Support Processor & Aggregator Plugins

closes #1726

plugins/processors/all/all.go

@@ -0,0 +1,5 @@
+package all
+
+import (
+	_ "github.com/influxdata/telegraf/plugins/processors/printer"
+)

plugins/processors/printer/printer.go

@@ -0,0 +1,35 @@
+package printer
+
+import (
+	"fmt"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/processors"
+)
+
+type Printer struct {
+}
+
+var sampleConfig = `
+`
+
+func (p *Printer) SampleConfig() string {
+	return sampleConfig
+}
+
+func (p *Printer) Description() string {
+	return "Print all metrics that pass through this filter."
+}
+
+func (p *Printer) Apply(in ...telegraf.Metric) []telegraf.Metric {
+	for _, metric := range in {
+		fmt.Println(metric.String())
+	}
+	return in
+}
+
+func init() {
+	processors.Add("printer", func() telegraf.Processor {
+		return &Printer{}
+	})
+}

plugins/processors/registry.go

@@ -0,0 +1,11 @@
+package processors
+
+import "github.com/influxdata/telegraf"
+
+type Creator func() telegraf.Processor
+
+var Processors = map[string]Creator{}
+
+func Add(name string, creator Creator) {
+	Processors[name] = creator
+}