Chunk metrics upload to avoid HTTP413

Signed-off-by: Knut Ahlers <knut@ahlers.me>

metrics.go

@@ -5,10 +5,12 @@ import (
 	"time"
 
 	influx "github.com/influxdata/influxdb1-client/v2"
+	"github.com/pkg/errors"
 )
 
 const (
 	influxWriteInterval = 10 * time.Second
+	influxChunkSize     = 10000
 )
 
 type metricsSender struct {
@@ -48,7 +50,6 @@ func (m *metricsSender) resetBatch() error {
 	b, err := influx.NewBatchPoints(influx.BatchPointsConfig{
 		Database: m.database,
 	})
-
 	if err != nil {
 		return err
 	}
@@ -61,14 +62,40 @@ func (m *metricsSender) sendLoop() {
 	for range time.Tick(influxWriteInterval) {
 
 		m.batchLock.Lock()
-		if err := m.client.Write(m.batch); err != nil {
-			m.errs <- err
-			m.batchLock.Unlock()
+
+		failedBatch, err := influx.NewBatchPoints(influx.BatchPointsConfig{
+			Database: cfg.InfluxDBName,
+		})
+		if err != nil {
+			m.errs <- errors.Wrap(err, "creating batchpoints")
 			continue
 		}
-		m.resetBatch()
-		m.batchLock.Unlock()
 
+		for i := 0; i < len(m.batch.Points()); i += influxChunkSize {
+			chunk, err := influx.NewBatchPoints(influx.BatchPointsConfig{
+				Database: cfg.InfluxDBName,
+			})
+			if err != nil {
+				m.errs <- errors.Wrap(err, "creating batchpoints")
+				continue
+			}
+
+			end := i + influxChunkSize
+			if end > len(m.batch.Points()) {
+				end = len(m.batch.Points())
+			}
+
+			chunk.AddPoints(m.batch.Points()[i:end])
+
+			if err := m.client.Write(chunk); err != nil {
+				m.errs <- err
+				failedBatch.AddPoints(m.batch.Points()[i:end])
+				continue
+			}
+		}
+
+		m.batch = failedBatch
+		m.batchLock.Unlock()
 	}
 }
 
@@ -79,7 +106,6 @@ func (m *metricsSender) initialize(host, user, pass string) error {
 		Password: pass,
 		Timeout:  2 * time.Second,
 	})
-
 	if err != nil {
 		return err
 	}