From ca1325998924cc32d89b525fd78a29d27e5e26fc Mon Sep 17 00:00:00 2001
From: Joshua Powers <powersj@fastmail.com>
Date: Tue, 2 May 2023 05:24:43 -0600
Subject: [PATCH] feat(aggregators.basicstats): Add percentage change (#13118)

---
 plugins/aggregators/basicstats/README.md      |  8 ++++--
 plugins/aggregators/basicstats/basicstats.go  |  7 ++++++
 .../aggregators/basicstats/basicstats_test.go | 25 +++++++++++++++++++
 plugins/aggregators/basicstats/sample.conf    |  2 +-
 4 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/plugins/aggregators/basicstats/README.md b/plugins/aggregators/basicstats/README.md
index e891cef9e..04f46b170 100644
--- a/plugins/aggregators/basicstats/README.md
+++ b/plugins/aggregators/basicstats/README.md
@@ -26,11 +26,14 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   drop_original = false
 
   ## Configures which basic stats to push as fields
-  # stats = ["count","diff","rate","min","max","mean","non_negative_diff","non_negative_rate","stdev","s2","sum","interval"]
+  # stats = ["count","diff","rate","min","max","mean","non_negative_diff","non_negative_rate","percent_change","stdev","s2","sum","interval"]
 ```
 
 - stats
-  - If not specified, then `count`, `min`, `max`, `mean`, `stdev`, and `s2` are aggregated and pushed as fields.  `sum`, `diff` and `non_negative_diff` are not aggregated by default to maintain backwards compatibility.
+  - If not specified, then `count`, `min`, `max`, `mean`, `stdev`, and `s2` are
+  aggregated and pushed as fields.  `sum`, `diff`, `non_negative_diff`,
+  `percent_change` are not aggregated by default to maintain backwards
+  compatibility.
   - If empty array, no stats are aggregated
 
 ## Measurements & Fields
@@ -44,6 +47,7 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   - field1_mean
   - field1_non_negative_diff (non-negative difference)
   - field1_non_negative_rate (non-negative rate per second)
+  - field1_percent_change
   - field1_sum
   - field1_s2 (variance)
   - field1_stdev (standard deviation)
diff --git a/plugins/aggregators/basicstats/basicstats.go b/plugins/aggregators/basicstats/basicstats.go
index 333129652..0341d054b 100644
--- a/plugins/aggregators/basicstats/basicstats.go
+++ b/plugins/aggregators/basicstats/basicstats.go
@@ -33,6 +33,7 @@ type configuredStats struct {
 	nonNegativeDiff bool
 	rate            bool
 	nonNegativeRate bool
+	percentChange   bool
 	interval        bool
 }
 
@@ -191,6 +192,9 @@ func (b *BasicStats) Push(acc telegraf.Accumulator) {
 				if b.statsConfig.rate {
 					fields[k+"_rate"] = v.rate
 				}
+				if b.statsConfig.percentChange {
+					fields[k+"_percent_change"] = v.diff / v.LAST * 100
+				}
 				if b.statsConfig.nonNegativeRate && v.diff >= 0 {
 					fields[k+"_non_negative_rate"] = v.rate
 				}
@@ -235,6 +239,8 @@ func (b *BasicStats) parseStats() *configuredStats {
 			parsed.rate = true
 		case "non_negative_rate":
 			parsed.nonNegativeRate = true
+		case "percent_change":
+			parsed.percentChange = true
 		case "interval":
 			parsed.interval = true
 		default:
@@ -258,6 +264,7 @@ func (b *BasicStats) getConfiguredStats() {
 			nonNegativeDiff: false,
 			rate:            false,
 			nonNegativeRate: false,
+			percentChange:   false,
 		}
 	} else {
 		b.statsConfig = b.parseStats()
diff --git a/plugins/aggregators/basicstats/basicstats_test.go b/plugins/aggregators/basicstats/basicstats_test.go
index 3f0862497..71159879d 100644
--- a/plugins/aggregators/basicstats/basicstats_test.go
+++ b/plugins/aggregators/basicstats/basicstats_test.go
@@ -536,6 +536,31 @@ func TestBasicStatsWithNonNegativeRate(t *testing.T) {
 	}
 	acc.AssertContainsTaggedFields(t, "m1", expectedFields, expectedTags)
 }
+
+func TestBasicStatsWithPctChange(t *testing.T) {
+	aggregator := NewBasicStats()
+	aggregator.Stats = []string{"percent_change"}
+	aggregator.Log = testutil.Logger{}
+	aggregator.getConfiguredStats()
+
+	aggregator.Add(m1)
+	aggregator.Add(m2)
+
+	acc := testutil.Accumulator{}
+	aggregator.Push(&acc)
+	expectedFields := map[string]interface{}{
+		"a_percent_change": float64(0),
+		"b_percent_change": float64(200),
+		"c_percent_change": float64(100),
+		"d_percent_change": float64(200),
+		"g_percent_change": float64(-66.66666666666666),
+	}
+	expectedTags := map[string]string{
+		"foo": "bar",
+	}
+	acc.AssertContainsTaggedFields(t, "m1", expectedFields, expectedTags)
+}
+
 func TestBasicStatsWithInterval(t *testing.T) {
 	aggregator := NewBasicStats()
 	aggregator.Stats = []string{"interval"}
diff --git a/plugins/aggregators/basicstats/sample.conf b/plugins/aggregators/basicstats/sample.conf
index 8c18e6d2f..b4296ec0b 100644
--- a/plugins/aggregators/basicstats/sample.conf
+++ b/plugins/aggregators/basicstats/sample.conf
@@ -8,4 +8,4 @@
   drop_original = false
 
   ## Configures which basic stats to push as fields
-  # stats = ["count","diff","rate","min","max","mean","non_negative_diff","non_negative_rate","stdev","s2","sum","interval"]
+  # stats = ["count","diff","rate","min","max","mean","non_negative_diff","non_negative_rate","percent_change","stdev","s2","sum","interval"]