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upstream.go
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upstream.go
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package proxy
import (
"io"
"io/ioutil"
"net/http"
"net/url"
"strconv"
"strings"
"time"
"github.com/mholt/caddy/config/parse"
)
var (
supportedPolicies map[string]func() Policy = make(map[string]func() Policy)
proxyHeaders http.Header = make(http.Header)
)
type staticUpstream struct {
from string
Hosts HostPool
Policy Policy
FailTimeout time.Duration
MaxFails int32
HealthCheck struct {
Path string
Interval time.Duration
}
}
// NewStaticUpstreams parses the configuration input and sets up
// static upstreams for the proxy middleware.
func NewStaticUpstreams(c parse.Dispenser) ([]Upstream, error) {
var upstreams []Upstream
for c.Next() {
upstream := &staticUpstream{
from: "",
Hosts: nil,
Policy: &Random{},
FailTimeout: 10 * time.Second,
MaxFails: 1,
}
if !c.Args(&upstream.from) {
return upstreams, c.ArgErr()
}
to := c.RemainingArgs()
if len(to) == 0 {
return upstreams, c.ArgErr()
}
for c.NextBlock() {
switch c.Val() {
case "policy":
if !c.NextArg() {
return upstreams, c.ArgErr()
}
if policyCreateFunc, ok := supportedPolicies[c.Val()]; ok {
upstream.Policy = policyCreateFunc()
} else {
return upstreams, c.ArgErr()
}
case "fail_timeout":
if !c.NextArg() {
return upstreams, c.ArgErr()
}
if dur, err := time.ParseDuration(c.Val()); err == nil {
upstream.FailTimeout = dur
} else {
return upstreams, err
}
case "max_fails":
if !c.NextArg() {
return upstreams, c.ArgErr()
}
if n, err := strconv.Atoi(c.Val()); err == nil {
upstream.MaxFails = int32(n)
} else {
return upstreams, err
}
case "health_check":
if !c.NextArg() {
return upstreams, c.ArgErr()
}
upstream.HealthCheck.Path = c.Val()
upstream.HealthCheck.Interval = 30 * time.Second
if c.NextArg() {
if dur, err := time.ParseDuration(c.Val()); err == nil {
upstream.HealthCheck.Interval = dur
} else {
return upstreams, err
}
}
case "proxy_header":
var header, value string
if !c.Args(&header, &value) {
return upstreams, c.ArgErr()
}
proxyHeaders.Add(header, value)
case "websocket":
proxyHeaders.Add("Connection", "{>Connection}")
proxyHeaders.Add("Upgrade", "{>Upgrade}")
}
}
upstream.Hosts = make([]*UpstreamHost, len(to))
for i, host := range to {
if !strings.HasPrefix(host, "http") {
host = "http://" + host
}
uh := &UpstreamHost{
Name: host,
Conns: 0,
Fails: 0,
FailTimeout: upstream.FailTimeout,
Unhealthy: false,
ExtraHeaders: proxyHeaders,
CheckDown: func(upstream *staticUpstream) UpstreamHostDownFunc {
return func(uh *UpstreamHost) bool {
if uh.Unhealthy {
return true
}
if uh.Fails >= upstream.MaxFails &&
upstream.MaxFails != 0 {
return true
}
return false
}
}(upstream),
}
if baseURL, err := url.Parse(uh.Name); err == nil {
uh.ReverseProxy = NewSingleHostReverseProxy(baseURL)
} else {
return upstreams, err
}
upstream.Hosts[i] = uh
}
if upstream.HealthCheck.Path != "" {
go upstream.HealthCheckWorker(nil)
}
upstreams = append(upstreams, upstream)
}
return upstreams, nil
}
// RegisterPolicy adds a custom policy to the proxy.
func RegisterPolicy(name string, policy func() Policy) {
supportedPolicies[name] = policy
}
func (u *staticUpstream) From() string {
return u.from
}
func (u *staticUpstream) healthCheck() {
for _, host := range u.Hosts {
hostURL := host.Name + u.HealthCheck.Path
if r, err := http.Get(hostURL); err == nil {
io.Copy(ioutil.Discard, r.Body)
r.Body.Close()
host.Unhealthy = r.StatusCode < 200 || r.StatusCode >= 400
} else {
host.Unhealthy = true
}
}
}
func (u *staticUpstream) HealthCheckWorker(stop chan struct{}) {
ticker := time.NewTicker(u.HealthCheck.Interval)
u.healthCheck()
for {
select {
case <-ticker.C:
u.healthCheck()
case <-stop:
// TODO: the library should provide a stop channel and global
// waitgroup to allow goroutines started by plugins a chance
// to clean themselves up.
}
}
}
func (u *staticUpstream) Select() *UpstreamHost {
pool := u.Hosts
if len(pool) == 1 {
if pool[0].Down() {
return nil
}
return pool[0]
}
allDown := true
for _, host := range pool {
if !host.Down() {
allDown = false
break
}
}
if allDown {
return nil
}
if u.Policy == nil {
return (&Random{}).Select(pool)
}
return u.Policy.Select(pool)
}