Add fluentd input plugin (#2661)

plugins/inputs/fluentd/fluentd.go

@@ -0,0 +1,173 @@
+package fluentd
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+const (
+	measurement  = "fluentd"
+	description  = "Read metrics exposed by fluentd in_monitor plugin"
+	sampleConfig = `
+  ## This plugin reads information exposed by fluentd (using /api/plugins.json endpoint).
+  ##
+  ## Endpoint: 
+  ## - only one URI is allowed
+  ## - https is not supported
+  endpoint = "http://localhost:24220/api/plugins.json"
+  	
+  ## Define which plugins have to be excluded (based on "type" field - e.g. monitor_agent)
+  exclude = [
+	  "monitor_agent",
+	  "dummy",
+  ]
+`
+)
+
+// Fluentd - plugin main structure
+type Fluentd struct {
+	Endpoint string
+	Exclude  []string
+	client   *http.Client
+}
+
+type endpointInfo struct {
+	Payload []pluginData `json:"plugins"`
+}
+
+type pluginData struct {
+	PluginID              string   `json:"plugin_id"`
+	PluginType            string   `json:"type"`
+	PluginCategory        string   `json:"plugin_category"`
+	RetryCount            *float64 `json:"retry_count"`
+	BufferQueueLength     *float64 `json:"buffer_queue_length"`
+	BufferTotalQueuedSize *float64 `json:"buffer_total_queued_size"`
+}
+
+// parse JSON from fluentd Endpoint
+// Parameters:
+// 		data: unprocessed json recivied from endpoint
+//
+// Returns:
+//		pluginData:		slice that contains parsed plugins
+//		error:			error that may have occurred
+func parse(data []byte) (datapointArray []pluginData, err error) {
+	var endpointData endpointInfo
+
+	if err = json.Unmarshal(data, &endpointData); err != nil {
+		err = fmt.Errorf("Processing JSON structure")
+		return
+	}
+
+	for _, point := range endpointData.Payload {
+		datapointArray = append(datapointArray, point)
+	}
+
+	return
+}
+
+// Description - display description
+func (h *Fluentd) Description() string { return description }
+
+// SampleConfig - generate configuretion
+func (h *Fluentd) SampleConfig() string { return sampleConfig }
+
+// Gather - Main code responsible for gathering, processing and creating metrics
+func (h *Fluentd) Gather(acc telegraf.Accumulator) error {
+
+	_, err := url.Parse(h.Endpoint)
+	if err != nil {
+		return fmt.Errorf("Invalid URL \"%s\"", h.Endpoint)
+	}
+
+	if h.client == nil {
+
+		tr := &http.Transport{
+			ResponseHeaderTimeout: time.Duration(3 * time.Second),
+		}
+
+		client := &http.Client{
+			Transport: tr,
+			Timeout:   time.Duration(4 * time.Second),
+		}
+
+		h.client = client
+	}
+
+	resp, err := h.client.Get(h.Endpoint)
+
+	if err != nil {
+		return fmt.Errorf("Unable to perform HTTP client GET on \"%s\": %s", h.Endpoint, err)
+	}
+
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+
+	if err != nil {
+		return fmt.Errorf("Unable to read the HTTP body \"%s\": %s", string(body), err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("http status ok not met")
+	}
+
+	dataPoints, err := parse(body)
+
+	if err != nil {
+		return fmt.Errorf("Problem with parsing")
+	}
+
+	// Go through all plugins one by one
+	for _, p := range dataPoints {
+
+		skip := false
+
+		// Check if this specific type was excluded in configuration
+		for _, exclude := range h.Exclude {
+			if exclude == p.PluginType {
+				skip = true
+			}
+		}
+
+		// If not, create new metric and add it to Accumulator
+		if !skip {
+			tmpFields := make(map[string]interface{})
+
+			tmpTags := map[string]string{
+				"plugin_id":       p.PluginID,
+				"plugin_category": p.PluginCategory,
+				"plugin_type":     p.PluginType,
+			}
+
+			if p.BufferQueueLength != nil {
+				tmpFields["buffer_queue_length"] = p.BufferQueueLength
+
+			}
+			if p.RetryCount != nil {
+				tmpFields["retry_count"] = p.RetryCount
+			}
+
+			if p.BufferTotalQueuedSize != nil {
+				tmpFields["buffer_total_queued_size"] = p.BufferTotalQueuedSize
+			}
+
+			if !((p.BufferQueueLength == nil) && (p.RetryCount == nil) && (p.BufferTotalQueuedSize == nil)) {
+				acc.AddFields(measurement, tmpFields, tmpTags)
+			}
+		}
+	}
+
+	return nil
+}
+
+func init() {
+	inputs.Add("fluentd", func() telegraf.Input { return &Fluentd{} })
+}