Continue scrape with duplicated metrics

Problems of a single collector, like duplicated metrics read via the
textfile collector, should not fail the collection and export of other
metrics.

1 files changed, 85 insertions, 47 deletions

diff --git a/node_exporter_test.go b/node_exporter_test.go
index 4ff0caa..d1830ec 100644
--- a/node_exporter_test.go
+++ b/node_exporter_test.go
@@ -2,21 +2,23 @@ package main
 
 import (
         "fmt"
+        "io/ioutil"
         "net/http"
         "os"
         "os/exec"
+        "path/filepath"
         "testing"
         "time"
 
         "github.com/prometheus/procfs"
 )
 
-func TestFileDescriptorLeak(t *testing.T) {
-        const (
-                binary  = "./node_exporter"
-                address = "localhost:9100"
-        )
+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)
         }
@@ -24,75 +26,111 @@ func TestFileDescriptorLeak(t *testing.T) {
                 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
+        test := func(pid int) error {
+                if err := queryExporter(address); err != nil {
+                        return err
                 }
                 proc, err := procfs.NewProc(pid)
                 if err != nil {
-                        errc <- err
-                        return
+                        return err
                 }
                 fdsBefore, err := proc.FileDescriptors()
                 if err != nil {
-                        errc <- err
-                        return
+                        return err
                 }
                 for i := 0; i < 5; i++ {
-                        if err := queryExporter(url); err != nil {
-                                errc <- err
-                                return
+                        if err := queryExporter(address); err != nil {
+                                return err
                         }
                 }
                 fdsAfter, err := proc.FileDescriptors()
                 if err != nil {
-                        errc <- err
-                        return
+                        return err
                 }
                 if want, have := len(fdsBefore), len(fdsAfter); want != have {
-                        errc <- fmt.Errorf("want %d open file descriptors after metrics scrape, have %d", want, have)
+                        return 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))
+                return nil
+        }
 
-        select {
-        case err := <-errc:
-                if exporter.Process != nil {
-                        exporter.Process.Kill()
-                }
-                if err != nil {
-                        t.Fatal(err)
-                }
+        if err := runCommandAndTests(exporter, test); err != nil {
+                t.Error(err)
         }
 }
 
-func queryExporter(url string) error {
-        resp, err := http.Get(url)
+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 := resp.StatusCode, http.StatusOK; want != have {
+        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
+}