Add nagios parser for exec input plugin

closes #762

plugins/parsers/nagios/parser.go

@@ -0,0 +1,102 @@
+package nagios
+
+import (
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/influxdata/telegraf"
+)
+
+type NagiosParser struct {
+	MetricName  string
+	DefaultTags map[string]string
+}
+
+// Got from Alignak
+// https://github.com/Alignak-monitoring/alignak/blob/develop/alignak/misc/perfdata.py
+var perfSplitRegExp, _ = regexp.Compile(`([^=]+=\S+)`)
+var nagiosRegExp, _ = regexp.Compile(`^([^=]+)=([\d\.\-\+eE]+)([\w\/%]*);?([\d\.\-\+eE:~@]+)?;?([\d\.\-\+eE:~@]+)?;?([\d\.\-\+eE]+)?;?([\d\.\-\+eE]+)?;?\s*`)
+
+func (p *NagiosParser) ParseLine(line string) (telegraf.Metric, error) {
+	metrics, err := p.Parse([]byte(line))
+	return metrics[0], err
+}
+
+func (p *NagiosParser) SetDefaultTags(tags map[string]string) {
+	p.DefaultTags = tags
+}
+
+//> rta,host=absol,unit=ms critical=6000,min=0,value=0.332,warning=4000 1456374625003628099
+//> pl,host=absol,unit=% critical=90,min=0,value=0,warning=80 1456374625003693967
+
+func (p *NagiosParser) Parse(buf []byte) ([]telegraf.Metric, error) {
+	metrics := make([]telegraf.Metric, 0)
+	// Convert to string
+	out := string(buf)
+	// Prepare output for splitting
+	// Delete escaped pipes
+	out = strings.Replace(out, `\|`, "___PROTECT_PIPE___", -1)
+	// Split lines and get the first one
+	lines := strings.Split(out, "\n")
+	// Split output and perfdatas
+	data_splitted := strings.Split(lines[0], "|")
+	if len(data_splitted) <= 1 {
+		// No pipe == no perf data
+		return nil, nil
+	}
+	// Get perfdatas
+	perfdatas := data_splitted[1]
+	// Add escaped pipes
+	perfdatas = strings.Replace(perfdatas, "___PROTECT_PIPE___", `\|`, -1)
+	// Split perfs
+	unParsedPerfs := perfSplitRegExp.FindAllSubmatch([]byte(perfdatas), -1)
+	// Iterate on all perfs
+	for _, unParsedPerfs := range unParsedPerfs {
+		// Get metrics
+		// Trim perf
+		trimedPerf := strings.Trim(string(unParsedPerfs[0]), " ")
+		// Parse perf
+		perf := nagiosRegExp.FindAllSubmatch([]byte(trimedPerf), -1)
+		// Bad string
+		if len(perf) == 0 {
+			continue
+		}
+		if len(perf[0]) <= 2 {
+			continue
+		}
+		if perf[0][1] == nil || perf[0][2] == nil {
+			continue
+		}
+		fieldName := string(perf[0][1])
+		tags := make(map[string]string)
+		if perf[0][3] != nil {
+			tags["unit"] = string(perf[0][3])
+		}
+		fields := make(map[string]interface{})
+		fields["value"] = perf[0][2]
+		// TODO should we set empty field
+		// if metric if there is no data ?
+		if perf[0][4] != nil {
+			fields["warning"] = perf[0][4]
+		}
+		if perf[0][5] != nil {
+			fields["critical"] = perf[0][5]
+		}
+		if perf[0][6] != nil {
+			fields["min"] = perf[0][6]
+		}
+		if perf[0][7] != nil {
+			fields["max"] = perf[0][7]
+		}
+		// Create metric
+		metric, err := telegraf.NewMetric(fieldName, tags, fields, time.Now().UTC())
+		if err != nil {
+			return nil, err
+		}
+		// Add Metric
+		metrics = append(metrics, metric)
+	}
+
+	return metrics, nil
+}