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postgres_exporter.go
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package main
import (
"context"
stdlog "log"
"net"
"net/http"
"os"
"sync"
"time"
// _ "net/http/pprof"
kitlog "github.com/go-kit/log"
"github.com/go-kit/log/level"
pgx "github.com/jackc/pgx/v4"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/prometheus/common/version"
"github.com/rnaveiras/postgres_exporter/collector"
"github.com/rnaveiras/postgres_exporter/gokitadapter"
"gopkg.in/alecthomas/kingpin.v2"
)
const (
readHeaderTimeout = 3 * time.Second
levelError = "error" // Used for error logging
exitCodeError = 1
)
var handlerLock sync.Mutex
var (
listenAddress = kingpin.Flag("web.listen-address",
"Address on which to expose metrics and web interface.").Default("0.0.0.0:9187").String()
metricsPath = kingpin.Flag("web.telemetry-path",
"Path under which to expose metrics.").Default("/metrics").String()
dataSource = kingpin.Flag("db.data-source",
"libpq compatible data source, e.g `user=postgres host=/var/run/postgresql`. Leave blank for libpq envs").String()
logLevel = kingpin.Flag("log.level",
"Only log messages with the given severity or above. Valid levels: [debug, info, warn, error, fatal]").Default("info").String()
)
func main() {
kingpin.Version(version.Print("postgres_exporter"))
kingpin.HelpFlag.Short('h')
kingpin.Parse()
logger := kitlog.NewLogfmtLogger(kitlog.NewSyncWriter(os.Stderr))
l, err := setlogLevel(*logLevel)
if err != nil {
level.Error(logger).Log(levelError, err)
os.Exit(exitCodeError)
}
logger = level.NewFilter(logger, l)
logger = kitlog.With(logger, "ts", kitlog.DefaultTimestampUTC, "caller", kitlog.DefaultCaller)
stdlog.SetOutput(kitlog.NewStdlibAdapter(logger))
level.Info(logger).Log("msg", "Starting Postgres exporter", "version", version.Info())
level.Info(logger).Log("build_context", version.BuildContext())
connConfig, err := pgx.ParseConfig(*dataSource)
if err != nil {
level.Error(logger).Log(levelError, err)
os.Exit(exitCodeError)
}
level.Info(logger).Log("user", connConfig.User, "host", connConfig.Host, "dbname", connConfig.Database)
connConfig.RuntimeParams = map[string]string{
"client_encoding": "UTF8",
"application_name": "postgres_exporter",
}
connConfig.Logger = gokitadapter.NewLogger(logger)
connConfig.LogLevel = pgx.LogLevelNone
if *logLevel != "info" {
connConfig.LogLevel, err = pgx.LogLevelFromString(*logLevel)
if err != nil {
level.Error(logger).Log(levelError, err)
os.Exit(exitCodeError)
}
}
http.Handle(*metricsPath, metricsHandler(logger, connConfig))
http.Handle("/", catchHandler(logger, metricsPath))
level.Info(logger).Log("component", "web", "msg", "Start listening for connections", "address", *listenAddress)
server := &http.Server{
Addr: *listenAddress,
ReadHeaderTimeout: readHeaderTimeout,
BaseContext: func(_ net.Listener) context.Context { return context.Background() },
}
err = server.ListenAndServe()
if err != nil {
level.Error(logger).Log("error", err)
}
}
func catchHandler(logger kitlog.Logger, metricsPath *string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
w.Header().Set("Content-Type", "text/plain")
w.WriteHeader(http.StatusOK)
_, err := w.Write([]byte(`<html>
<head><title>postgres Exporter</title></head>
<body>
<h1>Postgres Exporter</h1>
<p><a href="` + *metricsPath + `">Metrics</a></p>
</body>
</html>`))
level.Error(logger).Log("error", err)
})
}
func metricsHandler(logger kitlog.Logger, connConfig *pgx.ConnConfig) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
handlerLock.Lock()
defer handlerLock.Unlock()
registry := prometheus.NewRegistry()
registry.MustRegister(version.NewCollector("postgres_exporter"))
registry.MustRegister(collector.NewExporter(r.Context(), logger, connConfig))
gatherers := prometheus.Gatherers{
prometheus.DefaultGatherer,
registry, // postgres_exporter metrics
}
// Delegate http serving to Prometheus client library, which will call collector.Collect.
h := promhttp.InstrumentMetricHandler(
prometheus.DefaultRegisterer,
promhttp.HandlerFor(gatherers, promhttp.HandlerOpts{
ErrorHandling: promhttp.ContinueOnError,
Registry: registry,
MaxRequestsInFlight: 15,
}))
h.ServeHTTP(w, r)
})
}
func setlogLevel(s string) (level.Option, error) {
var o level.Option
switch s {
case "debug":
o = level.AllowDebug()
case "info":
o = level.AllowInfo()
case "warn":
o = level.AllowWarn()
case "error":
o = level.AllowError()
default:
return level.AllowAll(), errors.Errorf("unrecognized log level %q", s)
}
return o, nil
}