From 885b2bb641a4d2cc687dc2c84e17161b36722ef3 Mon Sep 17 00:00:00 2001
From: boernd <boernd@users.noreply.github.com>
Date: Wed, 13 Jun 2018 23:06:21 +0200
Subject: [PATCH] Get prometheus remote write version from header (#4)

---
 README.md                |  5 -----
 config/config.go         |  2 --
 prometheus/prometheus.go | 26 +++++++++++++++++++-------
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/README.md b/README.md
index 17bcbe03..6366543d 100644
--- a/README.md
+++ b/README.md
@@ -8,11 +8,6 @@ Example Prometheusbeat configuration:
 prometheusbeat:
   listen: ":8080"
   context: "/prometheus"
-  # The storage request format had a breaking change starting with Prometheus 1.7.
-  # Set the version accordingly.
-  # 1: Prometheus < 1.7
-  # 2: Prometheus >= 1.7
-  version: 2
 
 [...]
 ```
diff --git a/config/config.go b/config/config.go
index fca3220d..05cbd88f 100644
--- a/config/config.go
+++ b/config/config.go
@@ -6,11 +6,9 @@ package config
 type Config struct {
 	Listen  string `config:"listen"`
 	Context string `config:"context"`
-	Version int    `config:"version`
 }
 
 var DefaultConfig = Config{
 	Listen:  ":8080",
 	Context: "/prometheus",
-	Version: 2,
 }
diff --git a/prometheus/prometheus.go b/prometheus/prometheus.go
index 5b62b7e5..e46ed372 100644
--- a/prometheus/prometheus.go
+++ b/prometheus/prometheus.go
@@ -7,14 +7,14 @@ import (
 	"net/http"
 	"strings"
 
-	"github.com/elastic/beats/libbeat/common"
-
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/snappy"
 
-	"github.com/prometheus/prometheus/prompb"
-
+	"github.com/elastic/beats/libbeat/common"
+	"github.com/elastic/beats/libbeat/logp"
+	version "github.com/hashicorp/go-version"
 	"github.com/infonova/prometheusbeat/config"
+	"github.com/prometheus/prometheus/prompb"
 )
 
 type PrometheusServer struct {
@@ -39,10 +39,22 @@ func (promSrv *PrometheusServer) Start(events chan common.MapStr) {
 
 func (promSrv *PrometheusServer) handlePrometheus(w http.ResponseWriter, r *http.Request) {
 
+	v := r.Header.Get("X-Prometheus-Remote-Write-Version")
+	//No header indicates old prometheus version
+	if len(v) == 0 {
+		v = "0.0.0"
+	}
+
+	baseVer, _ := version.NewVersion("0.1.0")
+	reqVer, err := version.NewVersion(v)
+	if err != nil {
+		logp.Err(strings.Join([]string{"wrong prometheus remote write version:", v}, " "))
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
 	var reqBuf []byte
-	var err error
-	// Handle breaking change between Prometheus versions
-	if promSrv.config.Version == 1 {
+	if reqVer.LessThan(baseVer) {
 		reqBuf, err = ioutil.ReadAll(snappy.NewReader(r.Body))
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)