From ae7ad2230f73dc3942bb55a421f501873ba5fd10 Mon Sep 17 00:00:00 2001
From: Cameron Sparr <cameronsparr@gmail.com>
Date: Thu, 22 Oct 2015 14:24:51 -0600
Subject: [PATCH] Support printing output with usage flag too

---
 cmd/telegraf/telegraf.go |  4 +++-
 config.go                | 21 ++++++++++++++++++---
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/cmd/telegraf/telegraf.go b/cmd/telegraf/telegraf.go
index 19156d072..ceed90eaf 100644
--- a/cmd/telegraf/telegraf.go
+++ b/cmd/telegraf/telegraf.go
@@ -62,7 +62,9 @@ func main() {
 
 	if *fUsage != "" {
 		if err := telegraf.PrintPluginConfig(*fUsage); err != nil {
-			log.Fatal(err)
+			if err2 := telegraf.PrintOutputConfig(*fUsage); err2 != nil {
+				log.Fatalf("%s and %s", err, err2)
+			}
 		}
 		return
 	}
diff --git a/config.go b/config.go
index 60d97f4ff..5f1cbdf96 100644
--- a/config.go
+++ b/config.go
@@ -325,9 +325,14 @@ func PrintSampleConfig(pluginFilters []string, outputFilters []string) {
 	}
 }
 
-func printConfig(name string, plugin plugins.Plugin) {
-	fmt.Printf("\n# %s\n[%s]", plugin.Description(), name)
-	config := plugin.SampleConfig()
+type printer interface {
+	Description() string
+	SampleConfig() string
+}
+
+func printConfig(name string, p printer) {
+	fmt.Printf("\n# %s\n[%s]", p.Description(), name)
+	config := p.SampleConfig()
 	if config == "" {
 		fmt.Printf("\n  # no configuration\n")
 	} else {
@@ -354,6 +359,16 @@ func PrintPluginConfig(name string) error {
 	return nil
 }
 
+// PrintOutputConfig prints the config usage of a single output.
+func PrintOutputConfig(name string) error {
+	if creator, ok := outputs.Outputs[name]; ok {
+		printConfig(name, creator())
+	} else {
+		return errors.New(fmt.Sprintf("Output %s not found", name))
+	}
+	return nil
+}
+
 // Used for fuzzy matching struct field names in FieldByNameFunc calls below
 func fieldMatch(field string) func(string) bool {
 	return func(name string) bool {