node_exporter/node_exporter_test.go

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package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
"os/exec"
"path/filepath"
"testing"
"time"
"github.com/prometheus/procfs"
)
const (
binary = "./node_exporter"
address = "localhost:19100"
)
func TestFileDescriptorLeak(t *testing.T) {
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)
}
exporter := exec.Command(binary, "-web.listen-address", address)
test := func(pid int) error {
if err := queryExporter(address); err != nil {
return err
}
proc, err := procfs.NewProc(pid)
if err != nil {
return err
}
fdsBefore, err := proc.FileDescriptors()
if err != nil {
return err
}
for i := 0; i < 5; i++ {
if err := queryExporter(address); err != nil {
return err
}
}
fdsAfter, err := proc.FileDescriptors()
if err != nil {
return err
}
if want, have := len(fdsBefore), len(fdsAfter); want != have {
return fmt.Errorf("want %d open file descriptors after metrics scrape, have %d", want, have)
}
return nil
}
if err := runCommandAndTests(exporter, test); err != nil {
t.Error(err)
}
}
func TestHandlingOfDuplicatedMetrics(t *testing.T) {
if _, err := os.Stat(binary); err != nil {
t.Skipf("node_exporter binary not available, try to run `make build` first: %s", err)
}
dir, err := ioutil.TempDir("", "node-exporter")
if err != nil {
t.Fatal(err)
}
defer os.RemoveAll(dir)
content := []byte("dummy_metric 1\n")
if err := ioutil.WriteFile(filepath.Join(dir, "a.prom"), content, 0600); err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(dir, "b.prom"), content, 0600); err != nil {
t.Fatal(err)
}
exporter := exec.Command(binary, "-web.listen-address", address, "-collector.textfile.directory", dir)
test := func(_ int) error {
return queryExporter(address)
}
if err := runCommandAndTests(exporter, test); err != nil {
t.Error(err)
}
}
func queryExporter(address string) error {
resp, err := http.Get(fmt.Sprintf("http://%s/metrics", address))
if err != nil {
return err
}
if err := resp.Body.Close(); err != nil {
return err
}
if want, have := http.StatusOK, resp.StatusCode; want != have {
return fmt.Errorf("want /metrics status code %d, have %d", want, have)
}
return nil
}
func runCommandAndTests(cmd *exec.Cmd, fn func(pid int) error) error {
errc := make(chan error)
go func() {
if err := cmd.Run(); err != nil {
errc <- fmt.Errorf("execution of command failed: %s", err)
} else {
errc <- nil
}
}()
// Allow the process to start before running any tests.
select {
case err := <-errc:
return err
case <-time.After(100 * time.Millisecond):
}
go func(pid int) {
errc <- fn(pid)
}(cmd.Process.Pid)
select {
case err := <-errc:
if cmd.Process != nil {
cmd.Process.Kill()
}
if err != nil {
return err
}
}
return nil
}