fix: Update prometheus parser to be a new style parser plugin (#11440)

config/config.go

@@ -1429,7 +1429,6 @@ func (c *Config) missingTomlField(_ reflect.Type, key string) error {
 		"grok_custom_pattern_files", "grok_custom_patterns", "grok_named_patterns", "grok_patterns",
 		"grok_timezone", "grok_unique_timestamp",
 		"influx_parser_type",
-		"prometheus_ignore_timestamp", // not used anymore?
 		"value_field_name":
 
 	// Serializer options to ignore

plugins/parsers/all/all.go

@@ -12,6 +12,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/parsers/json_v2"
 	_ "github.com/influxdata/telegraf/plugins/parsers/logfmt"
 	_ "github.com/influxdata/telegraf/plugins/parsers/nagios"
+	_ "github.com/influxdata/telegraf/plugins/parsers/prometheus"
 	_ "github.com/influxdata/telegraf/plugins/parsers/value"
 	_ "github.com/influxdata/telegraf/plugins/parsers/wavefront"
 	_ "github.com/influxdata/telegraf/plugins/parsers/xpath"

plugins/parsers/prometheus/parser.go

@@ -16,13 +16,14 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/metric"
+	"github.com/influxdata/telegraf/plugins/parsers"
 	"github.com/influxdata/telegraf/plugins/parsers/prometheus/common"
 )
 
 type Parser struct {
-	DefaultTags     map[string]string
+	DefaultTags     map[string]string `toml:"-"`
-	Header          http.Header
+	Header          http.Header       `toml:"-"` // set by the prometheus input
-	IgnoreTimestamp bool
+	IgnoreTimestamp bool              `toml:"prometheus_ignore_timestamp"`
 }
 
 func (p *Parser) Parse(buf []byte) ([]telegraf.Metric, error) {
@@ -186,3 +187,15 @@ func (p *Parser) GetTimestamp(m *dto.Metric, now time.Time) time.Time {
 	}
 	return t
 }
+
+func (p *Parser) InitFromConfig(config *parsers.Config) error {
+	p.IgnoreTimestamp = config.PrometheusIgnoreTimestamp
+	return nil
+}
+
+func init() {
+	parsers.Add("prometheus",
+		func(defaultMetricName string) telegraf.Parser {
+			return &Parser{}
+		})
+}

plugins/parsers/registry.go

@@ -6,7 +6,6 @@ import (
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/plugins/parsers/influx"
 	"github.com/influxdata/telegraf/plugins/parsers/influx/influx_upstream"
-	"github.com/influxdata/telegraf/plugins/parsers/prometheus"
 	"github.com/influxdata/telegraf/plugins/parsers/prometheusremotewrite"
 	"github.com/influxdata/telegraf/plugins/parsers/temporary/json_v2"
 	"github.com/influxdata/telegraf/plugins/parsers/temporary/xpath"
@@ -202,11 +201,6 @@ func NewParser(config *Config) (Parser, error) {
 		} else {
 			parser, err = NewInfluxParser()
 		}
-	case "prometheus":
-		parser, err = NewPrometheusParser(
-			config.DefaultTags,
-			config.PrometheusIgnoreTimestamp,
-		)
 	case "prometheusremotewrite":
 		parser, err = NewPrometheusRemoteWriteParser(config.DefaultTags)
 	default:
@@ -236,13 +230,6 @@ func NewInfluxUpstreamParser() (Parser, error) {
 	return influx_upstream.NewParser(), nil
 }
 
-func NewPrometheusParser(defaultTags map[string]string, ignoreTimestamp bool) (Parser, error) {
-	return &prometheus.Parser{
-		DefaultTags:     defaultTags,
-		IgnoreTimestamp: ignoreTimestamp,
-	}, nil
-}
-
 func NewPrometheusRemoteWriteParser(defaultTags map[string]string) (Parser, error) {
 	return &prometheusremotewrite.Parser{
 		DefaultTags: defaultTags,