From 885bf273a929e1f92f242f75dc27749b193e3a90 Mon Sep 17 00:00:00 2001
From: Helen Weller <38860767+helenosheaa@users.noreply.github.com>
Date: Wed, 31 Mar 2021 15:08:34 -0400
Subject: [PATCH] Starlark script for renaming prometheus remote write metrics 
 (#9074)

---
 plugins/parsers/prometheusremotewrite/README.md  | 10 ++++++----
 plugins/processors/starlark/README.md            |  1 +
 .../testdata/rename_prometheus_remote_write.star | 16 ++++++++++++++++
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 plugins/processors/starlark/testdata/rename_prometheus_remote_write.star

diff --git a/plugins/parsers/prometheusremotewrite/README.md b/plugins/parsers/prometheusremotewrite/README.md
index 1bad5bd6004ea..b523174e9184a 100644
--- a/plugins/parsers/prometheusremotewrite/README.md
+++ b/plugins/parsers/prometheusremotewrite/README.md
@@ -16,9 +16,7 @@ Converts prometheus remote write samples directly into Telegraf metrics. It can
   data_format = "prometheusremotewrite"
 ```
 
-### Example
-
-**Example Input**
+### Example Input
 ```
 prompb.WriteRequest{
 		Timeseries: []*prompb.TimeSeries{
@@ -38,7 +36,11 @@ prompb.WriteRequest{
 
 ```
 
-**Example Output**
+### Example Output
 ```
 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)**
+
+- 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. 
\ No newline at end of file
diff --git a/plugins/processors/starlark/README.md b/plugins/processors/starlark/README.md
index 62b5b85e766d4..e30ea506c13f7 100644
--- a/plugins/processors/starlark/README.md
+++ b/plugins/processors/starlark/README.md
@@ -237,6 +237,7 @@ def apply(metric):
 - [multiple metrics from json array](/plugins/processors/starlark/testdata/multiple_metrics_with_json.star) - Builds a new metric from each element of a json array then returns all the created metrics.
 - [custom error](/plugins/processors/starlark/testdata/fail.star) - Return a custom error with [fail](https://docs.bazel.build/versions/master/skylark/lib/globals.html#fail).
 - [compare with previous metric](/plugins/processors/starlark/testdata/compare_metrics.star) - Compare the current metric with the previous one using the shared state.
+- [rename prometheus remote write](/plugins/processors/starlark/testdata/rename_prometheus_remote_write.star) - Rename prometheus remote write measurement name with fieldname and rename fieldname to value.
 
 [All examples](/plugins/processors/starlark/testdata) are in the testdata folder.
 
diff --git a/plugins/processors/starlark/testdata/rename_prometheus_remote_write.star b/plugins/processors/starlark/testdata/rename_prometheus_remote_write.star
new file mode 100644
index 0000000000000..cee49196c48ff
--- /dev/null
+++ b/plugins/processors/starlark/testdata/rename_prometheus_remote_write.star
@@ -0,0 +1,16 @@
+# Specifically for prometheus remote write - renames the measurement name to the fieldname. Renames the fieldname to value. 
+# Assumes there is only one field as is the case for prometheus remote write. 
+#
+# Example Input:
+# prometheus_remote_write,instance=localhost:9090,job=prometheus,quantile=0.99 go_gc_duration_seconds=4.63 1614889298859000000
+#
+# Example Output:
+# go_gc_duration_seconds,instance=localhost:9090,job=prometheus,quantile=0.99 value=4.63 1614889299000000000
+
+def apply(metric):
+   if metric.name == "prometheus_remote_write":
+        for k, v in metric.fields.items():
+            metric.name = k
+            metric.fields["value"] = v
+            metric.fields.pop(k)
+   return metric
\ No newline at end of file