node_exporter/node_exporter_test.go

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package main
import (
"fmt"
"net/http"
"os"
"os/exec"
"testing"
"time"
"github.com/prometheus/procfs"
)
func TestFileDescriptorLeak(t *testing.T) {
const (
binary = "./node_exporter"
address = "localhost:9100"
)
if _, err := os.Stat(binary); err != nil {
t.Skipf("node_exporter binary not available, try to run `make build` first: %s", err)
}
if _, err := procfs.NewStat(); err != nil {
t.Skipf("proc filesystem is not available, but currently required to read number of open file descriptors: %s", err)
}
errc := make(chan error)
exporter := exec.Command(binary, "-web.listen-address", address)
go func() {
if err := exporter.Run(); err != nil {
errc <- fmt.Errorf("execution of node_exporter failed: %s", err)
} else {
errc <- nil
}
}()
select {
case err := <-errc:
t.Fatal(err)
case <-time.After(100 * time.Millisecond):
}
go func(pid int, url string) {
if err := queryExporter(url); err != nil {
errc <- err
return
}
proc, err := procfs.NewProc(pid)
if err != nil {
errc <- err
return
}
fdsBefore, err := proc.FileDescriptors()
if err != nil {
errc <- err
return
}
for i := 0; i < 5; i++ {
if err := queryExporter(url); err != nil {
errc <- err
return
}
}
fdsAfter, err := proc.FileDescriptors()
if err != nil {
errc <- err
return
}
if want, have := len(fdsBefore), len(fdsAfter); want != have {
errc <- fmt.Errorf("want %d open file descriptors after metrics scrape, have %d", want, have)
}
errc <- nil
}(exporter.Process.Pid, fmt.Sprintf("http://%s/metrics", address))
select {
case err := <-errc:
if exporter.Process != nil {
exporter.Process.Kill()
}
if err != nil {
t.Fatal(err)
}
}
}
func queryExporter(url string) error {
resp, err := http.Get(url)
if err != nil {
return err
}
if err := resp.Body.Close(); err != nil {
return err
}
if want, have := resp.StatusCode, http.StatusOK; want != have {
return fmt.Errorf("want /metrics status code %d, have %d", want, have)
}
return nil
}