Add option to save retention policy as tag in influxdb_listener (#7356)

plugins/inputs/influxdb_listener/README.md

@@ -54,6 +54,10 @@ submits data to InfluxDB determines the destination database.
   ## the tag will be overwritten with the database supplied.
   # database_tag = ""
 
+  ## If set the retention policy specified in the write query will be added as
+  ## the value of this tag name.
+  # retention_policy_tag = ""
+
   ## Optional username and password to accept for HTTP basic authentication.
   ## You probably want to make sure you have TLS configured above for this.
   # basic_username = "foobar"

plugins/inputs/influxdb_listener/influxdb_listener.go

@@ -29,13 +29,14 @@ type InfluxDBListener struct {
 	port           int
 	tlsint.ServerConfig
 
-	ReadTimeout   internal.Duration `toml:"read_timeout"`
-	WriteTimeout  internal.Duration `toml:"write_timeout"`
-	MaxBodySize   internal.Size     `toml:"max_body_size"`
-	MaxLineSize   internal.Size     `toml:"max_line_size"` // deprecated in 1.14; ignored
-	BasicUsername string            `toml:"basic_username"`
-	BasicPassword string            `toml:"basic_password"`
-	DatabaseTag   string            `toml:"database_tag"`
+	ReadTimeout        internal.Duration `toml:"read_timeout"`
+	WriteTimeout       internal.Duration `toml:"write_timeout"`
+	MaxBodySize        internal.Size     `toml:"max_body_size"`
+	MaxLineSize        internal.Size     `toml:"max_line_size"` // deprecated in 1.14; ignored
+	BasicUsername      string            `toml:"basic_username"`
+	BasicPassword      string            `toml:"basic_password"`
+	DatabaseTag        string            `toml:"database_tag"`
+	RetentionPolicyTag string            `toml:"retention_policy_tag"`
 
 	timeFunc influx.TimeFunc
 
@@ -72,12 +73,16 @@ const sampleConfig = `
   ## 0 means to use the default of 32MiB.
   max_body_size = "32MiB"
 
-  ## Optional tag name used to store the database. 
+  ## Optional tag name used to store the database.
   ## If the write has a database in the query string then it will be kept in this tag name.
   ## This tag can be used in downstream outputs.
   ## The default value of nothing means it will be off and the database will not be recorded.
   # database_tag = ""
 
+  ## If set the retention policy specified in the write query will be added as
+  ## the value of this tag name.
+  # retention_policy_tag = ""
+
   ## Set one or more allowed client CA certificate file names to
   ## enable mutually authenticated TLS connections
   tls_allowed_cacerts = ["/etc/telegraf/clientca.pem"]
@@ -255,6 +260,7 @@ func (h *InfluxDBListener) handleWrite() http.HandlerFunc {
 		}
 
 		db := req.URL.Query().Get("db")
+		rp := req.URL.Query().Get("rp")
 
 		body := req.Body
 		body = http.MaxBytesReader(res, body, h.MaxBodySize.Size)
@@ -316,6 +322,10 @@ func (h *InfluxDBListener) handleWrite() http.HandlerFunc {
 				m.AddTag(h.DatabaseTag, db)
 			}
 
+			if h.RetentionPolicyTag != "" && rp != "" {
+				m.AddTag(h.RetentionPolicyTag, rp)
+			}
+
 			h.acc.AddMetric(m)
 
 		}

plugins/inputs/influxdb_listener/influxdb_listener_test.go

@@ -13,9 +13,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/testutil"
-
 	"github.com/stretchr/testify/require"
 )
 
@@ -207,6 +207,37 @@ func TestWriteKeepDatabase(t *testing.T) {
 	}
 }
 
+func TestWriteRetentionPolicyTag(t *testing.T) {
+	listener := newTestListener()
+	listener.RetentionPolicyTag = "rp"
+
+	acc := &testutil.Accumulator{}
+	require.NoError(t, listener.Init())
+	require.NoError(t, listener.Start(acc))
+	defer listener.Stop()
+
+	resp, err := http.Post(createURL(listener, "http", "/write", "rp=myrp"), "", bytes.NewBuffer([]byte("cpu time_idle=42")))
+	require.NoError(t, err)
+	resp.Body.Close()
+	require.Equal(t, 204, resp.StatusCode)
+
+	expected := []telegraf.Metric{
+		testutil.MustMetric(
+			"cpu",
+			map[string]string{
+				"rp": "myrp",
+			},
+			map[string]interface{}{
+				"time_idle": 42.0,
+			},
+			time.Unix(0, 0),
+		),
+	}
+
+	acc.Wait(1)
+	testutil.RequireMetricsEqual(t, expected, acc.GetTelegrafMetrics(), testutil.IgnoreTime())
+}
+
 // http listener should add a newline at the end of the buffer if it's not there
 func TestWriteNoNewline(t *testing.T) {
 	listener := newTestListener()