Add week number to Elasticsearch output

plugins/outputs/elasticsearch/README.md

@@ -172,6 +172,7 @@ This plugin will format the events in the following way:
   # %m - month (01..12)
   # %d - day of month (e.g., 01)
   # %H - hour (00..23)
+  # %V - week of the year (ISO week) (01..53)
   index_name = "telegraf-%Y.%m.%d" # required.
 
   ## Optional SSL Config
@@ -220,6 +221,6 @@ Integer values collected that are bigger than 2^63 and smaller than 1e21 (or in
 
 ```{"error":{"root_cause":[{"type":"mapper_parsing_exception","reason":"failed to parse"}],"type":"mapper_parsing_exception","reason":"failed to parse","caused_by":{"type":"illegal_state_exception","reason":"No matching token for number_type [BIG_INTEGER]"}},"status":400}```
 
-The correct field mapping will be created on the telegraf index as soon as a supported JSON value is received by Elasticsearch, and subsequent insertions will work because the field mapping will already exist. 
+The correct field mapping will be created on the telegraf index as soon as a supported JSON value is received by Elasticsearch, and subsequent insertions will work because the field mapping will already exist.
 
 This issue is caused by the way Elasticsearch tries to detect integer fields, and by how golang encodes numbers in JSON. There is no clear workaround for this at the moment.

plugins/outputs/elasticsearch/elasticsearch.go

@@ -3,15 +3,16 @@ package elasticsearch
 import (
 	"context"
 	"fmt"
-	"github.com/influxdata/telegraf"
-	"github.com/influxdata/telegraf/internal"
-	"github.com/influxdata/telegraf/plugins/outputs"
-	"gopkg.in/olivere/elastic.v5"
 	"log"
 	"net/http"
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/plugins/outputs"
+	"gopkg.in/olivere/elastic.v5"
 )
 
 type Elasticsearch struct {
@@ -58,6 +59,7 @@ var sampleConfig = `
   # %m - month (01..12)
   # %d - day of month (e.g., 01)
   # %H - hour (00..23)
+  # %V - week of the year (ISO week) (01..53)
   index_name = "telegraf-%Y.%m.%d" # required.
 
   ## Optional SSL Config
@@ -301,6 +303,7 @@ func (a *Elasticsearch) GetIndexName(indexName string, eventTime time.Time) stri
 			"%m", eventTime.UTC().Format("01"),
 			"%d", eventTime.UTC().Format("02"),
 			"%H", eventTime.UTC().Format("15"),
+			"%V", getISOWeek(eventTime.UTC()),
 		)
 
 		indexName = dateReplacer.Replace(indexName)
@@ -310,6 +313,11 @@ func (a *Elasticsearch) GetIndexName(indexName string, eventTime time.Time) stri
 
 }
 
+func getISOWeek(eventTime time.Time) string {
+	_, week := eventTime.ISOWeek()
+	return strconv.Itoa(week)
+}
+
 func (a *Elasticsearch) SampleConfig() string {
 	return sampleConfig
 }

plugins/outputs/elasticsearch/elasticsearch_test.go

@@ -120,6 +120,11 @@ func TestGetIndexName(t *testing.T) {
 			"indexname-%y-%m",
 			"indexname-14-12",
 		},
+		{
+			time.Date(2014, 12, 01, 23, 30, 00, 00, time.UTC),
+			"indexname-%Y-%V",
+			"indexname-2014-49",
+		},
 	}
 	for _, test := range tests {
 		indexName := e.GetIndexName(test.IndexName, test.EventTime)