Allow exec plugin to parse line-protocol

closes #613

metric.go

@@ -1,6 +1,7 @@
 package telegraf
 
 import (
+	"bytes"
 	"time"
 
 	"github.com/influxdata/influxdb/client/v2"
@@ -68,6 +69,8 @@ func NewMetric(
 // a non-nil error will be returned in addition to the metrics that parsed
 // successfully.
 func ParseMetrics(buf []byte) ([]Metric, error) {
+	// parse even if the buffer begins with a newline
+	buf = bytes.TrimPrefix(buf, []byte("\n"))
 	points, err := models.ParsePoints(buf)
 	metrics := make([]Metric, len(points))
 	for i, point := range points {

plugins/inputs/exec/README.md

@@ -1,28 +1,39 @@
-# Exec Plugin
+# Exec Input Plugin
 
-The exec plugin can execute arbitrary commands which output JSON. Then it flattens JSON and finds
-all numeric values, treating them as floats.
+The exec plugin can execute arbitrary commands which output JSON or
+InfluxDB [line-protocol](https://docs.influxdata.com/influxdb/v0.9/write_protocols/line/).
 
-For example, if you have a json-returning command called mycollector, you could
-setup the exec plugin with:
+If using JSON, only numeric values are parsed and turned into floats. Booleans
+and strings will be ignored.
+
+### Configuration
 
 ```
+# Read flattened metrics from one or more commands that output JSON to stdout
 [[inputs.exec]]
-  command = "/usr/bin/mycollector --output=json"
+  # the command to run
+  command = "/usr/bin/mycollector --foo=bar"
+
+  # Data format to consume. This can be "json" or "influx" (line-protocol)
+  # NOTE json only reads numerical measurements, strings and booleans are ignored.
+  data_format = "json"
+
+  # measurement name suffix (for separating different commands)
   name_suffix = "_mycollector"
-  interval = "10s"
 ```
 
-The name suffix is appended to exec as "exec_name_suffix" to identify the input stream.
+Other options for modifying the measurement names are:
 
-The interval is used to determine how often a particular command should be run. Each
-time the exec plugin runs, it will only run a particular command if it has been at least
-`interval` seconds since the exec plugin last ran the command.
+```
+name_override = "measurement_name"
+name_prefix = "prefix_"
+```
 
+### Example 1
 
-# Sample
+Let's say that we have the above configuration, and mycollector outputs the
+following JSON:
 
-Let's say that we have a command with the name_suffix "_mycollector", which gives the following output:
 ```json
 {
     "a": 0.5,
@@ -33,13 +44,39 @@ Let's say that we have a command with the name_suffix "_mycollector", which give
 }
 ```
 
-The collected metrics will be stored as field values under the same measurement "exec_mycollector":
+The collected metrics will be stored as fields under the measurement
+"exec_mycollector":
+
 ```
- exec_mycollector a=0.5,b_c=0.1,b_d=5 1452815002357578567
+exec_mycollector a=0.5,b_c=0.1,b_d=5 1452815002357578567
 ```
 
-Other options for modifying the measurement names are:
+### Example 2
+
+Now let's say we have the following configuration:
+
 ```
-name_override = "newname"
-name_prefix = "prefix_"
+[[inputs.exec]]
+  # the command to run
+  command = "/usr/bin/line_protocol_collector"
+
+  # Data format to consume. This can be "json" or "influx" (line-protocol)
+  # NOTE json only reads numerical measurements, strings and booleans are ignored.
+  data_format = "influx"
 ```
+
+And line_protocol_collector outputs the following line protocol:
+
+```
+cpu,cpu=cpu0,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu1,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu2,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu3,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu4,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu5,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu6,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+```
+
+You will get data in InfluxDB exactly as it is defined above,
+tags are cpu=cpuN, host=foo, and datacenter=us-east with fields usage_idle
+and usage_busy. They will receive a timestamp at collection time.

plugins/inputs/exec/exec.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os/exec"
+	"time"
 
 	"github.com/gonuts/go-shellquote"
 
@@ -14,18 +15,20 @@ import (
 )
 
 const sampleConfig = `
-  # NOTE This plugin only reads numerical measurements, strings and booleans
-  # will be ignored.
-
   # the command to run
   command = "/usr/bin/mycollector --foo=bar"
 
+  # Data format to consume. This can be "json" or "influx" (line-protocol)
+  # NOTE json only reads numerical measurements, strings and booleans are ignored.
+  data_format = "json"
+
   # measurement name suffix (for separating different commands)
   name_suffix = "_mycollector"
 `
 
 type Exec struct {
-	Command string
+	Command    string
+	DataFormat string
 
 	runner Runner
 }
@@ -71,20 +74,32 @@ func (e *Exec) Gather(acc telegraf.Accumulator) error {
 		return err
 	}
 
-	var jsonOut interface{}
-	err = json.Unmarshal(out, &jsonOut)
-	if err != nil {
-		return fmt.Errorf("exec: unable to parse output of '%s' as JSON, %s",
-			e.Command, err)
-	}
-
-	f := internal.JSONFlattener{}
-	err = f.FlattenJSON("", jsonOut)
-	if err != nil {
+	switch e.DataFormat {
+	case "", "json":
+		var jsonOut interface{}
+		err = json.Unmarshal(out, &jsonOut)
+		if err != nil {
+			return fmt.Errorf("exec: unable to parse output of '%s' as JSON, %s",
+				e.Command, err)
+		}
+
+		f := internal.JSONFlattener{}
+		err = f.FlattenJSON("", jsonOut)
+		if err != nil {
+			return err
+		}
+		acc.AddFields("exec", f.Fields, nil)
+	case "influx":
+		now := time.Now()
+		metrics, err := telegraf.ParseMetrics(out)
+		for _, metric := range metrics {
+			acc.AddFields(metric.Name(), metric.Fields(), metric.Tags(), now)
+		}
 		return err
+	default:
+		return fmt.Errorf("Unsupported data format: %s. Must be either json "+
+			"or influx.", e.DataFormat)
 	}
-
-	acc.AddFields("exec", f.Fields, nil)
 	return nil
 }
 

plugins/inputs/exec/exec_test.go

@@ -31,6 +31,18 @@ const malformedJson = `
     "status": "green",
 `
 
+const lineProtocol = "cpu,host=foo,datacenter=us-east usage_idle=99,usage_busy=1"
+
+const lineProtocolMulti = `
+cpu,cpu=cpu0,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu1,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu2,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu3,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu4,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu5,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+cpu,cpu=cpu6,host=foo,datacenter=us-east usage_idle=99,usage_busy=1
+`
+
 type runnerMock struct {
 	out []byte
 	err error
@@ -97,3 +109,64 @@ func TestCommandError(t *testing.T) {
 	require.Error(t, err)
 	assert.Equal(t, acc.NFields(), 0, "No new points should have been added")
 }
+
+func TestLineProtocolParse(t *testing.T) {
+	e := &Exec{
+		runner:     newRunnerMock([]byte(lineProtocol), nil),
+		Command:    "line-protocol",
+		DataFormat: "influx",
+	}
+
+	var acc testutil.Accumulator
+	err := e.Gather(&acc)
+	require.NoError(t, err)
+
+	fields := map[string]interface{}{
+		"usage_idle": float64(99),
+		"usage_busy": float64(1),
+	}
+	tags := map[string]string{
+		"host":       "foo",
+		"datacenter": "us-east",
+	}
+	acc.AssertContainsTaggedFields(t, "cpu", fields, tags)
+}
+
+func TestLineProtocolParseMultiple(t *testing.T) {
+	e := &Exec{
+		runner:     newRunnerMock([]byte(lineProtocolMulti), nil),
+		Command:    "line-protocol",
+		DataFormat: "influx",
+	}
+
+	var acc testutil.Accumulator
+	err := e.Gather(&acc)
+	require.NoError(t, err)
+
+	fields := map[string]interface{}{
+		"usage_idle": float64(99),
+		"usage_busy": float64(1),
+	}
+	tags := map[string]string{
+		"host":       "foo",
+		"datacenter": "us-east",
+	}
+	cpuTags := []string{"cpu0", "cpu1", "cpu2", "cpu3", "cpu4", "cpu5", "cpu6"}
+
+	for _, cpu := range cpuTags {
+		tags["cpu"] = cpu
+		acc.AssertContainsTaggedFields(t, "cpu", fields, tags)
+	}
+}
+
+func TestInvalidDataFormat(t *testing.T) {
+	e := &Exec{
+		runner:     newRunnerMock([]byte(lineProtocol), nil),
+		Command:    "bad data format",
+		DataFormat: "FooBar",
+	}
+
+	var acc testutil.Accumulator
+	err := e.Gather(&acc)
+	require.Error(t, err)
+}