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package main
import (
"bytes"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"net/url"
"os"
"os/signal"
"strconv"
"strings"
"sync"
"syscall"
"time"
"github.com/gorilla/handlers"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
log15 "gopkg.in/inconshreveable/log15.v2"
"github.com/sourcegraph/sourcegraph/internal/conf"
"github.com/sourcegraph/sourcegraph/internal/debugserver"
"github.com/sourcegraph/sourcegraph/internal/env"
"github.com/sourcegraph/sourcegraph/internal/tracer"
)
var logRequests, _ = strconv.ParseBool(env.Get("LOG_REQUESTS", "", "log HTTP requests"))
const port = "3180"
// requestMu ensures we only do one request at a time to prevent tripping abuse detection.
var requestMu sync.Mutex
var rateLimitRemainingGauge = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Namespace: "src",
Subsystem: "github",
Name: "rate_limit_remaining",
Help: "Number of calls to GitHub's API remaining before hitting the rate limit.",
}, []string{"resource"})
func init() {
rateLimitRemainingGauge.WithLabelValues("core").Set(5000)
rateLimitRemainingGauge.WithLabelValues("search").Set(30)
prometheus.MustRegister(rateLimitRemainingGauge)
}
// list obtained from httputil of headers not to forward.
var hopHeaders = map[string]struct{}{
"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; http://www.rfc-editor.org/errata_search.php?eid=4522
"Transfer-Encoding": {},
"Upgrade": {},
}
func main() {
env.Lock()
env.HandleHelpFlag()
tracer.Init()
go func() {
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGINT, syscall.SIGHUP)
<-c
os.Exit(0)
}()
go debugserver.Start()
var (
authenticateRequestMu sync.RWMutex
authenticateRequest func(query url.Values, header http.Header)
)
conf.Watch(func() {
cfg := conf.Get()
if clientID, clientSecret := cfg.GithubClientID, cfg.GithubClientSecret; clientID != "" && clientSecret != "" {
authenticateRequestMu.Lock()
authenticateRequest = func(query url.Values, header http.Header) {
query.Set("client_id", clientID)
query.Set("client_secret", clientSecret)
}
authenticateRequestMu.Unlock()
}
})
// Use a custom client/transport because GitHub closes keep-alive
// connections after 60s. In order to avoid running into EOF errors, we use
// a IdleConnTimeout of 30s, so connections are only kept around for <30s
client := &http.Client{Transport: &http.Transport{
IdleConnTimeout: 30 * time.Second,
}}
var h http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
q2 := r.URL.Query()
h2 := make(http.Header)
for k, v := range r.Header {
if _, found := hopHeaders[k]; !found {
h2[k] = v
}
}
// Authenticate for higher rate limits.
authenticateRequestMu.RLock()
authRequest := authenticateRequest
authenticateRequestMu.RUnlock()
if authRequest != nil {
authRequest(q2, h2)
}
req2 := &http.Request{
Method: r.Method,
Body: r.Body,
URL: &url.URL{
Scheme: "https",
Host: "api.github.com",
Path: r.URL.Path,
RawQuery: q2.Encode(),
},
Header: h2,
}
requestMu.Lock()
resp, err := client.Do(req2)
requestMu.Unlock()
if err != nil {
log15.Warn("proxy error", "err", err)
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
defer resp.Body.Close()
if limit := resp.Header.Get("X-Ratelimit-Remaining"); limit != "" {
limit, _ := strconv.Atoi(limit)
resource := "core"
if strings.HasPrefix(r.URL.Path, "/search/") {
resource = "search"
} else if r.URL.Path == "/graphql" {
resource = "graphql"
}
rateLimitRemainingGauge.WithLabelValues(resource).Set(float64(limit))
}
for k, v := range resp.Header {
w.Header()[k] = v
}
w.WriteHeader(resp.StatusCode)
if resp.StatusCode < 400 || !logRequests {
io.Copy(w, resp.Body)
return
}
b, err := ioutil.ReadAll(resp.Body)
log15.Warn("proxy error", "status", resp.StatusCode, "body", string(b), "bodyErr", err)
io.Copy(w, bytes.NewReader(b))
})
if logRequests {
h = handlers.LoggingHandler(os.Stdout, h)
}
h = instrumentHandler(prometheus.DefaultRegisterer, h)
http.Handle("/", h)
host := ""
if env.InsecureDev {
host = "127.0.0.1"
}
addr := net.JoinHostPort(host, port)
log15.Info("github-proxy: listening", "addr", addr)
log.Fatal(http.ListenAndServe(addr, nil))
}
func instrumentHandler(r prometheus.Registerer, h http.Handler) http.Handler {
var (
inFlightGauge = prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: "src",
Subsystem: "githubproxy",
Name: "in_flight_requests",
Help: "A gauge of requests currently being served by github-proxy.",
})
counter = prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: "src",
Subsystem: "githubproxy",
Name: "requests_total",
Help: "A counter for requests to github-proxy.",
},
[]string{"code", "method"},
)
duration = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: "src",
Subsystem: "githubproxy",
Name: "request_duration_seconds",
Help: "A histogram of latencies for requests.",
Buckets: []float64{.25, .5, 1, 2.5, 5, 10},
},
[]string{"method"},
)
responseSize = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: "src",
Subsystem: "githubproxy",
Name: "response_size_bytes",
Help: "A histogram of response sizes for requests.",
Buckets: []float64{200, 500, 900, 1500},
},
[]string{},
)
)
r.MustRegister(inFlightGauge, counter, duration, responseSize)
return promhttp.InstrumentHandlerInFlight(inFlightGauge,
promhttp.InstrumentHandlerDuration(duration,
promhttp.InstrumentHandlerCounter(counter,
promhttp.InstrumentHandlerResponseSize(responseSize, h),
),
),
)
}