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// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package web
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
stdlog "log"
"math"
"net"
"net/http"
"net/http/pprof"
"net/url"
"os"
"path"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"time"
"github.com/alecthomas/units"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/grafana/regexp"
conntrack "github.com/mwitkow/go-conntrack"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
io_prometheus_client "github.com/prometheus/client_model/go"
"github.com/prometheus/common/model"
"github.com/prometheus/common/route"
"github.com/prometheus/common/server"
toolkit_web "github.com/prometheus/exporter-toolkit/web"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
"go.uber.org/atomic"
"golang.org/x/net/netutil"
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/notifier"
"github.com/prometheus/prometheus/promql"
"github.com/prometheus/prometheus/rules"
"github.com/prometheus/prometheus/scrape"
"github.com/prometheus/prometheus/storage"
"github.com/prometheus/prometheus/template"
"github.com/prometheus/prometheus/util/httputil"
api_v1 "github.com/prometheus/prometheus/web/api/v1"
"github.com/prometheus/prometheus/web/ui"
)
// Paths that are handled by the React / Reach router that should all be served the main React app's index.html.
var reactRouterPaths = []string{
"/config",
"/flags",
"/service-discovery",
"/status",
"/targets",
"/starting",
}
// Paths that are handled by the React router when the Agent mode is set.
var reactRouterAgentPaths = []string{
"/agent",
}
// Paths that are handled by the React router when the Agent mode is not set.
var reactRouterServerPaths = []string{
"/alerts",
"/graph",
"/rules",
"/tsdb-status",
}
// withStackTrace logs the stack trace in case the request panics. The function
// will re-raise the error which will then be handled by the net/http package.
// It is needed because the go-kit log package doesn't manage properly the
// panics from net/http (see https://github.com/go-kit/kit/issues/233).
func withStackTracer(h http.Handler, l log.Logger) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
defer func() {
if err := recover(); err != nil {
const size = 64 << 10
buf := make([]byte, size)
buf = buf[:runtime.Stack(buf, false)]
level.Error(l).Log("msg", "panic while serving request", "client", r.RemoteAddr, "url", r.URL, "err", err, "stack", buf)
panic(err)
}
}()
h.ServeHTTP(w, r)
})
}
type metrics struct {
requestCounter *prometheus.CounterVec
requestDuration *prometheus.HistogramVec
responseSize *prometheus.HistogramVec
readyStatus prometheus.Gauge
}
func newMetrics(r prometheus.Registerer) *metrics {
m := &metrics{
requestCounter: prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "prometheus_http_requests_total",
Help: "Counter of HTTP requests.",
},
[]string{"handler", "code"},
),
requestDuration: prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "prometheus_http_request_duration_seconds",
Help: "Histogram of latencies for HTTP requests.",
Buckets: []float64{.1, .2, .4, 1, 3, 8, 20, 60, 120},
},
[]string{"handler"},
),
responseSize: prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "prometheus_http_response_size_bytes",
Help: "Histogram of response size for HTTP requests.",
Buckets: prometheus.ExponentialBuckets(100, 10, 8),
},
[]string{"handler"},
),
readyStatus: prometheus.NewGauge(prometheus.GaugeOpts{
Name: "prometheus_ready",
Help: "Whether Prometheus startup was fully completed and the server is ready for normal operation.",
}),
}
if r != nil {
r.MustRegister(m.requestCounter, m.requestDuration, m.responseSize, m.readyStatus)
registerFederationMetrics(r)
}
return m
}
func (m *metrics) instrumentHandlerWithPrefix(prefix string) func(handlerName string, handler http.HandlerFunc) http.HandlerFunc {
return func(handlerName string, handler http.HandlerFunc) http.HandlerFunc {
return m.instrumentHandler(prefix+handlerName, handler)
}
}
func (m *metrics) instrumentHandler(handlerName string, handler http.HandlerFunc) http.HandlerFunc {
return promhttp.InstrumentHandlerCounter(
m.requestCounter.MustCurryWith(prometheus.Labels{"handler": handlerName}),
promhttp.InstrumentHandlerDuration(
m.requestDuration.MustCurryWith(prometheus.Labels{"handler": handlerName}),
promhttp.InstrumentHandlerResponseSize(
m.responseSize.MustCurryWith(prometheus.Labels{"handler": handlerName}),
handler,
),
),
)
}
// PrometheusVersion contains build information about Prometheus.
type PrometheusVersion = api_v1.PrometheusVersion
type LocalStorage interface {
storage.Storage
api_v1.TSDBAdminStats
}
// Handler serves various HTTP endpoints of the Prometheus server
type Handler struct {
logger log.Logger
gatherer prometheus.Gatherer
metrics *metrics
scrapeManager *scrape.Manager
ruleManager *rules.Manager
queryEngine *promql.Engine
lookbackDelta time.Duration
context context.Context
storage storage.Storage
localStorage LocalStorage
exemplarStorage storage.ExemplarQueryable
notifier *notifier.Manager
apiV1 *api_v1.API
router *route.Router
quitCh chan struct{}
quitOnce sync.Once
reloadCh chan chan error
options *Options
config *config.Config
versionInfo *PrometheusVersion
birth time.Time
cwd string
flagsMap map[string]string
mtx sync.RWMutex
now func() model.Time
ready atomic.Uint32 // ready is uint32 rather than boolean to be able to use atomic functions.
}
// ApplyConfig updates the config field of the Handler struct
func (h *Handler) ApplyConfig(conf *config.Config) error {
h.mtx.Lock()
defer h.mtx.Unlock()
h.config = conf
return nil
}
// Options for the web Handler.
type Options struct {
Context context.Context
TSDBRetentionDuration model.Duration
TSDBDir string
TSDBMaxBytes units.Base2Bytes
LocalStorage LocalStorage
Storage storage.Storage
ExemplarStorage storage.ExemplarQueryable
QueryEngine *promql.Engine
LookbackDelta time.Duration
ScrapeManager *scrape.Manager
RuleManager *rules.Manager
Notifier *notifier.Manager
Version *PrometheusVersion
Flags map[string]string
ListenAddress string
CORSOrigin *regexp.Regexp
ReadTimeout time.Duration
MaxConnections int
ExternalURL *url.URL
RoutePrefix string
UseLocalAssets bool
UserAssetsPath string
ConsoleTemplatesPath string
ConsoleLibrariesPath string
EnableLifecycle bool
EnableAdminAPI bool
PageTitle string
RemoteReadSampleLimit int
RemoteReadConcurrencyLimit int
RemoteReadBytesInFrame int
EnableRemoteWriteReceiver bool
IsAgent bool
AppName string
Gatherer prometheus.Gatherer
Registerer prometheus.Registerer
}
// New initializes a new web Handler.
func New(logger log.Logger, o *Options) *Handler {
if logger == nil {
logger = log.NewNopLogger()
}
m := newMetrics(o.Registerer)
router := route.New().
WithInstrumentation(m.instrumentHandler).
WithInstrumentation(setPathWithPrefix(""))
cwd, err := os.Getwd()
if err != nil {
cwd = "<error retrieving current working directory>"
}
h := &Handler{
logger: logger,
gatherer: o.Gatherer,
metrics: m,
router: router,
quitCh: make(chan struct{}),
reloadCh: make(chan chan error),
options: o,
versionInfo: o.Version,
birth: time.Now().UTC(),
cwd: cwd,
flagsMap: o.Flags,
context: o.Context,
scrapeManager: o.ScrapeManager,
ruleManager: o.RuleManager,
queryEngine: o.QueryEngine,
lookbackDelta: o.LookbackDelta,
storage: o.Storage,
localStorage: o.LocalStorage,
exemplarStorage: o.ExemplarStorage,
notifier: o.Notifier,
now: model.Now,
}
h.SetReady(false)
factoryTr := func(_ context.Context) api_v1.TargetRetriever { return h.scrapeManager }
factoryAr := func(_ context.Context) api_v1.AlertmanagerRetriever { return h.notifier }
FactoryRr := func(_ context.Context) api_v1.RulesRetriever { return h.ruleManager }
var app storage.Appendable
if o.EnableRemoteWriteReceiver {
app = h.storage
}
h.apiV1 = api_v1.NewAPI(h.queryEngine, h.storage, app, h.exemplarStorage, factoryTr, factoryAr,
func() config.Config {
h.mtx.RLock()
defer h.mtx.RUnlock()
return *h.config
},
o.Flags,
api_v1.GlobalURLOptions{
ListenAddress: o.ListenAddress,
Host: o.ExternalURL.Host,
Scheme: o.ExternalURL.Scheme,
},
h.testReady,
h.options.LocalStorage,
h.options.TSDBDir,
h.options.EnableAdminAPI,
logger,
FactoryRr,
h.options.RemoteReadSampleLimit,
h.options.RemoteReadConcurrencyLimit,
h.options.RemoteReadBytesInFrame,
h.options.IsAgent,
h.options.CORSOrigin,
h.runtimeInfo,
h.versionInfo,
o.Gatherer,
o.Registerer,
nil,
)
if o.RoutePrefix != "/" {
// If the prefix is missing for the root path, prepend it.
router.Get("/", func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, o.RoutePrefix, http.StatusFound)
})
router = router.WithPrefix(o.RoutePrefix)
}
homePage := "/graph"
if o.IsAgent {
homePage = "/agent"
}
readyf := h.testReady
router.Get("/", func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, path.Join(o.ExternalURL.Path, homePage), http.StatusFound)
})
// The console library examples at 'console_libraries/prom.lib' still depend on old asset files being served under `classic`.
router.Get("/classic/static/*filepath", func(w http.ResponseWriter, r *http.Request) {
r.URL.Path = path.Join("/static", route.Param(r.Context(), "filepath"))
fs := server.StaticFileServer(ui.Assets)
fs.ServeHTTP(w, r)
})
router.Get("/version", h.version)
router.Get("/metrics", promhttp.Handler().ServeHTTP)
router.Get("/federate", readyf(httputil.CompressionHandler{
Handler: http.HandlerFunc(h.federation),
}.ServeHTTP))
router.Get("/consoles/*filepath", readyf(h.consoles))
serveReactApp := func(w http.ResponseWriter, r *http.Request) {
f, err := ui.Assets.Open("/static/react/index.html")
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
fmt.Fprintf(w, "Error opening React index.html: %v", err)
return
}
defer func() { _ = f.Close() }()
idx, err := io.ReadAll(f)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
fmt.Fprintf(w, "Error reading React index.html: %v", err)
return
}
replacedIdx := bytes.ReplaceAll(idx, []byte("CONSOLES_LINK_PLACEHOLDER"), []byte(h.consolesPath()))
replacedIdx = bytes.ReplaceAll(replacedIdx, []byte("TITLE_PLACEHOLDER"), []byte(h.options.PageTitle))
replacedIdx = bytes.ReplaceAll(replacedIdx, []byte("AGENT_MODE_PLACEHOLDER"), []byte(strconv.FormatBool(h.options.IsAgent)))
w.Write(replacedIdx)
}
// Serve the React app.
for _, p := range reactRouterPaths {
router.Get(p, serveReactApp)
}
if h.options.IsAgent {
for _, p := range reactRouterAgentPaths {
router.Get(p, serveReactApp)
}
} else {
for _, p := range reactRouterServerPaths {
router.Get(p, serveReactApp)
}
}
// The favicon and manifest are bundled as part of the React app, but we want to serve
// them on the root.
for _, p := range []string{"/favicon.ico", "/manifest.json"} {
assetPath := "/static/react" + p
router.Get(p, func(w http.ResponseWriter, r *http.Request) {
r.URL.Path = assetPath
fs := server.StaticFileServer(ui.Assets)
fs.ServeHTTP(w, r)
})
}
// Static files required by the React app.
router.Get("/static/*filepath", func(w http.ResponseWriter, r *http.Request) {
r.URL.Path = path.Join("/static/react/static", route.Param(r.Context(), "filepath"))
fs := server.StaticFileServer(ui.Assets)
fs.ServeHTTP(w, r)
})
if o.UserAssetsPath != "" {
router.Get("/user/*filepath", route.FileServe(o.UserAssetsPath))
}
if o.EnableLifecycle {
router.Post("/-/quit", h.quit)
router.Put("/-/quit", h.quit)
router.Post("/-/reload", h.reload)
router.Put("/-/reload", h.reload)
} else {
forbiddenAPINotEnabled := func(w http.ResponseWriter, _ *http.Request) {
w.WriteHeader(http.StatusForbidden)
w.Write([]byte("Lifecycle API is not enabled."))
}
router.Post("/-/quit", forbiddenAPINotEnabled)
router.Put("/-/quit", forbiddenAPINotEnabled)
router.Post("/-/reload", forbiddenAPINotEnabled)
router.Put("/-/reload", forbiddenAPINotEnabled)
}
router.Get("/-/quit", func(w http.ResponseWriter, _ *http.Request) {
w.WriteHeader(http.StatusMethodNotAllowed)
w.Write([]byte("Only POST or PUT requests allowed"))
})
router.Get("/-/reload", func(w http.ResponseWriter, _ *http.Request) {
w.WriteHeader(http.StatusMethodNotAllowed)
w.Write([]byte("Only POST or PUT requests allowed"))
})
router.Get("/debug/*subpath", serveDebug)
router.Post("/debug/*subpath", serveDebug)
router.Get("/-/healthy", func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
fmt.Fprintf(w, o.AppName+" is Healthy.\n")
})
router.Get("/-/ready", readyf(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
fmt.Fprintf(w, o.AppName+" is Ready.\n")
}))
return h
}
func serveDebug(w http.ResponseWriter, req *http.Request) {
ctx := req.Context()
subpath := route.Param(ctx, "subpath")
if subpath == "/pprof" {
http.Redirect(w, req, req.URL.Path+"/", http.StatusMovedPermanently)
return
}
if !strings.HasPrefix(subpath, "/pprof/") {
http.NotFound(w, req)
return
}
subpath = strings.TrimPrefix(subpath, "/pprof/")
switch subpath {
case "cmdline":
pprof.Cmdline(w, req)
case "profile":
pprof.Profile(w, req)
case "symbol":
pprof.Symbol(w, req)
case "trace":
pprof.Trace(w, req)
default:
req.URL.Path = "/debug/pprof/" + subpath
pprof.Index(w, req)
}
}
// SetReady sets the ready status of our web Handler
func (h *Handler) SetReady(v bool) {
if v {
h.ready.Store(1)
h.metrics.readyStatus.Set(1)
return
}
h.ready.Store(0)
h.metrics.readyStatus.Set(0)
}
// Verifies whether the server is ready or not.
func (h *Handler) isReady() bool {
return h.ready.Load() > 0
}
// Checks if server is ready, calls f if it is, returns 503 if it is not.
func (h *Handler) testReady(f http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
if h.isReady() {
f(w, r)
} else {
w.WriteHeader(http.StatusServiceUnavailable)
fmt.Fprintf(w, "Service Unavailable")
}
}
}
// Quit returns the receive-only quit channel.
func (h *Handler) Quit() <-chan struct{} {
return h.quitCh
}
// Reload returns the receive-only channel that signals configuration reload requests.
func (h *Handler) Reload() <-chan chan error {
return h.reloadCh
}
// Listener creates the TCP listener for web requests.
func (h *Handler) Listener() (net.Listener, error) {
level.Info(h.logger).Log("msg", "Start listening for connections", "address", h.options.ListenAddress)
listener, err := net.Listen("tcp", h.options.ListenAddress)
if err != nil {
return listener, err
}
listener = netutil.LimitListener(listener, h.options.MaxConnections)
// Monitor incoming connections with conntrack.
listener = conntrack.NewListener(listener,
conntrack.TrackWithName("http"),
conntrack.TrackWithTracing())
return listener, nil
}
// Run serves the HTTP endpoints.
func (h *Handler) Run(ctx context.Context, listener net.Listener, webConfig string) error {
if listener == nil {
var err error
listener, err = h.Listener()
if err != nil {
return err
}
}
mux := http.NewServeMux()
mux.Handle("/", h.router)
apiPath := "/api"
if h.options.RoutePrefix != "/" {
apiPath = h.options.RoutePrefix + apiPath
level.Info(h.logger).Log("msg", "Router prefix", "prefix", h.options.RoutePrefix)
}
av1 := route.New().
WithInstrumentation(h.metrics.instrumentHandlerWithPrefix("/api/v1")).
WithInstrumentation(setPathWithPrefix(apiPath + "/v1"))
h.apiV1.Register(av1)
mux.Handle(apiPath+"/v1/", http.StripPrefix(apiPath+"/v1", av1))
errlog := stdlog.New(log.NewStdlibAdapter(level.Error(h.logger)), "", 0)
spanNameFormatter := otelhttp.WithSpanNameFormatter(func(_ string, r *http.Request) string {
return fmt.Sprintf("%s %s", r.Method, r.URL.Path)
})
httpSrv := &http.Server{
Handler: withStackTracer(otelhttp.NewHandler(mux, "", spanNameFormatter), h.logger),
ErrorLog: errlog,
ReadTimeout: h.options.ReadTimeout,
}
errCh := make(chan error, 1)
go func() {
errCh <- toolkit_web.Serve(listener, httpSrv, webConfig, h.logger)
}()
select {
case e := <-errCh:
return e
case <-ctx.Done():
httpSrv.Shutdown(ctx)
return nil
}
}
func (h *Handler) consoles(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
name := route.Param(ctx, "filepath")
file, err := http.Dir(h.options.ConsoleTemplatesPath).Open(name)
if err != nil {
http.Error(w, err.Error(), http.StatusNotFound)
return
}
defer file.Close()
text, err := io.ReadAll(file)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
ctx = httputil.ContextFromRequest(ctx, r)
// Provide URL parameters as a map for easy use. Advanced users may have need for
// parameters beyond the first, so provide RawParams.
rawParams, err := url.ParseQuery(r.URL.RawQuery)
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
params := map[string]string{}
for k, v := range rawParams {
params[k] = v[0]
}
externalLabels := map[string]string{}
h.mtx.RLock()
els := h.config.GlobalConfig.ExternalLabels
h.mtx.RUnlock()
for _, el := range els {
externalLabels[el.Name] = el.Value
}
// Inject some convenience variables that are easier to remember for users
// who are not used to Go's templating system.
defs := []string{
"{{$rawParams := .RawParams }}",
"{{$params := .Params}}",
"{{$path := .Path}}",
"{{$externalLabels := .ExternalLabels}}",
}
data := struct {
RawParams url.Values
Params map[string]string
Path string
ExternalLabels map[string]string
}{
RawParams: rawParams,
Params: params,
Path: strings.TrimLeft(name, "/"),
ExternalLabels: externalLabels,
}
tmpl := template.NewTemplateExpander(
ctx,
strings.Join(append(defs, string(text)), ""),
"__console_"+name,
data,
h.now(),
template.QueryFunc(rules.EngineQueryFunc(h.queryEngine, h.storage)),
h.options.ExternalURL,
nil,
)
filenames, err := filepath.Glob(h.options.ConsoleLibrariesPath + "/*.lib")
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
result, err := tmpl.ExpandHTML(filenames)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
io.WriteString(w, result)
}
func (h *Handler) runtimeInfo() (api_v1.RuntimeInfo, error) {
status := api_v1.RuntimeInfo{
StartTime: h.birth,
CWD: h.cwd,
GoroutineCount: runtime.NumGoroutine(),
GOMAXPROCS: runtime.GOMAXPROCS(0),
GOGC: os.Getenv("GOGC"),
GODEBUG: os.Getenv("GODEBUG"),
}
if h.options.TSDBRetentionDuration != 0 {
status.StorageRetention = h.options.TSDBRetentionDuration.String()
}
if h.options.TSDBMaxBytes != 0 {
if status.StorageRetention != "" {
status.StorageRetention = status.StorageRetention + " or "
}
status.StorageRetention = status.StorageRetention + h.options.TSDBMaxBytes.String()
}
metrics, err := h.gatherer.Gather()
if err != nil {
return status, errors.Errorf("error gathering runtime status: %s", err)
}
for _, mF := range metrics {
switch *mF.Name {
case "prometheus_tsdb_wal_corruptions_total":
status.CorruptionCount = int64(toFloat64(mF))
case "prometheus_config_last_reload_successful":
status.ReloadConfigSuccess = toFloat64(mF) != 0
case "prometheus_config_last_reload_success_timestamp_seconds":
status.LastConfigTime = time.Unix(int64(toFloat64(mF)), 0).UTC()
}
}
return status, nil
}
func toFloat64(f *io_prometheus_client.MetricFamily) float64 {
m := *f.Metric[0]
if m.Gauge != nil {
return m.Gauge.GetValue()
}
if m.Counter != nil {
return m.Counter.GetValue()
}
if m.Untyped != nil {
return m.Untyped.GetValue()
}
return math.NaN()
}
func (h *Handler) version(w http.ResponseWriter, r *http.Request) {
dec := json.NewEncoder(w)
if err := dec.Encode(h.versionInfo); err != nil {
http.Error(w, fmt.Sprintf("error encoding JSON: %s", err), http.StatusInternalServerError)
}
}
func (h *Handler) quit(w http.ResponseWriter, r *http.Request) {
var closed bool
h.quitOnce.Do(func() {
closed = true
close(h.quitCh)
fmt.Fprintf(w, "Requesting termination... Goodbye!")
})
if !closed {
fmt.Fprintf(w, "Termination already in progress.")
}
}
func (h *Handler) reload(w http.ResponseWriter, r *http.Request) {
rc := make(chan error)
h.reloadCh <- rc
if err := <-rc; err != nil {
http.Error(w, fmt.Sprintf("failed to reload config: %s", err), http.StatusInternalServerError)
}
}
func (h *Handler) consolesPath() string {
if _, err := os.Stat(h.options.ConsoleTemplatesPath + "/index.html"); !os.IsNotExist(err) {
return h.options.ExternalURL.Path + "/consoles/index.html"
}
if h.options.UserAssetsPath != "" {
if _, err := os.Stat(h.options.UserAssetsPath + "/index.html"); !os.IsNotExist(err) {
return h.options.ExternalURL.Path + "/user/index.html"
}
}
return ""
}
func setPathWithPrefix(prefix string) func(handlerName string, handler http.HandlerFunc) http.HandlerFunc {
return func(handlerName string, handler http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
handler(w, r.WithContext(httputil.ContextWithPath(r.Context(), prefix+r.URL.Path)))
}
}
}