Update docs for addition of override processor

CHANGELOG.md

@@ -35,6 +35,10 @@
 - [ipset](./plugins/inputs/ipset/README.md) - Thanks to @sajoupa
 - [nats](./plugins/inputs/nats/README.md) - Thanks to @mjs & @levex
 
+### New Processors
+
+- [override](./plugins/processors/override/README.md) - Thanks to @KarstenSchnitter
+
 ### New Parsers
 
 - [dropwizard](./docs/DATA_FORMATS_INPUT.md#dropwizard) - Thanks to @atzoum
@@ -75,6 +79,7 @@
 - [#3797](https://github.com/influxdata/telegraf/pull/3797): Add sum stat to basicstats aggregator.
 - [#3626](https://github.com/influxdata/telegraf/pull/3626): Add ability to override proxy from environment in http response.
 - [#3853](https://github.com/influxdata/telegraf/pull/3853): Add host to ping timeout log message.
+- [#3773](https://github.com/influxdata/telegraf/pull/3773): Add override processor.
 
 ### Bugfixes
 

README.md

@@ -264,6 +264,7 @@ formats may be used with input plugins supporting the `data_format` option:
 ## Processor Plugins
 
 * [printer](./plugins/processors/printer)
+* [override](./plugins/processors/override)
 
 ## Aggregator Plugins
 

plugins/processors/override/README.md

@@ -8,9 +8,14 @@ supported by input plugins and aggregators:
 * name_suffix
 * tags
 
-All metrics passing through this processor will be modified accordingly. Values
+All metrics passing through this processor will be modified accordingly.
-of *name_override*, *name_prefix*, *name_suffix* and already present *tags* with
+Select the metrics to modify using the standard
-conflicting keys will be overwritten. Absent *tags* will be created.
+[measurement filtering](https://github.com/influxdata/telegraf/blob/master/docs/CONFIGURATION.md#measurement-filtering)
+options.
+
+Values of *name_override*, *name_prefix*, *name_suffix* and already present
+*tags* with conflicting keys will be overwritten. Absent *tags* will be
+created.
 
 Use-case of this plugin encompass ensuring certain tags or naming conventions
 are adhered to irrespective of input plugin configurations, e.g. by
@@ -19,12 +24,14 @@ are adhered to irrespective of input plugin configurations, e.g. by
 ### Configuration:
 
 ```toml
-# Add a global tag to all metrics
+# Apply metric modifications using override semantics.
 [[processors.override]]
-  name_override = "new name_override"
+  ## All modifications on inputs and aggregators can be overridden:
-  name_prefix = "new name_prefix"
+  # name_override = "new_name"
-  name_suffix = ":new name_suffix"
+  # name_prefix = "new_name_prefix"
-  [processors.tags.add]
+  # name_suffix = "new_name_suffix"
-    additional_tag = "tag_value"
+
-    existing_tag = "new tag_value"
+  ## Tags to be added (all values must be strings)
+  # [processors.override.tags]
+  #   additional_tag = "tag_value"
 ```

plugins/processors/override/override.go

@@ -6,17 +6,13 @@ import (
 )
 
 var sampleConfig = `
-## NOTE This processor will override names, name prefixes, name suffixes and
-## values of tags, that are already present in the metric passed through this
-## filter.
-
   ## All modifications on inputs and aggregators can be overridden:
-# name_override = "new name"
+  # name_override = "new_name"
-#	name_prefix = "new name_prefix"
+  # name_prefix = "new_name_prefix"
-#	name_suffix = "new name_suffix"
+  # name_suffix = "new_name_suffix"
 
   ## Tags to be added (all values must be strings)
-# [processors.overide.tags]
+  # [processors.override.tags]
   #   additional_tag = "tag_value"
 `
 
@@ -32,7 +28,7 @@ func (p *Override) SampleConfig() string {
 }
 
 func (p *Override) Description() string {
-	return "Add all configured tags to all metrics that pass through this filter."
+	return "Apply metric modifications using override semantics."
 }
 
 func (p *Override) Apply(in ...telegraf.Metric) []telegraf.Metric {