Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

plugins/parsers/prometheusremotewrite/README.md

@@ -0,0 +1,60 @@
+# Prometheus Remote Write Parser Plugin
+
+Converts prometheus remote write samples directly into Telegraf metrics. It can
+be used with [http_listener_v2](/plugins/inputs/http_listener_v2). There are no
+additional configuration options for Prometheus Remote Write Samples.
+
+## Configuration
+
+```toml
+[[inputs.http_listener_v2]]
+  ## Address and port to host HTTP listener on
+  service_address = ":1234"
+
+  ## Paths to listen to.
+  paths = ["/receive"]
+
+  ## Data format to consume.
+  data_format = "prometheusremotewrite"
+
+  ## Metric version to use, either 1 or 2
+  # metric_version = 2
+```
+
+## Example Input
+
+```json
+prompb.WriteRequest{
+        Timeseries: []*prompb.TimeSeries{
+            {
+                Labels: []*prompb.Label{
+                    {Name: "__name__", Value: "go_gc_duration_seconds"},
+                    {Name: "instance", Value: "localhost:9090"},
+                    {Name: "job", Value: "prometheus"},
+                    {Name: "quantile", Value: "0.99"},
+                },
+                Samples: []prompb.Sample{
+                    {Value: 4.63, Timestamp: time.Date(2020, 4, 1, 0, 0, 0, 0, time.UTC).UnixNano()},
+                },
+            },
+        },
+    }
+
+```
+
+## Example Output (v1)
+
+```text
+go_gc_duration_seconds,instance=localhost:9090,job=prometheus,quantile=0.99 value=4.63 1614889298859000000
+```
+
+## Example Output (v2)
+
+```text
+prometheus_remote_write,instance=localhost:9090,job=prometheus,quantile=0.99 go_gc_duration_seconds=4.63 1614889298859000000
+```
+
+## For alignment with the [InfluxDB v1.x Prometheus Remote Write Spec](https://docs.influxdata.com/influxdb/v1.8/supported_protocols/prometheus/#how-prometheus-metrics-are-parsed-in-influxdb)
+
+- V1: already aligned, it parses metrics according to the spec.
+- V2: Use the [Starlark processor rename prometheus remote write script](https://github.com/influxdata/telegraf/blob/master/plugins/processors/starlark/testdata/rename_prometheus_remote_write.star) to rename the measurement name to the fieldname and rename the fieldname to value.