Test node_exporter for file descriptor leaks

1 files changed, 98 insertions, 0 deletions

diff --git a/node_exporter_test.go b/node_exporter_test.go
new file mode 100644
index 0000000..4ff0caa
--- /dev/null
+++ b/node_exporter_test.go
@@ -0,0 +1,98 @@
+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
+}