Add formdata parser (#5749)

plugins/inputs/http_listener_v2/README.md

@@ -1,7 +1,7 @@
 # HTTP Listener v2 Input Plugin
 
 HTTP Listener v2 is a service input plugin that listens for metrics sent via
-HTTP.  Metrics may be sent in any supported [data format][data_format].
+HTTP. Metrics may be sent in any supported [data format][data_format].
 
 **Note:** The plugin previously known as `http_listener` has been renamed
 `influxdb_listener`.  If you would like Telegraf to act as a proxy/relay for
@@ -49,11 +49,17 @@ This is a sample configuration for the plugin.
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
   data_format = "influx"
+
+  ## Part of the request to consume.
+  ## Available options are "body" and "query".
+  ## Note that the data source and data format are independent properties.
+  ## To consume standard query params and POST forms - use "formdata" as a data_format.
+  # data_source = "body"
 ```
 
 ### Metrics:
 
-Metrics are created from the request body and are dependant on the value of `data_format`.
+Metrics are collected from the part of the request specified by the `data_source` param and are parsed depending on the value of `data_format`.
 
 ### Troubleshooting:
 
@@ -67,5 +73,10 @@ curl -i -XPOST 'http://localhost:8080/telegraf' --data-binary 'cpu_load_short,ho
 curl -i -XPOST 'http://localhost:8080/telegraf' --data-binary '{"value1": 42, "value2": 42}'
 ```
 
+**Send query params**
+```
+curl -i -XGET 'http://localhost:8080/telegraf?host=server01&value=0.42'
+```
+
 [data_format]: /docs/DATA_FORMATS_INPUT.md
 [influxdb_listener]: /plugins/inputs/influxdb_listener/README.md

plugins/inputs/http_listener_v2/http_listener_v2.go

@@ -8,6 +8,8 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/url"
+	"strings"
 	"sync"
 	"time"
 
@@ -23,16 +25,25 @@ import (
 // 500 MB
 const defaultMaxBodySize = 500 * 1024 * 1024
 
+const (
+	body  = "body"
+	query = "query"
+)
+
+// TimeFunc provides a timestamp for the metrics
 type TimeFunc func() time.Time
 
+// HTTPListenerV2 is an input plugin that collects external metrics sent via HTTP
 type HTTPListenerV2 struct {
 	ServiceAddress string
 	Path           string
 	Methods        []string
-	ReadTimeout    internal.Duration
-	WriteTimeout   internal.Duration
-	MaxBodySize    internal.Size
-	Port           int
+	DataSource     string
+
+	ReadTimeout  internal.Duration
+	WriteTimeout internal.Duration
+	MaxBodySize  internal.Size
+	Port         int
 
 	tlsint.ServerConfig
 
@@ -86,6 +97,12 @@ const sampleConfig = `
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
   data_format = "influx"
+
+  ## Part of the request to consume.
+  ## Available options are "body" and "query".
+  ## Note that the data source and data format are independent properties.
+  ## To consume standard query params and POST forms - use "formdata" as a data_format.
+  # data_source = "body"
 `
 
 func (h *HTTPListenerV2) SampleConfig() string {
@@ -164,11 +181,13 @@ func (h *HTTPListenerV2) Stop() {
 }
 
 func (h *HTTPListenerV2) ServeHTTP(res http.ResponseWriter, req *http.Request) {
-	if req.URL.Path == h.Path {
-		h.AuthenticateIfSet(h.serveWrite, res, req)
-	} else {
-		h.AuthenticateIfSet(http.NotFound, res, req)
+	handler := h.serveWrite
+
+	if req.URL.Path != h.Path {
+		handler = http.NotFound
 	}
+
+	h.authenticateIfSet(handler, res, req)
 }
 
 func (h *HTTPListenerV2) serveWrite(res http.ResponseWriter, req *http.Request) {
@@ -191,23 +210,17 @@ func (h *HTTPListenerV2) serveWrite(res http.ResponseWriter, req *http.Request)
 		return
 	}
 
-	// Handle gzip request bodies
-	body := req.Body
-	if req.Header.Get("Content-Encoding") == "gzip" {
-		var err error
-		body, err = gzip.NewReader(req.Body)
-		if err != nil {
-			log.Println("D! " + err.Error())
-			badRequest(res)
-			return
-		}
-		defer body.Close()
+	var bytes []byte
+	var ok bool
+
+	switch strings.ToLower(h.DataSource) {
+	case query:
+		bytes, ok = h.collectQuery(res, req)
+	default:
+		bytes, ok = h.collectBody(res, req)
 	}
 
-	body = http.MaxBytesReader(res, body, h.MaxBodySize.Size)
-	bytes, err := ioutil.ReadAll(body)
-	if err != nil {
-		tooLarge(res)
+	if !ok {
 		return
 	}
 
@@ -217,12 +230,52 @@ func (h *HTTPListenerV2) serveWrite(res http.ResponseWriter, req *http.Request)
 		badRequest(res)
 		return
 	}
+
 	for _, m := range metrics {
 		h.acc.AddFields(m.Name(), m.Fields(), m.Tags(), m.Time())
 	}
+
 	res.WriteHeader(http.StatusNoContent)
 }
 
+func (h *HTTPListenerV2) collectBody(res http.ResponseWriter, req *http.Request) ([]byte, bool) {
+	body := req.Body
+
+	// Handle gzip request bodies
+	if req.Header.Get("Content-Encoding") == "gzip" {
+		var err error
+		body, err = gzip.NewReader(req.Body)
+		if err != nil {
+			log.Println("D! " + err.Error())
+			badRequest(res)
+			return nil, false
+		}
+		defer body.Close()
+	}
+
+	body = http.MaxBytesReader(res, body, h.MaxBodySize.Size)
+	bytes, err := ioutil.ReadAll(body)
+	if err != nil {
+		tooLarge(res)
+		return nil, false
+	}
+
+	return bytes, true
+}
+
+func (h *HTTPListenerV2) collectQuery(res http.ResponseWriter, req *http.Request) ([]byte, bool) {
+	rawQuery := req.URL.RawQuery
+
+	query, err := url.QueryUnescape(rawQuery)
+	if err != nil {
+		log.Println("D! " + err.Error())
+		badRequest(res)
+		return nil, false
+	}
+
+	return []byte(query), true
+}
+
 func tooLarge(res http.ResponseWriter) {
 	res.Header().Set("Content-Type", "application/json")
 	res.WriteHeader(http.StatusRequestEntityTooLarge)
@@ -246,7 +299,7 @@ func badRequest(res http.ResponseWriter) {
 	res.Write([]byte(`{"error":"http: bad request"}`))
 }
 
-func (h *HTTPListenerV2) AuthenticateIfSet(handler http.HandlerFunc, res http.ResponseWriter, req *http.Request) {
+func (h *HTTPListenerV2) authenticateIfSet(handler http.HandlerFunc, res http.ResponseWriter, req *http.Request) {
 	if h.BasicUsername != "" && h.BasicPassword != "" {
 		reqUsername, reqPassword, ok := req.BasicAuth()
 		if !ok ||
@@ -269,6 +322,7 @@ func init() {
 			TimeFunc:       time.Now,
 			Path:           "/telegraf",
 			Methods:        []string{"POST", "PUT"},
+			DataSource:     body,
 		}
 	})
 }