Bring the textfile collector over from node_exporter (#174)

Bring the textfile collector over from node_exporter

This adds a slightly modified textfile collector from the official
node_exporter project.

.gitignore

@@ -1,2 +1,4 @@
 *.exe
 VERSION
+*.swp
+*.un~

README.md

@@ -22,6 +22,7 @@ process | [Win32_PerfRawData_PerfProc_Process](https://msdn.microsoft.com/en-us/
 service | [Win32_Service](https://msdn.microsoft.com/en-us/library/aa394418(v=vs.85).aspx) metrics (service states) | ✓
 system | Win32_PerfRawData_PerfOS_System metrics (system calls) | ✓
 tcp | [Win32_PerfRawData_Tcpip_TCPv4](https://msdn.microsoft.com/en-us/library/aa394341(v=vs.85).aspx) metrics (tcp connections) |
+textfile | Read prometheus metrics from a text file | ✓
 vmware | Performance counters installed by the Vmware Guest agent |
 
 The HELP texts shows the WMI data source, please see MSDN documentation for details.
@@ -39,6 +40,7 @@ Name | Description
 `LISTEN_ADDR` | The IP address to bind to. Defaults to 0.0.0.0
 `LISTEN_PORT` | The port to bind to. Defaults to 9182.
 `METRICS_PATH` | The path at which to serve metrics. Defaults to `/metrics`
+`TEXTFILE_DIR` | As the `--collector.textfile.directory` flag, provide a directory to read text files with metrics from
 
 Parameters are sent to the installer via `msiexec`. Example invocation:
 

collector/textfile.go

@@ -0,0 +1,255 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !notextfile
+
+package collector
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/common/log"
+    kingpin "gopkg.in/alecthomas/kingpin.v2"
+)
+
+var (
+    textFileDirectory = kingpin.Flag(
+        "collector.textfile.directory",
+        "Directory to read text files with metrics from.",
+    ).Default("C:\\Program Files\\wmi_exporter\\textfile_inputs").String()
+
+	mtimeDesc         = prometheus.NewDesc(
+		"wmi_textfile_mtime_seconds",
+		"Unixtime mtime of textfiles successfully read.",
+		[]string{"file"},
+		nil,
+	)
+)
+
+type textFileCollector struct {
+	path string
+	// Only set for testing to get predictable output.
+	mtime *float64
+}
+
+func init() {
+	Factories["textfile"] = NewTextFileCollector
+}
+
+// NewTextFileCollector returns a new Collector exposing metrics read from files
+// in the given textfile directory.
+func NewTextFileCollector() (Collector, error) {
+	return &textFileCollector{
+		path: *textFileDirectory,
+	}, nil
+}
+
+func convertMetricFamily(metricFamily *dto.MetricFamily, ch chan<- prometheus.Metric) {
+	var valType prometheus.ValueType
+	var val float64
+
+	allLabelNames := map[string]struct{}{}
+	for _, metric := range metricFamily.Metric {
+		labels := metric.GetLabel()
+		for _, label := range labels {
+			if _, ok := allLabelNames[label.GetName()]; !ok {
+				allLabelNames[label.GetName()] = struct{}{}
+			}
+		}
+	}
+
+	for _, metric := range metricFamily.Metric {
+		if metric.TimestampMs != nil {
+			log.Warnf("Ignoring unsupported custom timestamp on textfile collector metric %v", metric)
+		}
+
+		labels := metric.GetLabel()
+		var names []string
+		var values []string
+		for _, label := range labels {
+			names = append(names, label.GetName())
+			values = append(values, label.GetValue())
+		}
+
+		for k := range allLabelNames {
+			present := false
+			for _, name := range names {
+				if k == name {
+					present = true
+					break
+				}
+			}
+			if present == false {
+				names = append(names, k)
+				values = append(values, "")
+			}
+		}
+
+		metricType := metricFamily.GetType()
+		switch metricType {
+		case dto.MetricType_COUNTER:
+			valType = prometheus.CounterValue
+			val = metric.Counter.GetValue()
+
+		case dto.MetricType_GAUGE:
+			valType = prometheus.GaugeValue
+			val = metric.Gauge.GetValue()
+
+		case dto.MetricType_UNTYPED:
+			valType = prometheus.UntypedValue
+			val = metric.Untyped.GetValue()
+
+		case dto.MetricType_SUMMARY:
+			quantiles := map[float64]float64{}
+			for _, q := range metric.Summary.Quantile {
+				quantiles[q.GetQuantile()] = q.GetValue()
+			}
+			ch <- prometheus.MustNewConstSummary(
+				prometheus.NewDesc(
+					*metricFamily.Name,
+					metricFamily.GetHelp(),
+					names, nil,
+				),
+				metric.Summary.GetSampleCount(),
+				metric.Summary.GetSampleSum(),
+				quantiles, values...,
+			)
+		case dto.MetricType_HISTOGRAM:
+			buckets := map[float64]uint64{}
+			for _, b := range metric.Histogram.Bucket {
+				buckets[b.GetUpperBound()] = b.GetCumulativeCount()
+			}
+			ch <- prometheus.MustNewConstHistogram(
+				prometheus.NewDesc(
+					*metricFamily.Name,
+					metricFamily.GetHelp(),
+					names, nil,
+				),
+				metric.Histogram.GetSampleCount(),
+				metric.Histogram.GetSampleSum(),
+				buckets, values...,
+			)
+		default:
+            log.Errorf("unknown metric type for file")
+            continue
+		}
+		if metricType == dto.MetricType_GAUGE || metricType == dto.MetricType_COUNTER || metricType == dto.MetricType_UNTYPED {
+			ch <- prometheus.MustNewConstMetric(
+				prometheus.NewDesc(
+					*metricFamily.Name,
+					metricFamily.GetHelp(),
+					names, nil,
+				),
+				valType, val, values...,
+			)
+		}
+	}
+}
+
+func (c *textFileCollector) exportMTimes(mtimes map[string]time.Time, ch chan<- prometheus.Metric) {
+	// Export the mtimes of the successful files.
+	if len(mtimes) > 0 {
+		// Sorting is needed for predictable output comparison in tests.
+		filenames := make([]string, 0, len(mtimes))
+		for filename := range mtimes {
+			filenames = append(filenames, filename)
+		}
+		sort.Strings(filenames)
+
+		for _, filename := range filenames {
+			mtime := float64(mtimes[filename].UnixNano() / 1e9)
+			if c.mtime != nil {
+				mtime = *c.mtime
+			}
+			ch <- prometheus.MustNewConstMetric(mtimeDesc, prometheus.GaugeValue, mtime, filename)
+		}
+	}
+}
+
+// Update implements the Collector interface.
+func (c *textFileCollector) Collect(ch chan<- prometheus.Metric) error {
+	error := 0.0
+	mtimes := map[string]time.Time{}
+
+	// Iterate over files and accumulate their metrics.
+	files, err := ioutil.ReadDir(c.path)
+	if err != nil && c.path != "" {
+		log.Errorf("Error reading textfile collector directory %q: %s", c.path, err)
+		error = 1.0
+	}
+
+fileLoop:
+	for _, f := range files {
+		if !strings.HasSuffix(f.Name(), ".prom") {
+			continue
+		}
+		path := filepath.Join(c.path, f.Name())
+		file, err := os.Open(path)
+		if err != nil {
+			log.Errorf("Error opening %q: %v", path, err)
+			error = 1.0
+			continue
+		}
+		var parser expfmt.TextParser
+		parsedFamilies, err := parser.TextToMetricFamilies(file)
+		file.Close()
+		if err != nil {
+			log.Errorf("Error parsing %q: %v", path, err)
+			error = 1.0
+			continue
+		}
+		for _, mf := range parsedFamilies {
+			for _, m := range mf.Metric {
+				if m.TimestampMs != nil {
+					log.Errorf("Textfile %q contains unsupported client-side timestamps, skipping entire file", path)
+					error = 1.0
+					continue fileLoop
+				}
+			}
+			if mf.Help == nil {
+				help := fmt.Sprintf("Metric read from %s", path)
+				mf.Help = &help
+			}
+		}
+
+		// Only set this once it has been parsed and validated, so that
+		// a failure does not appear fresh.
+		mtimes[f.Name()] = f.ModTime()
+
+		for _, mf := range parsedFamilies {
+			convertMetricFamily(mf, ch)
+		}
+	}
+
+	c.exportMTimes(mtimes, ch)
+
+	// Export if there were errors.
+	ch <- prometheus.MustNewConstMetric(
+		prometheus.NewDesc(
+			"wmi_textfile_scrape_error",
+			"1 if there was an error opening or reading a file, 0 otherwise",
+			nil, nil,
+		),
+		prometheus.GaugeValue, error,
+	)
+	return nil
+}

exporter.go

@@ -26,7 +26,7 @@ type WmiCollector struct {
 }
 
 const (
-	defaultCollectors            = "cpu,cs,logical_disk,net,os,service,system"
+	defaultCollectors            = "cpu,cs,logical_disk,net,os,service,system,textfile"
 	defaultCollectorsPlaceholder = "[defaults]"
 	serviceName                  = "wmi_exporter"
 )

installer/wmi_exporter.wxs

@@ -31,12 +31,15 @@
       </Directory>
     </Directory>
 
+    <Property Id="TEXTFILE_DIR" Secure="yes"/>
+    <SetProperty Id="TextfileDirFlag" After="InstallFiles" Sequence="execute" Value="--collector.textfile.directory [TEXTFILE_DIR]">TEXTFILE_DIR</SetProperty>
+
     <ComponentGroup Id="Files" Directory="APPLICATIONROOTDIRECTORY">
       <Component>
         <File Id="wmi_exporter.exe" Name="wmi_exporter.exe" Source="Work\wmi_exporter.exe" KeyPath="yes">
           <fw:FirewallException Id="MetricsEndpoint" Name="WMI Exporter (HTTP [LISTEN_PORT])" Description="WMI Exporter HTTP endpoint" Port="[LISTEN_PORT]" Protocol="tcp" Scope="any" IgnoreFailure="yes" />
         </File>
-        <ServiceInstall Id="InstallExporterService" Name="wmi_exporter" DisplayName="WMI exporter" Description="Exports Prometheus metrics from WMI queries" ErrorControl="normal" Start="auto" Type="ownProcess" Arguments="--log.format logger:eventlog?name=wmi_exporter [CollectorsFlag] [ListenFlag] [MetricsPathFlag]" />
+        <ServiceInstall Id="InstallExporterService" Name="wmi_exporter" DisplayName="WMI exporter" Description="Exports Prometheus metrics from WMI queries" ErrorControl="normal" Start="auto" Type="ownProcess" Arguments="--log.format logger:eventlog?name=wmi_exporter [CollectorsFlag] [ListenFlag] [MetricsPathFlag] [TextfileDirFlag]" />
         <ServiceControl Id="ServiceStateControl" Name="wmi_exporter" Remove="uninstall" Start="install" Stop="both" />
       </Component>
     </ComponentGroup>