2015-01-30 14:52:18 +08:00
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// Package proxy is middleware that proxies requests.
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2015-01-30 13:05:36 +08:00
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package proxy
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2015-01-30 08:17:59 +08:00
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import (
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"errors"
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2015-01-30 08:17:59 +08:00
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"net/http"
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2015-02-03 14:41:35 +08:00
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"net/url"
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2015-05-03 13:20:36 +08:00
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"sync/atomic"
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"time"
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2015-05-05 01:04:17 +08:00
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"github.com/mholt/caddy/middleware"
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2015-01-30 08:17:59 +08:00
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)
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2015-06-08 08:49:17 +08:00
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var errUnreachable = errors.New("unreachable backend")
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2015-05-03 13:20:36 +08:00
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2015-04-12 07:24:47 +08:00
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// Proxy represents a middleware instance that can proxy requests.
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type Proxy struct {
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Next middleware.Handler
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Upstreams []Upstream
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}
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2015-05-25 08:58:17 +08:00
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// Upstream manages a pool of proxy upstream hosts. Select should return a
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// suitable upstream host, or nil if no such hosts are available.
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type Upstream interface {
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// The path this upstream host should be routed on
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From() string
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// Selects an upstream host to be routed to.
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Select() *UpstreamHost
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}
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// UpstreamHostDownFunc can be used to customize how Down behaves.
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type UpstreamHostDownFunc func(*UpstreamHost) bool
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// UpstreamHost represents a single proxy upstream
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type UpstreamHost struct {
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// The hostname of this upstream host
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Name string
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ReverseProxy *ReverseProxy
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Conns int64
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Fails int32
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FailTimeout time.Duration
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Unhealthy bool
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ExtraHeaders http.Header
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CheckDown UpstreamHostDownFunc
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WithoutPathPrefix string
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}
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// Down checks whether the upstream host is down or not.
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// Down will try to use uh.CheckDown first, and will fall
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// back to some default criteria if necessary.
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func (uh *UpstreamHost) Down() bool {
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if uh.CheckDown == nil {
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// Default settings
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return uh.Unhealthy || uh.Fails > 0
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}
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return uh.CheckDown(uh)
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}
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// ServeHTTP satisfies the middleware.Handler interface.
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func (p Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
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for _, upstream := range p.Upstreams {
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if middleware.Path(r.URL.Path).Matches(upstream.From()) {
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var replacer middleware.Replacer
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start := time.Now()
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requestHost := r.Host
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// Since Select() should give us "up" hosts, keep retrying
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// hosts until timeout (or until we get a nil host).
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for time.Now().Sub(start) < (60 * time.Second) {
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host := upstream.Select()
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if host == nil {
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return http.StatusBadGateway, errUnreachable
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}
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proxy := host.ReverseProxy
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r.Host = host.Name
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if baseURL, err := url.Parse(host.Name); err == nil {
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r.Host = baseURL.Host
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if proxy == nil {
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proxy = NewSingleHostReverseProxy(baseURL, host.WithoutPathPrefix)
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}
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} else if proxy == nil {
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return http.StatusInternalServerError, err
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}
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var extraHeaders http.Header
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if host.ExtraHeaders != nil {
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extraHeaders = make(http.Header)
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if replacer == nil {
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rHost := r.Host
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r.Host = requestHost
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replacer = middleware.NewReplacer(r, nil)
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r.Host = rHost
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}
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for header, values := range host.ExtraHeaders {
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for _, value := range values {
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extraHeaders.Add(header,
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replacer.Replace(value))
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if header == "Host" {
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r.Host = replacer.Replace(value)
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}
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}
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}
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}
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2015-02-03 14:41:35 +08:00
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atomic.AddInt64(&host.Conns, 1)
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backendErr := proxy.ServeHTTP(w, r, extraHeaders)
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atomic.AddInt64(&host.Conns, -1)
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if backendErr == nil {
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return 0, nil
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}
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timeout := host.FailTimeout
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if timeout == 0 {
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timeout = 10 * time.Second
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}
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atomic.AddInt32(&host.Fails, 1)
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go func(host *UpstreamHost, timeout time.Duration) {
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time.Sleep(timeout)
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atomic.AddInt32(&host.Fails, -1)
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}(host, timeout)
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}
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return http.StatusBadGateway, errUnreachable
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2015-04-12 07:24:47 +08:00
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}
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}
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2015-03-29 06:56:56 +08:00
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2015-05-03 13:20:36 +08:00
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return p.Next.ServeHTTP(w, r)
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2015-01-30 08:17:59 +08:00
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}
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