133 lines
2.5 KiB
Go
133 lines
2.5 KiB
Go
/*
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Copyright 2014 CoreOS, Inc.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package proxy
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import (
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"log"
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"net/url"
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"sync"
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"time"
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)
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const (
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// amount of time an endpoint will be held in a failed
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// state before being reconsidered for proxied requests
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endpointFailureWait = 5 * time.Second
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// how often the proxy will attempt to refresh its set of endpoints
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refreshEndpoints = 30 * time.Second
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)
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func newDirector(urlsFunc GetProxyURLs) *director {
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d := &director{
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uf: urlsFunc,
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}
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d.refresh()
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go func() {
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for {
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select {
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case <-time.After(refreshEndpoints):
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d.refresh()
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}
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}
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}()
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return d
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}
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type director struct {
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sync.Mutex
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ep []*endpoint
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uf GetProxyURLs
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}
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func (d *director) refresh() {
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urls := d.uf()
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d.Lock()
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defer d.Unlock()
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var endpoints []*endpoint
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for _, u := range urls {
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uu, err := url.Parse(u)
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if err != nil {
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log.Printf("proxy: upstream URL invalid: %v", err)
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continue
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}
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endpoints = append(endpoints, newEndpoint(*uu))
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}
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d.ep = endpoints
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}
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func (d *director) endpoints() []*endpoint {
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d.Lock()
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defer d.Unlock()
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filtered := make([]*endpoint, 0)
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for _, ep := range d.ep {
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if ep.Available {
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filtered = append(filtered, ep)
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}
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}
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return filtered
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}
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func newEndpoint(u url.URL) *endpoint {
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ep := endpoint{
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URL: u,
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Available: true,
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failFunc: timedUnavailabilityFunc(endpointFailureWait),
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}
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return &ep
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}
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type endpoint struct {
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sync.Mutex
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URL url.URL
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Available bool
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failFunc func(ep *endpoint)
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}
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func (ep *endpoint) Failed() {
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ep.Lock()
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if !ep.Available {
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ep.Unlock()
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return
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}
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ep.Available = false
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ep.Unlock()
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log.Printf("proxy: marked endpoint %s unavailable", ep.URL.String())
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if ep.failFunc == nil {
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log.Printf("proxy: no failFunc defined, endpoint %s will be unavailable forever.", ep.URL.String())
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return
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}
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ep.failFunc(ep)
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}
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func timedUnavailabilityFunc(wait time.Duration) func(*endpoint) {
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return func(ep *endpoint) {
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time.AfterFunc(wait, func() {
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ep.Available = true
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log.Printf("proxy: marked endpoint %s available", ep.URL.String())
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})
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}
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}
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