Starlark example dropbytype

plugins/processors/starlark/README.md

@@ -157,6 +157,8 @@ Attempting to modify the global scope will fail with an error.
 
 ### Examples
 
+- [drop string fields](/plugins/processors/starlark/testdata/drop_string_fields.star) - Drop fields containing string values.
+- [drop fields with unexpected type](/plugins/processors/starlark/testdata/drop_fields_with_unexpected_type.star) - Drop fields containing unexpected value types.
 - [json](/plugins/processors/starlark/testdata/json.star) - an example of processing JSON from a field in a metric
 - [number logic](/plugins/processors/starlark/testdata/number_logic.star) - transform a numerical value to another numerical value
 - [pivot](/plugins/processors/starlark/testdata/pivot.star) - Pivots a key's value to be the key for another key.

plugins/processors/starlark/starlark_test.go

@@ -2446,6 +2446,71 @@ func TestScript(t *testing.T) {
  ),
  },
  },
+ {
+ name: "drop fields by type",
+ plugin: &Starlark{
+ Script: "testdata/drop_string_fields.star",
+ Log: testutil.Logger{},
+ },
+ input: []telegraf.Metric{
+ testutil.MustMetric("device",
+ map[string]string{},
+ map[string]interface{}{
+ "a": 42,
+ "b": "42",
+ "c": 42.0,
+ "d": "42.0",
+ "e": true,
+ },
+ time.Unix(0, 0),
+ ),
+ },
+ expected: []telegraf.Metric{
+ testutil.MustMetric("device",
+ map[string]string{},
+ map[string]interface{}{
+ "a": 42,
+ "c": 42.0,
+ "e": true,
+ },
+ time.Unix(0, 0),
+ ),
+ },
+ },
+ {
+ name: "drop fields with unexpected type",
+ plugin: &Starlark{
+ Script: "testdata/drop_fields_with_unexpected_type.star",
+ Log: testutil.Logger{},
+ },
+ input: []telegraf.Metric{
+ testutil.MustMetric("device",
+ map[string]string{},
+ map[string]interface{}{
+ "a": 42,
+ "b": "42",
+ "c": 42.0,
+ "d": "42.0",
+ "e": true,
+ "f": 23.0,
+ },
+ time.Unix(0, 0),
+ ),
+ },
+ expected: []telegraf.Metric{
+ testutil.MustMetric("device",
+ map[string]string{},
+ map[string]interface{}{
+ "a": 42,
+ "c": 42.0,
+ "d": "42.0",
+ "e": true,
+ "f": 23.0,
+ },
+ time.Unix(0, 0),
+ ),
+ },
+ },
  {
  name: "scale",
  plugin: &Starlark{

plugins/processors/starlark/testdata/drop_fields_with_unexpected_type.star

@@ -0,0 +1,26 @@
+# Drop fields if they NOT contain values of an expected type.
+#
+# In this example we ignore fields with an unknown expected type and do not drop them.
+#
+# Example Input:
+# measurement,host=hostname a=1i,b=4.2,c=42.0,d="v3.14",e=true,f=23.0 1597255410000000000
+# measurement,host=hostname a=1i,b="somestring",c=42.0,d="v3.14",e=true,f=23.0 1597255410000000000
+#
+# Example Output:
+# measurement,host=hostname a=1i,b=4.2,c=42.0,d="v3.14",e=true,f=23.0 1597255410000000000
+# measurement,host=hostname a=1i,c=42.0,d="v3.14",e=true,f=23.0 1597255410000000000
+
+expected_type = {
+ "a": "int",
+ "b": "float",
+ "c": "float",
+ "d": "string",
+ "e": "bool"
+}
+
+def apply(metric):
+ for k, v in metric.fields.items():
+ if type(v) != expected_type.get(k, type(v)):
+ metric.fields.pop(k)
+
+ return metric

plugins/processors/starlark/testdata/drop_string_fields.star

@@ -0,0 +1,14 @@
+# Drop fields if they contain a string.
+#
+# Example Input:
+# measurement,host=hostname a=1,b="somestring" 1597255410000000000
+#
+# Example Output:
+# measurement,host=hostname a=1 1597255410000000000
+
+def apply(metric):
+ for k, v in metric.fields.items():
+ if type(v) == "string":
+ metric.fields.pop(k)
+
+ return metric