/
main.go
201 lines (176 loc) · 6.46 KB
/
main.go
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package main
import (
"bufio"
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"os"
"strings"
kingpin "gopkg.in/alecthomas/kingpin.v2"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/prometheus/common/promlog"
"github.com/prometheus/common/promlog/flag"
"github.com/robustperception/pushprox/util"
)
const (
namespace = "pushprox_proxy" // For Prometheus metrics.
)
var (
listenAddress = kingpin.Flag("web.listen-address", "Address to listen on for proxy and client requests.").Default(":8080").String()
maxScrapeTimeout = kingpin.Flag("scrape.max-timeout", "Any scrape with a timeout higher than this will have to be clamped to this.").Default("5m").Duration()
defaultScrapeTimeout = kingpin.Flag("scrape.default-timeout", "If a scrape lacks a timeout, use this value.").Default("15s").Duration()
)
var (
httpAPICounter = prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "pushprox_http_requests_total",
Help: "Number of http api requests.",
}, []string{"code", "path"},
)
httpProxyCounter = prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "pushproxy_proxied_requests_total",
Help: "Number of http proxy requests.",
}, []string{"code"},
)
httpPathHistogram = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "pushprox_http_duration_seconds",
Help: "Time taken by path",
}, []string{"path"})
)
func init() {
prometheus.MustRegister(httpAPICounter, httpProxyCounter, httpPathHistogram)
}
func copyHTTPResponse(resp *http.Response, w http.ResponseWriter) {
for k, v := range resp.Header {
w.Header()[k] = v
}
w.WriteHeader(resp.StatusCode)
io.Copy(w, resp.Body)
}
type targetGroup struct {
Targets []string `json:"targets"`
Labels map[string]string `json:"labels"`
}
type httpHandler struct {
logger log.Logger
coordinator *Coordinator
mux http.Handler
proxy http.Handler
}
func newHTTPHandler(logger log.Logger, coordinator *Coordinator, mux *http.ServeMux) *httpHandler {
h := &httpHandler{logger: logger, coordinator: coordinator, mux: mux}
// api handlers
handlers := map[string]http.HandlerFunc{
"/push": h.handlePush,
"/poll": h.handlePoll,
"/clients": h.handleListClients,
"/metrics": promhttp.Handler().ServeHTTP,
}
for path, handlerFunc := range handlers {
counter := httpAPICounter.MustCurryWith(prometheus.Labels{"path": path})
handler := promhttp.InstrumentHandlerCounter(counter, http.HandlerFunc(handlerFunc))
histogram := httpPathHistogram.MustCurryWith(prometheus.Labels{"path": path})
handler = promhttp.InstrumentHandlerDuration(histogram, handler)
mux.Handle(path, handler)
counter.WithLabelValues("200")
if path == "/push" {
counter.WithLabelValues("500")
}
if path == "/poll" {
counter.WithLabelValues("408")
}
}
// proxy handler
h.proxy = promhttp.InstrumentHandlerCounter(httpProxyCounter, http.HandlerFunc(h.handleProxy))
return h
}
// handlePush handles scrape responses from client.
func (h *httpHandler) handlePush(w http.ResponseWriter, r *http.Request) {
buf := &bytes.Buffer{}
io.Copy(buf, r.Body)
scrapeResult, err := http.ReadResponse(bufio.NewReader(buf), nil)
if err != nil {
level.Error(h.logger).Log("msg", "Error reading pushed response:", "err", err)
http.Error(w, fmt.Sprintf("Error pushing: %s", err.Error()), 500)
return
}
level.Info(h.logger).Log("msg", "Got /push", "scrape_id", scrapeResult.Header.Get("Id"))
err = h.coordinator.ScrapeResult(scrapeResult)
if err != nil {
level.Error(h.logger).Log("msg", "Error pushing:", "err", err, "scrape_id", scrapeResult.Header.Get("Id"))
http.Error(w, fmt.Sprintf("Error pushing: %s", err.Error()), 500)
}
}
// handlePoll handles clients registering and asking for scrapes.
func (h *httpHandler) handlePoll(w http.ResponseWriter, r *http.Request) {
fqdn, _ := ioutil.ReadAll(r.Body)
request, err := h.coordinator.WaitForScrapeInstruction(strings.TrimSpace(string(fqdn)))
if err != nil {
level.Info(h.logger).Log("msg", "Error WaitForScrapeInstruction:", "err", err)
http.Error(w, fmt.Sprintf("Error WaitForScrapeInstruction: %s", err.Error()), 408)
return
}
request.WriteProxy(w) // Send full request as the body of the response.
level.Info(h.logger).Log("msg", "Responded to /poll", "url", request.URL.String(), "scrape_id", request.Header.Get("Id"))
}
// handleListClients handles requests to list available clients as a JSON array.
func (h *httpHandler) handleListClients(w http.ResponseWriter, r *http.Request) {
known := h.coordinator.KnownClients()
targets := make([]*targetGroup, 0, len(known))
for _, k := range known {
targets = append(targets, &targetGroup{Targets: []string{k}})
}
json.NewEncoder(w).Encode(targets)
level.Info(h.logger).Log("msg", "Responded to /clients", "client_count", len(known))
}
// handleProxy handles proxied scrapes from Prometheus.
func (h *httpHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
ctx, cancel := context.WithTimeout(r.Context(), util.GetScrapeTimeout(maxScrapeTimeout, defaultScrapeTimeout, r.Header))
defer cancel()
request := r.WithContext(ctx)
request.RequestURI = ""
resp, err := h.coordinator.DoScrape(ctx, request)
if err != nil {
level.Error(h.logger).Log("msg", "Error scraping:", "err", err, "url", request.URL.String())
http.Error(w, fmt.Sprintf("Error scraping %q: %s", request.URL.String(), err.Error()), 500)
return
}
defer resp.Body.Close()
copyHTTPResponse(resp, w)
}
// ServeHTTP discriminates between proxy requests (e.g. from Prometheus) and other requests (e.g. from the Client).
func (h *httpHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.URL.Host != "" { // Proxy request
h.proxy.ServeHTTP(w, r)
} else { // Non-proxy requests
h.mux.ServeHTTP(w, r)
}
}
func main() {
promlogConfig := promlog.Config{}
flag.AddFlags(kingpin.CommandLine, &promlogConfig)
kingpin.HelpFlag.Short('h')
kingpin.Parse()
logger := promlog.New(&promlogConfig)
coordinator, err := NewCoordinator(logger)
if err != nil {
level.Error(logger).Log("msg", "Coordinator initialization failed", "err", err)
os.Exit(1)
}
mux := http.NewServeMux()
handler := newHTTPHandler(logger, coordinator, mux)
level.Info(logger).Log("msg", "Listening", "address", *listenAddress)
if err := http.ListenAndServe(*listenAddress, handler); err != nil {
level.Error(logger).Log("msg", "Listening failed", "err", err)
os.Exit(1)
}
}