb != nil {
|
|
di.Upstream.cb.RecordMetric(res.StatusCode, duration)
|
|
}
|
|
|
|
// perform passive health checks (if enabled)
|
|
if h.HealthChecks != nil && h.HealthChecks.Passive != nil {
|
|
// 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(di.Upstream)
|
|
}
|
|
}
|
|
|
|
// strike if the roundtrip took too long
|
|
if h.HealthChecks.Passive.UnhealthyLatency > 0 &&
|
|
duration >= time.Duration(h.HealthChecks.Passive.UnhealthyLatency) {
|
|
h.countFailure(di.Upstream)
|
|
}
|
|
}
|
|
|
|
// see if any response handler is configured for this response from the backend
|
|
for i, rh := range h.HandleResponse {
|
|
if rh.Match != nil && !rh.Match.Match(res.StatusCode, res.Header) {
|
|
continue
|
|
}
|
|
|
|
repl := req.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
|
|
|
|
// if configured to only change the status code, do that then continue regular proxy response
|
|
if statusCodeStr := rh.StatusCode.String(); statusCodeStr != "" {
|
|
statusCode, err := strconv.Atoi(repl.ReplaceAll(statusCodeStr, ""))
|
|
if err != nil {
|
|
return caddyhttp.Error(http.StatusInternalServerError, err)
|
|
}
|
|
if statusCode != 0 {
|
|
res.StatusCode = statusCode
|
|
}
|
|
break
|
|
}
|
|
|
|
// otherwise, if there are any routes configured, execute those as the
|
|
// actual response instead of what we got from the proxy backend
|
|
if len(rh.Routes) == 0 {
|
|
continue
|
|
}
|
|
res.Body.Close()
|
|
repl.Set("http.reverse_proxy.status_code", res.StatusCode)
|
|
repl.Set("http.reverse_proxy.status_text", res.Status)
|
|
h.logger.Debug("handling response", zap.Int("handler", i))
|
|
if routeErr := rh.Routes.Compile(next).ServeHTTP(rw, req); routeErr != nil {
|
|
// wrap error in roundtripSucceeded so caller knows that
|
|
// the roundtrip was successful and to not retry
|
|
return roundtripSucceeded{routeErr}
|
|
}
|
|
}
|
|
|
|
// Deal with 101 Switching Protocols responses: (WebSocket, h2c, etc)
|
|
if res.StatusCode == http.StatusSwitchingProtocols {
|
|
h.handleUpgradeResponse(rw, req, res)
|
|
return nil
|
|
}
|
|
|
|
removeConnectionHeaders(res.Header)
|
|
|
|
for _, h := range hopHeaders {
|
|
res.Header.Del(h)
|
|
}
|
|
|
|
// apply any response header operations
|
|
if h.Headers != nil && h.Headers.Response != nil {
|
|
if h.Headers.Response.Require == nil ||
|
|
h.Headers.Response.Require.Match(res.StatusCode, res.Header) {
|
|
repl := req.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
|
|
h.Headers.Response.ApplyTo(res.Header, repl)
|
|
}
|
|
}
|
|
|
|
copyHeader(rw.Header(), res.Header)
|
|
|
|
// The "Trailer" header isn't included in the Transport's response,
|
|
// at least for *http.Transport. Build it up from Trailer.
|
|
announcedTrailers := len(res.Trailer)
|
|
if announcedTrailers > 0 {
|
|
trailerKeys := make([]string, 0, len(res.Trailer))
|
|
for k := range res.Trailer {
|
|
trailerKeys = append(trailerKeys, k)
|
|
}
|
|
rw.Header().Add("Trailer", strings.Join(trailerKeys, ", "))
|
|
}
|
|
|
|
rw.WriteHeader(res.StatusCode)
|
|
|
|
// some apps need the response headers before starting to stream content with http2,
|
|
// so it's important to explicitly flush the headers to the client before streaming the data.
|
|
// (see https://github.com/caddyserver/caddy/issues/3556 for use case and nuances)
|
|
if h.isBidirectionalStream(req, res) {
|
|
if wf, ok := rw.(http.Flusher); ok {
|
|
wf.Flush()
|
|
}
|
|
}
|
|
err = h.copyResponse(rw, res.Body, h.flushInterval(req, res))
|
|
res.Body.Close() // close now, instead of defer, to populate res.Trailer
|
|
if err != nil {
|
|
// we're streaming the response and we've already written headers, so
|
|
// there's nothing an error handler can do to recover at this point;
|
|
// the standard lib's proxy panics at this point, but we'll just log
|
|
// the error and abort the stream here
|
|
h.logger.Error("aborting with incomplete response", zap.Error(err))
|
|
return nil
|
|
}
|
|
|
|
if len(res.Trailer) > 0 {
|
|
// Force chunking if we saw a response trailer.
|
|
// This prevents net/http from calculating the length for short
|
|
// bodies and adding a Content-Length.
|
|
if fl, ok := rw.(http.Flusher); ok {
|
|
fl.Flush()
|
|
}
|
|
}
|
|
|
|
if len(res.Trailer) == announcedTrailers {
|
|
copyHeader(rw.Header(), res.Trailer)
|
|
return nil
|
|
}
|
|
|
|
for k, vv := range res.Trailer {
|
|
k = http.TrailerPrefix + k
|
|
for _, v := range vv {
|
|
rw.Header().Add(k, v)
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// tryAgain takes the time that the handler was initially invoked
|
|
// as well as any error currently obtained, and the request being
|
|
// tried, and returns true if another attempt should be made at
|
|
// proxying the request. If true is returned, it has already blocked
|
|
// long enough before the next retry (i.e. no more sleeping is
|
|
// needed). If false is returned, the handler should stop trying to
|
|
// proxy the request.
|
|
func (lb LoadBalancing) tryAgain(ctx caddy.Context, start time.Time, proxyErr error, req *http.Request) bool {
|
|
// if we've tried long enough, break
|
|
if time.Since(start) >= time.Duration(lb.TryDuration) {
|
|
return false
|
|
}
|
|
|
|
// if the error occurred while dialing (i.e. a connection
|
|
// could not even be established to the upstream), then it
|
|
// should be safe to retry, since without a connection, no
|
|
// HTTP request can be transmitted; but if the error is not
|
|
// specifically a dialer error, we need to be careful
|
|
if _, ok := proxyErr.(DialError); proxyErr != nil && !ok {
|
|
// if the error occurred after a connection was established,
|
|
// we have to assume the upstream received the request, and
|
|
// retries need to be carefully decided, because some requests
|
|
// are not idempotent
|
|
if lb.RetryMatch == nil && req.Method != "GET" {
|
|
// by default, don't retry requests if they aren't GET
|
|
return false
|
|
}
|
|
if !lb.RetryMatch.AnyMatch(req) {
|
|
return false
|
|
}
|
|
}
|
|
|
|
// otherwise, wait and try the next available host
|
|
select {
|
|
case <-time.After(time.Duration(lb.TryInterval)):
|
|
return true
|
|
case <-ctx.Done():
|
|
return false
|
|
}
|
|
}
|
|
|
|
// 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) {
|
|
// we need a host, so set the upstream's host address
|
|
reqHost := di.Address
|
|
|
|
// if the port equates to the scheme, strip the port because
|
|
// it's weird to make a request like http://example.com:80/.
|
|
if (req.URL.Scheme == "http" && di.Port == "80") ||
|
|
(req.URL.Scheme == "https" && di.Port == "443") {
|
|
reqHost = di.Host
|
|
}
|
|
|
|
req.URL.Host = reqHost
|
|
}
|
|
|
|
func copyHeader(dst, src http.Header) {
|
|
for k, vv := range src {
|
|
for _, v := range vv {
|
|
dst.Add(k, v)
|
|
}
|
|
}
|
|
}
|
|
|
|
func cloneHeader(h http.Header) http.Header {
|
|
h2 := make(http.Header, len(h))
|
|
for k, vv := range h {
|
|
vv2 := make([]string, len(vv))
|
|
copy(vv2, vv)
|
|
h2[k] = vv2
|
|
}
|
|
return h2
|
|
}
|
|
|
|
func upgradeType(h http.Header) string {
|
|
if !httpguts.HeaderValuesContainsToken(h["Connection"], "Upgrade") {
|
|
return ""
|
|
}
|
|
return strings.ToLower(h.Get("Upgrade"))
|
|
}
|
|
|
|
func singleJoiningSlash(a, b string) string {
|
|
aslash := strings.HasSuffix(a, "/")
|
|
bslash := strings.HasPrefix(b, "/")
|
|
switch {
|
|
case aslash && bslash:
|
|
return a + b[1:]
|
|
case !aslash && !bslash:
|
|
return a + "/" + b
|
|
}
|
|
return a + b
|
|
}
|
|
|
|
// removeConnectionHeaders removes hop-by-hop headers listed in the "Connection" header of h.
|
|
// See RFC 7230, section 6.1
|
|
func removeConnectionHeaders(h http.Header) {
|
|
if c := h.Get("Connection"); c != "" {
|
|
for _, f := range strings.Split(c, ",") {
|
|
if f = strings.TrimSpace(f); f != "" {
|
|
h.Del(f)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// LoadBalancing has parameters related to load balancing.
|
|
type LoadBalancing struct {
|
|
// A selection policy is how to choose an available backend.
|
|
// The default policy is random selection.
|
|
SelectionPolicyRaw json.RawMessage `json:"selection_policy,omitempty" caddy:"namespace=http.reverse_proxy.selection_policies inline_key=policy"`
|
|
|
|
// How long to try selecting available backends for each request
|
|
// if the next available host is down. By default, this retry is
|
|
// disabled. Clients will wait for up to this long while the load
|
|
// balancer tries to find an available upstream host.
|
|
TryDuration caddy.Duration `json:"try_duration,omitempty"`
|
|
|
|
// How long to wait between selecting the next host from the pool. Default
|
|
// is 250ms. Only relevant when a request to an upstream host fails. Be
|
|
// aware that setting this to 0 with a non-zero try_duration can cause the
|
|
// CPU to spin if all backends are down and latency is very low.
|
|
TryInterval caddy.Duration `json:"try_interval,omitempty"`
|
|
|
|
// A list of matcher sets that restricts with which requests retries are
|
|
// allowed. A request must match any of the given matcher sets in order
|
|
// to be retried if the connection to the upstream succeeded but the
|
|
// subsequent round-trip failed. If the connection to the upstream failed,
|
|
// a retry is always allowed. If unspecified, only GET requests will be
|
|
// allowed to be retried. Note that a retry is done with the next available
|
|
// host according to the load balancing policy.
|
|
RetryMatchRaw caddyhttp.RawMatcherSets `json:"retry_match,omitempty" caddy:"namespace=http.matchers"`
|
|
|
|
SelectionPolicy Selector `json:"-"`
|
|
RetryMatch caddyhttp.MatcherSets `json:"-"`
|
|
}
|
|
|
|
// Selector selects an available upstream from the pool.
|
|
type Selector interface {
|
|
Select(UpstreamPool, *http.Request) *Upstream
|
|
}
|
|
|
|
// Hop-by-hop headers. These are removed when sent to the backend.
|
|
// As of RFC 7230, hop-by-hop headers are required to appear in the
|
|
// Connection header field. These are the headers defined by the
|
|
// obsoleted RFC 2616 (section 13.5.1) and are used for backward
|
|
// compatibility.
|
|
var hopHeaders = []string{
|
|
"Alt-Svc",
|
|
"Connection",
|
|
"Proxy-Connection", // non-standard but still sent by libcurl and rejected by e.g. google
|
|
"Keep-Alive",
|
|
"Proxy-Authenticate",
|
|
"Proxy-Authorization",
|
|
"Te", // canonicalized version of "TE"
|
|
"Trailer", // not Trailers per URL above; https://www.rfc-editor.org/errata_search.php?eid=4522
|
|
"Transfer-Encoding",
|
|
"Upgrade",
|
|
}
|
|
|
|
// DialError is an error that specifically occurs
|
|
// in a call to Dial or DialContext.
|
|
type DialError struct{ error }
|
|
|
|
// TLSTransport is implemented by transports
|
|
// that are capable of using TLS.
|
|
type TLSTransport interface {
|
|
// TLSEnabled returns true if the transport
|
|
// has TLS enabled, false otherwise.
|
|
TLSEnabled() bool
|
|
|
|
// EnableTLS enables TLS within the transport
|
|
// if it is not already, using the provided
|
|
// value as a basis for the TLS config.
|
|
EnableTLS(base *TLSConfig) error
|
|
}
|
|
|
|
// roundtripSucceeded is an error type that is returned if the
|
|
// roundtrip succeeded, but an error occurred after-the-fact.
|
|
type roundtripSucceeded struct{ error }
|
|
|
|
var bufPool = sync.Pool{
|
|
New: func() interface{} {
|
|
return new(bytes.Buffer)
|
|
},
|
|
}
|
|
|
|
// Interface guards
|
|
var (
|
|
_ caddy.Provisioner = (*Handler)(nil)
|
|
_ caddy.CleanerUpper = (*Handler)(nil)
|
|
_ caddyhttp.MiddlewareHandler = (*Handler)(nil)
|
|
)
|