Add file input plugin and grok parser (#4332)

2018-07-13 23:22:59 -07:00
parent 3f87e5bf57
commit 774a9f0492
24 changed files with 558 additions and 154 deletions
--- a/plugins/parsers/grok/influx_patterns.go
+++ b/plugins/parsers/grok/influx_patterns.go
@@ -0,0 +1,78 @@
+package grok
+
+// DEFAULT_PATTERNS SHOULD BE KEPT IN-SYNC WITH patterns/influx-patterns
+const DEFAULT_PATTERNS = `
+# Captures are a slightly modified version of logstash "grok" patterns, with
+#  the format %{<capture syntax>[:<semantic name>][:<modifier>]}
+# By default all named captures are converted into string fields.
+# Modifiers can be used to convert captures to other types or tags.
+# Timestamp modifiers can be used to convert captures to the timestamp of the
+#  parsed metric.
+
+# View logstash grok pattern docs here:
+#   https://www.elastic.co/guide/en/logstash/current/plugins-filters-grok.html
+# All default logstash patterns are supported, these can be viewed here:
+#   https://github.com/logstash-plugins/logstash-patterns-core/blob/master/patterns/grok-patterns
+
+# Available modifiers:
+#   string   (default if nothing is specified)
+#   int
+#   float
+#   duration (ie, 5.23ms gets converted to int nanoseconds)
+#   tag      (converts the field into a tag)
+#   drop     (drops the field completely)
+# Timestamp modifiers:
+#   ts-ansic         ("Mon Jan _2 15:04:05 2006")
+#   ts-unix          ("Mon Jan _2 15:04:05 MST 2006")
+#   ts-ruby          ("Mon Jan 02 15:04:05 -0700 2006")
+#   ts-rfc822        ("02 Jan 06 15:04 MST")
+#   ts-rfc822z       ("02 Jan 06 15:04 -0700")
+#   ts-rfc850        ("Monday, 02-Jan-06 15:04:05 MST")
+#   ts-rfc1123       ("Mon, 02 Jan 2006 15:04:05 MST")
+#   ts-rfc1123z      ("Mon, 02 Jan 2006 15:04:05 -0700")
+#   ts-rfc3339       ("2006-01-02T15:04:05Z07:00")
+#   ts-rfc3339nano   ("2006-01-02T15:04:05.999999999Z07:00")
+#   ts-httpd         ("02/Jan/2006:15:04:05 -0700")
+#   ts-epoch         (seconds since unix epoch)
+#   ts-epochnano     (nanoseconds since unix epoch)
+#   ts-"CUSTOM"
+# CUSTOM time layouts must be within quotes and be the representation of the
+# "reference time", which is Mon Jan 2 15:04:05 -0700 MST 2006
+# See https://golang.org/pkg/time/#Parse for more details.
+
+# Example log file pattern, example log looks like this:
+#   [04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs
+# Breakdown of the DURATION pattern below:
+#   NUMBER  is a builtin logstash grok pattern matching float & int numbers.
+#   [nuµm]? is a regex specifying 0 or 1 of the characters within brackets.
+#   s       is also regex, this pattern must end in "s".
+# so DURATION will match something like '5.324ms' or '6.1µs' or '10s'
+DURATION %{NUMBER}[nuµm]?s
+RESPONSE_CODE %{NUMBER:response_code:tag}
+RESPONSE_TIME %{DURATION:response_time_ns:duration}
+EXAMPLE_LOG \[%{HTTPDATE:ts:ts-httpd}\] %{NUMBER:myfloat:float} %{RESPONSE_CODE} %{IPORHOST:clientip} %{RESPONSE_TIME}
+
+# Wider-ranging username matching vs. logstash built-in %{USER}
+NGUSERNAME [a-zA-Z0-9\.\@\-\+_%]+
+NGUSER %{NGUSERNAME}
+# Wider-ranging client IP matching
+CLIENT (?:%{IPV6}|%{IPV4}|%{HOSTNAME}|%{HOSTPORT})
+
+##
+## COMMON LOG PATTERNS
+##
+
+# apache & nginx logs, this is also known as the "common log format"
+#   see https://en.wikipedia.org/wiki/Common_Log_Format
+COMMON_LOG_FORMAT %{CLIENT:client_ip} %{NOTSPACE:ident} %{NOTSPACE:auth} \[%{HTTPDATE:ts:ts-httpd}\] "(?:%{WORD:verb:tag} %{NOTSPACE:request}(?: HTTP/%{NUMBER:http_version:float})?|%{DATA})" %{NUMBER:resp_code:tag} (?:%{NUMBER:resp_bytes:int}|-)
+
+# Combined log format is the same as the common log format but with the addition
+# of two quoted strings at the end for "referrer" and "agent"
+#   See Examples at http://httpd.apache.org/docs/current/mod/mod_log_config.html
+COMBINED_LOG_FORMAT %{COMMON_LOG_FORMAT} %{QS:referrer} %{QS:agent}
+
+# HTTPD log formats
+HTTPD20_ERRORLOG \[%{HTTPDERROR_DATE:timestamp}\] \[%{LOGLEVEL:loglevel:tag}\] (?:\[client %{IPORHOST:clientip}\] ){0,1}%{GREEDYDATA:errormsg}
+HTTPD24_ERRORLOG \[%{HTTPDERROR_DATE:timestamp}\] \[%{WORD:module}:%{LOGLEVEL:loglevel:tag}\] \[pid %{POSINT:pid:int}:tid %{NUMBER:tid:int}\]( \(%{POSINT:proxy_errorcode:int}\)%{DATA:proxy_errormessage}:)?( \[client %{IPORHOST:client}:%{POSINT:clientport}\])? %{DATA:errorcode}: %{GREEDYDATA:message}
+HTTPD_ERRORLOG %{HTTPD20_ERRORLOG}|%{HTTPD24_ERRORLOG}
+`
--- a/plugins/parsers/grok/parser.go
+++ b/plugins/parsers/grok/parser.go
@@ -0,0 +1,535 @@
+package grok
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/vjeantet/grok"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/metric"
+)
+
+var timeLayouts = map[string]string{
+	"ts-ansic":       "Mon Jan _2 15:04:05 2006",
+	"ts-unix":        "Mon Jan _2 15:04:05 MST 2006",
+	"ts-ruby":        "Mon Jan 02 15:04:05 -0700 2006",
+	"ts-rfc822":      "02 Jan 06 15:04 MST",
+	"ts-rfc822z":     "02 Jan 06 15:04 -0700", // RFC822 with numeric zone
+	"ts-rfc850":      "Monday, 02-Jan-06 15:04:05 MST",
+	"ts-rfc1123":     "Mon, 02 Jan 2006 15:04:05 MST",
+	"ts-rfc1123z":    "Mon, 02 Jan 2006 15:04:05 -0700", // RFC1123 with numeric zone
+	"ts-rfc3339":     "2006-01-02T15:04:05Z07:00",
+	"ts-rfc3339nano": "2006-01-02T15:04:05.999999999Z07:00",
+	"ts-httpd":       "02/Jan/2006:15:04:05 -0700",
+	// These three are not exactly "layouts", but they are special cases that
+	// will get handled in the ParseLine function.
+	"ts-epoch":     "EPOCH",
+	"ts-epochnano": "EPOCH_NANO",
+	"ts-syslog":    "SYSLOG_TIMESTAMP",
+	"ts":           "GENERIC_TIMESTAMP", // try parsing all known timestamp layouts.
+}
+
+const (
+	INT               = "int"
+	TAG               = "tag"
+	FLOAT             = "float"
+	STRING            = "string"
+	DURATION          = "duration"
+	DROP              = "drop"
+	EPOCH             = "EPOCH"
+	EPOCH_NANO        = "EPOCH_NANO"
+	SYSLOG_TIMESTAMP  = "SYSLOG_TIMESTAMP"
+	GENERIC_TIMESTAMP = "GENERIC_TIMESTAMP"
+)
+
+var (
+	// matches named captures that contain a modifier.
+	//   ie,
+	//     %{NUMBER:bytes:int}
+	//     %{IPORHOST:clientip:tag}
+	//     %{HTTPDATE:ts1:ts-http}
+	//     %{HTTPDATE:ts2:ts-"02 Jan 06 15:04"}
+	modifierRe = regexp.MustCompile(`%{\w+:(\w+):(ts-".+"|t?s?-?\w+)}`)
+	// matches a plain pattern name. ie, %{NUMBER}
+	patternOnlyRe = regexp.MustCompile(`%{(\w+)}`)
+)
+
+// Parser is the primary struct to handle and grok-patterns defined in the config toml
+type Parser struct {
+	Patterns []string
+	// namedPatterns is a list of internally-assigned names to the patterns
+	// specified by the user in Patterns.
+	// They will look like:
+	//   GROK_INTERNAL_PATTERN_0, GROK_INTERNAL_PATTERN_1, etc.
+	NamedPatterns      []string
+	CustomPatterns     string
+	CustomPatternFiles []string
+	Measurement        string
+	DefaultTags        map[string]string
+
+	// Timezone is an optional component to help render log dates to
+	// your chosen zone.
+	// Default: "" which renders UTC
+	// Options are as follows:
+	// 1. Local             -- interpret based on machine localtime
+	// 2. "America/Chicago" -- Unix TZ values like those found in https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
+	// 3. UTC               -- or blank/unspecified, will return timestamp in UTC
+	Timezone string
+	loc      *time.Location
+
+	// typeMap is a map of patterns -> capture name -> modifier,
+	//   ie, {
+	//          "%{TESTLOG}":
+	//             {
+	//                "bytes": "int",
+	//                "clientip": "tag"
+	//             }
+	//       }
+	typeMap map[string]map[string]string
+	// tsMap is a map of patterns -> capture name -> timestamp layout.
+	//   ie, {
+	//          "%{TESTLOG}":
+	//             {
+	//                "httptime": "02/Jan/2006:15:04:05 -0700"
+	//             }
+	//       }
+	tsMap map[string]map[string]string
+	// patterns is a map of all of the parsed patterns from CustomPatterns
+	// and CustomPatternFiles.
+	//   ie, {
+	//          "DURATION":      "%{NUMBER}[nuµm]?s"
+	//          "RESPONSE_CODE": "%{NUMBER:rc:tag}"
+	//       }
+	patterns map[string]string
+	// foundTsLayouts is a slice of timestamp patterns that have been found
+	// in the log lines. This slice gets updated if the user uses the generic
+	// 'ts' modifier for timestamps. This slice is checked first for matches,
+	// so that previously-matched layouts get priority over all other timestamp
+	// layouts.
+	foundTsLayouts []string
+
+	timeFunc func() time.Time
+	g        *grok.Grok
+	tsModder *tsModder
+}
+
+// Compile is a bound method to Parser which will process the options for our parser
+func (p *Parser) Compile() error {
+	p.typeMap = make(map[string]map[string]string)
+	p.tsMap = make(map[string]map[string]string)
+	p.patterns = make(map[string]string)
+	p.tsModder = &tsModder{}
+	var err error
+	p.g, err = grok.NewWithConfig(&grok.Config{NamedCapturesOnly: true})
+	if err != nil {
+		return err
+	}
+
+	// Give Patterns fake names so that they can be treated as named
+	// "custom patterns"
+	p.NamedPatterns = make([]string, 0, len(p.Patterns))
+	for i, pattern := range p.Patterns {
+		pattern = strings.TrimSpace(pattern)
+		if pattern == "" {
+			continue
+		}
+		name := fmt.Sprintf("GROK_INTERNAL_PATTERN_%d", i)
+		p.CustomPatterns += "\n" + name + " " + pattern + "\n"
+		p.NamedPatterns = append(p.NamedPatterns, "%{"+name+"}")
+	}
+
+	if len(p.NamedPatterns) == 0 {
+		return fmt.Errorf("pattern required")
+	}
+
+	// Combine user-supplied CustomPatterns with DEFAULT_PATTERNS and parse
+	// them together as the same type of pattern.
+	p.CustomPatterns = DEFAULT_PATTERNS + p.CustomPatterns
+	if len(p.CustomPatterns) != 0 {
+		scanner := bufio.NewScanner(strings.NewReader(p.CustomPatterns))
+		p.addCustomPatterns(scanner)
+	}
+
+	// Parse any custom pattern files supplied.
+	for _, filename := range p.CustomPatternFiles {
+		file, fileErr := os.Open(filename)
+		if fileErr != nil {
+			return fileErr
+		}
+
+		scanner := bufio.NewScanner(bufio.NewReader(file))
+		p.addCustomPatterns(scanner)
+	}
+
+	p.loc, err = time.LoadLocation(p.Timezone)
+	if err != nil {
+		log.Printf("W! improper timezone supplied (%s), setting loc to UTC", p.Timezone)
+		p.loc, _ = time.LoadLocation("UTC")
+	}
+
+	if p.timeFunc == nil {
+		p.timeFunc = time.Now
+	}
+
+	return p.compileCustomPatterns()
+}
+
+// ParseLine is the primary function to process individual lines, returning the metrics
+func (p *Parser) ParseLine(line string) (telegraf.Metric, error) {
+	var err error
+	// values are the parsed fields from the log line
+	var values map[string]string
+	// the matching pattern string
+	var patternName string
+	for _, pattern := range p.NamedPatterns {
+		if values, err = p.g.Parse(pattern, line); err != nil {
+			return nil, err
+		}
+		if len(values) != 0 {
+			patternName = pattern
+			break
+		}
+	}
+
+	if len(values) == 0 {
+		log.Printf("D! Grok no match found for: %q", line)
+		return nil, nil
+	}
+
+	fields := make(map[string]interface{})
+	tags := make(map[string]string)
+
+	//add default tags
+	for k, v := range p.DefaultTags {
+		tags[k] = v
+	}
+
+	timestamp := time.Now()
+	for k, v := range values {
+		if k == "" || v == "" {
+			continue
+		}
+
+		// t is the modifier of the field
+		var t string
+		// check if pattern has some modifiers
+		if types, ok := p.typeMap[patternName]; ok {
+			t = types[k]
+		}
+		// if we didn't find a modifier, check if we have a timestamp layout
+		if t == "" {
+			if ts, ok := p.tsMap[patternName]; ok {
+				// check if the modifier is a timestamp layout
+				if layout, ok := ts[k]; ok {
+					t = layout
+				}
+			}
+		}
+		// if we didn't find a type OR timestamp modifier, assume string
+		if t == "" {
+			t = STRING
+		}
+
+		switch t {
+		case INT:
+			iv, err := strconv.ParseInt(v, 10, 64)
+			if err != nil {
+				log.Printf("E! Error parsing %s to int: %s", v, err)
+			} else {
+				fields[k] = iv
+			}
+		case FLOAT:
+			fv, err := strconv.ParseFloat(v, 64)
+			if err != nil {
+				log.Printf("E! Error parsing %s to float: %s", v, err)
+			} else {
+				fields[k] = fv
+			}
+		case DURATION:
+			d, err := time.ParseDuration(v)
+			if err != nil {
+				log.Printf("E! Error parsing %s to duration: %s", v, err)
+			} else {
+				fields[k] = int64(d)
+			}
+		case TAG:
+			tags[k] = v
+		case STRING:
+			fields[k] = strings.Trim(v, `"`)
+		case EPOCH:
+			parts := strings.SplitN(v, ".", 2)
+			if len(parts) == 0 {
+				log.Printf("E! Error parsing %s to timestamp: %s", v, err)
+				break
+			}
+
+			sec, err := strconv.ParseInt(parts[0], 10, 64)
+			if err != nil {
+				log.Printf("E! Error parsing %s to timestamp: %s", v, err)
+				break
+			}
+			ts := time.Unix(sec, 0)
+
+			if len(parts) == 2 {
+				padded := fmt.Sprintf("%-9s", parts[1])
+				nsString := strings.Replace(padded[:9], " ", "0", -1)
+				nanosec, err := strconv.ParseInt(nsString, 10, 64)
+				if err != nil {
+					log.Printf("E! Error parsing %s to timestamp: %s", v, err)
+					break
+				}
+				ts = ts.Add(time.Duration(nanosec) * time.Nanosecond)
+			}
+			timestamp = ts
+		case EPOCH_NANO:
+			iv, err := strconv.ParseInt(v, 10, 64)
+			if err != nil {
+				log.Printf("E! Error parsing %s to int: %s", v, err)
+			} else {
+				timestamp = time.Unix(0, iv)
+			}
+		case SYSLOG_TIMESTAMP:
+			ts, err := time.ParseInLocation(time.Stamp, v, p.loc)
+			if err == nil {
+				if ts.Year() == 0 {
+					ts = ts.AddDate(timestamp.Year(), 0, 0)
+				}
+				timestamp = ts
+			} else {
+				log.Printf("E! Error parsing %s to time layout [%s]: %s", v, t, err)
+			}
+		case GENERIC_TIMESTAMP:
+			var foundTs bool
+			// first try timestamp layouts that we've already found
+			for _, layout := range p.foundTsLayouts {
+				ts, err := time.ParseInLocation(layout, v, p.loc)
+				if err == nil {
+					timestamp = ts
+					foundTs = true
+					break
+				}
+			}
+			// if we haven't found a timestamp layout yet, try all timestamp
+			// layouts.
+			if !foundTs {
+				for _, layout := range timeLayouts {
+					ts, err := time.ParseInLocation(layout, v, p.loc)
+					if err == nil {
+						timestamp = ts
+						foundTs = true
+						p.foundTsLayouts = append(p.foundTsLayouts, layout)
+						break
+					}
+				}
+			}
+			// if we still haven't found a timestamp layout, log it and we will
+			// just use time.Now()
+			if !foundTs {
+				log.Printf("E! Error parsing timestamp [%s], could not find any "+
+					"suitable time layouts.", v)
+			}
+		case DROP:
+		// goodbye!
+		default:
+			v = strings.Replace(v, ",", ".", -1)
+			ts, err := time.ParseInLocation(t, v, p.loc)
+			if err == nil {
+				timestamp = ts
+			} else {
+				log.Printf("E! Error parsing %s to time layout [%s]: %s", v, t, err)
+			}
+		}
+	}
+
+	if len(fields) == 0 {
+		return nil, fmt.Errorf("logparser_grok: must have one or more fields")
+	}
+
+	return metric.New(p.Measurement, tags, fields, p.tsModder.tsMod(timestamp))
+}
+
+func (p *Parser) Parse(buf []byte) ([]telegraf.Metric, error) {
+	scanner := bufio.NewScanner(strings.NewReader(string(buf)))
+	var lines []string
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+	var metrics []telegraf.Metric
+
+	for _, line := range lines {
+		m, err := p.ParseLine(line)
+		if err != nil {
+			return nil, err
+		}
+		metrics = append(metrics, m)
+	}
+
+	return metrics, nil
+}
+
+func (p *Parser) SetDefaultTags(tags map[string]string) {
+	p.DefaultTags = tags
+}
+
+func (p *Parser) addCustomPatterns(scanner *bufio.Scanner) {
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if len(line) > 0 && line[0] != '#' {
+			names := strings.SplitN(line, " ", 2)
+			p.patterns[names[0]] = names[1]
+		}
+	}
+}
+
+func (p *Parser) compileCustomPatterns() error {
+	var err error
+	// check if the pattern contains a subpattern that is already defined
+	// replace it with the subpattern for modifier inheritance.
+	for i := 0; i < 2; i++ {
+		for name, pattern := range p.patterns {
+			subNames := patternOnlyRe.FindAllStringSubmatch(pattern, -1)
+			for _, subName := range subNames {
+				if subPattern, ok := p.patterns[subName[1]]; ok {
+					pattern = strings.Replace(pattern, subName[0], subPattern, 1)
+				}
+			}
+			p.patterns[name] = pattern
+		}
+	}
+
+	// check if pattern contains modifiers. Parse them out if it does.
+	for name, pattern := range p.patterns {
+		if modifierRe.MatchString(pattern) {
+			// this pattern has modifiers, so parse out the modifiers
+			pattern, err = p.parseTypedCaptures(name, pattern)
+			if err != nil {
+				return err
+			}
+			p.patterns[name] = pattern
+		}
+	}
+
+	return p.g.AddPatternsFromMap(p.patterns)
+}
+
+// parseTypedCaptures parses the capture modifiers, and then deletes the
+// modifier from the line so that it is a valid "grok" pattern again.
+//   ie,
+//     %{NUMBER:bytes:int}      => %{NUMBER:bytes}      (stores %{NUMBER}->bytes->int)
+//     %{IPORHOST:clientip:tag} => %{IPORHOST:clientip} (stores %{IPORHOST}->clientip->tag)
+func (p *Parser) parseTypedCaptures(name, pattern string) (string, error) {
+	matches := modifierRe.FindAllStringSubmatch(pattern, -1)
+
+	// grab the name of the capture pattern
+	patternName := "%{" + name + "}"
+	// create type map for this pattern
+	p.typeMap[patternName] = make(map[string]string)
+	p.tsMap[patternName] = make(map[string]string)
+
+	// boolean to verify that each pattern only has a single ts- data type.
+	hasTimestamp := false
+	for _, match := range matches {
+		// regex capture 1 is the name of the capture
+		// regex capture 2 is the modifier of the capture
+		if strings.HasPrefix(match[2], "ts") {
+			if hasTimestamp {
+				return pattern, fmt.Errorf("logparser pattern compile error: "+
+					"Each pattern is allowed only one named "+
+					"timestamp data type. pattern: %s", pattern)
+			}
+			if layout, ok := timeLayouts[match[2]]; ok {
+				// built-in time format
+				p.tsMap[patternName][match[1]] = layout
+			} else {
+				// custom time format
+				p.tsMap[patternName][match[1]] = strings.TrimSuffix(strings.TrimPrefix(match[2], `ts-"`), `"`)
+			}
+			hasTimestamp = true
+		} else {
+			p.typeMap[patternName][match[1]] = match[2]
+		}
+
+		// the modifier is not a valid part of a "grok" pattern, so remove it
+		// from the pattern.
+		pattern = strings.Replace(pattern, ":"+match[2]+"}", "}", 1)
+	}
+
+	return pattern, nil
+}
+
+// tsModder is a struct for incrementing identical timestamps of log lines
+// so that we don't push identical metrics that will get overwritten.
+type tsModder struct {
+	dupe     time.Time
+	last     time.Time
+	incr     time.Duration
+	incrn    time.Duration
+	rollover time.Duration
+}
+
+// tsMod increments the given timestamp one unit more from the previous
+// duplicate timestamp.
+// the increment unit is determined as the next smallest time unit below the
+// most significant time unit of ts.
+//   ie, if the input is at ms precision, it will increment it 1µs.
+func (t *tsModder) tsMod(ts time.Time) time.Time {
+	defer func() { t.last = ts }()
+	// don't mod the time if we don't need to
+	if t.last.IsZero() || ts.IsZero() {
+		t.incrn = 0
+		t.rollover = 0
+		return ts
+	}
+	if !ts.Equal(t.last) && !ts.Equal(t.dupe) {
+		t.incr = 0
+		t.incrn = 0
+		t.rollover = 0
+		return ts
+	}
+
+	if ts.Equal(t.last) {
+		t.dupe = ts
+	}
+
+	if ts.Equal(t.dupe) && t.incr == time.Duration(0) {
+		tsNano := ts.UnixNano()
+
+		d := int64(10)
+		counter := 1
+		for {
+			a := tsNano % d
+			if a > 0 {
+				break
+			}
+			d = d * 10
+			counter++
+		}
+
+		switch {
+		case counter <= 6:
+			t.incr = time.Nanosecond
+		case counter <= 9:
+			t.incr = time.Microsecond
+		case counter > 9:
+			t.incr = time.Millisecond
+		}
+	}
+
+	t.incrn++
+	if t.incrn == 999 && t.incr > time.Nanosecond {
+		t.rollover = t.incr * t.incrn
+		t.incrn = 1
+		t.incr = t.incr / 1000
+		if t.incr < time.Nanosecond {
+			t.incr = time.Nanosecond
+		}
+	}
+	return ts.Add(t.incr*t.incrn + t.rollover)
+}
--- a/plugins/parsers/grok/parser_test.go
+++ b/plugins/parsers/grok/parser_test.go
@@ -0,0 +1,961 @@
+package grok
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGrokParse(t *testing.T) {
+	parser := Parser{
+		Measurement: "t_met",
+		Patterns:    []string{"%{COMMON_LOG_FORMAT}"},
+	}
+	parser.Compile()
+	_, err := parser.Parse([]byte(`127.0.0.1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326`))
+	assert.NoError(t, err)
+}
+
+// Verify that patterns with a regex lookahead fail at compile time.
+func TestParsePatternsWithLookahead(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{MYLOG}"},
+		CustomPatterns: `
+			NOBOT ((?!bot|crawl).)*
+			MYLOG %{NUMBER:num:int} %{NOBOT:client}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	_, err := p.ParseLine(`1466004605359052000 bot`)
+	assert.Error(t, err)
+}
+
+func TestMeasurementName(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{COMMON_LOG_FORMAT}"},
+	}
+	assert.NoError(t, p.Compile())
+
+	// Parse an influxdb POST request
+	m, err := p.ParseLine(`127.0.0.1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":   int64(2326),
+			"auth":         "frank",
+			"client_ip":    "127.0.0.1",
+			"http_version": float64(1.0),
+			"ident":        "user-identifier",
+			"request":      "/apache_pb.gif",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+}
+
+func TestCLF_IPv6(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{COMMON_LOG_FORMAT}"},
+	}
+	assert.NoError(t, p.Compile())
+
+	m, err := p.ParseLine(`2001:0db8:85a3:0000:0000:8a2e:0370:7334 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":   int64(2326),
+			"auth":         "frank",
+			"client_ip":    "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
+			"http_version": float64(1.0),
+			"ident":        "user-identifier",
+			"request":      "/apache_pb.gif",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+
+	m, err = p.ParseLine(`::1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":   int64(2326),
+			"auth":         "frank",
+			"client_ip":    "::1",
+			"http_version": float64(1.0),
+			"ident":        "user-identifier",
+			"request":      "/apache_pb.gif",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+}
+
+func TestCustomInfluxdbHttpd(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{`\[httpd\] %{COMBINED_LOG_FORMAT} %{UUID:uuid:drop} %{NUMBER:response_time_us:int}`},
+	}
+	assert.NoError(t, p.Compile())
+
+	// Parse an influxdb POST request
+	m, err := p.ParseLine(`[httpd] ::1 - - [14/Jun/2016:11:33:29 +0100] "POST /write?consistency=any&db=telegraf&precision=ns&rp= HTTP/1.1" 204 0 "-" "InfluxDBClient" 6f61bc44-321b-11e6-8050-000000000000 2513`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":       int64(0),
+			"auth":             "-",
+			"client_ip":        "::1",
+			"http_version":     float64(1.1),
+			"ident":            "-",
+			"referrer":         "-",
+			"request":          "/write?consistency=any&db=telegraf&precision=ns&rp=",
+			"response_time_us": int64(2513),
+			"agent":            "InfluxDBClient",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "POST", "resp_code": "204"}, m.Tags())
+
+	// Parse an influxdb GET request
+	m, err = p.ParseLine(`[httpd] ::1 - - [14/Jun/2016:12:10:02 +0100] "GET /query?db=telegraf&q=SELECT+bytes%2Cresponse_time_us+FROM+logparser_grok+WHERE+http_method+%3D+%27GET%27+AND+response_time_us+%3E+0+AND+time+%3E+now%28%29+-+1h HTTP/1.1" 200 578 "http://localhost:8083/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.84 Safari/537.36" 8a3806f1-3220-11e6-8006-000000000000 988`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":       int64(578),
+			"auth":             "-",
+			"client_ip":        "::1",
+			"http_version":     float64(1.1),
+			"ident":            "-",
+			"referrer":         "http://localhost:8083/",
+			"request":          "/query?db=telegraf&q=SELECT+bytes%2Cresponse_time_us+FROM+logparser_grok+WHERE+http_method+%3D+%27GET%27+AND+response_time_us+%3E+0+AND+time+%3E+now%28%29+-+1h",
+			"response_time_us": int64(988),
+			"agent":            "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.84 Safari/537.36",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+}
+
+// common log format
+// 127.0.0.1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326
+func TestBuiltinCommonLogFormat(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{COMMON_LOG_FORMAT}"},
+	}
+	assert.NoError(t, p.Compile())
+
+	// Parse an influxdb POST request
+	m, err := p.ParseLine(`127.0.0.1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":   int64(2326),
+			"auth":         "frank",
+			"client_ip":    "127.0.0.1",
+			"http_version": float64(1.0),
+			"ident":        "user-identifier",
+			"request":      "/apache_pb.gif",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+}
+
+// common log format
+// 127.0.0.1 user1234 frank1234 [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326
+func TestBuiltinCommonLogFormatWithNumbers(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{COMMON_LOG_FORMAT}"},
+	}
+	assert.NoError(t, p.Compile())
+
+	// Parse an influxdb POST request
+	m, err := p.ParseLine(`127.0.0.1 user1234 frank1234 [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":   int64(2326),
+			"auth":         "frank1234",
+			"client_ip":    "127.0.0.1",
+			"http_version": float64(1.0),
+			"ident":        "user1234",
+			"request":      "/apache_pb.gif",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+}
+
+// combined log format
+// 127.0.0.1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326 "-" "Mozilla"
+func TestBuiltinCombinedLogFormat(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{COMBINED_LOG_FORMAT}"},
+	}
+	assert.NoError(t, p.Compile())
+
+	// Parse an influxdb POST request
+	m, err := p.ParseLine(`127.0.0.1 user-identifier frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326 "-" "Mozilla"`)
+	require.NotNil(t, m)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"resp_bytes":   int64(2326),
+			"auth":         "frank",
+			"client_ip":    "127.0.0.1",
+			"http_version": float64(1.0),
+			"ident":        "user-identifier",
+			"request":      "/apache_pb.gif",
+			"referrer":     "-",
+			"agent":        "Mozilla",
+		},
+		m.Fields())
+	assert.Equal(t, map[string]string{"verb": "GET", "resp_code": "200"}, m.Tags())
+}
+
+func TestCompileStringAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_A}"},
+		CustomPatterns: `
+			DURATION %{NUMBER}[nuµm]?s
+			RESPONSE_CODE %{NUMBER:response_code:tag}
+			RESPONSE_TIME %{DURATION:response_time:duration}
+			TEST_LOG_A %{NUMBER:myfloat:float} %{RESPONSE_CODE} %{IPORHOST:clientip} %{RESPONSE_TIME}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1.25 200 192.168.1.1 5.432µs`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+}
+
+func TestCompileErrorsOnInvalidPattern(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatterns: `
+			DURATION %{NUMBER}[nuµm]?s
+			RESPONSE_CODE %{NUMBER:response_code:tag}
+			RESPONSE_TIME %{DURATION:response_time:duration}
+			TEST_LOG_A %{NUMBER:myfloat:float} %{RESPONSE_CODE} %{IPORHOST:clientip} %{RESPONSE_TIME}
+		`,
+	}
+	assert.Error(t, p.Compile())
+
+	metricA, _ := p.ParseLine(`1.25 200 192.168.1.1 5.432µs`)
+	require.Nil(t, metricA)
+}
+
+func TestParsePatternsWithoutCustom(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{POSINT:ts:ts-epochnano} response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}"},
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1466004605359052000 response_time=20821 mymetric=10890.645`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"response_time": int64(20821),
+			"metric":        float64(10890.645),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+	assert.Equal(t, time.Unix(0, 1466004605359052000), metricA.Time())
+}
+
+func TestParseEpochNano(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{MYAPP}"},
+		CustomPatterns: `
+			MYAPP %{POSINT:ts:ts-epochnano} response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1466004605359052000 response_time=20821 mymetric=10890.645`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"response_time": int64(20821),
+			"metric":        float64(10890.645),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+	assert.Equal(t, time.Unix(0, 1466004605359052000), metricA.Time())
+}
+
+func TestParseEpoch(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{MYAPP}"},
+		CustomPatterns: `
+			MYAPP %{POSINT:ts:ts-epoch} response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1466004605 response_time=20821 mymetric=10890.645`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"response_time": int64(20821),
+			"metric":        float64(10890.645),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+	assert.Equal(t, time.Unix(1466004605, 0), metricA.Time())
+}
+
+func TestParseEpochDecimal(t *testing.T) {
+	var tests = []struct {
+		name    string
+		line    string
+		noMatch bool
+		err     error
+		tags    map[string]string
+		fields  map[string]interface{}
+		time    time.Time
+	}{
+		{
+			name: "ns precision",
+			line: "1466004605.359052000 value=42",
+			tags: map[string]string{},
+			fields: map[string]interface{}{
+				"value": int64(42),
+			},
+			time: time.Unix(0, 1466004605359052000),
+		},
+		{
+			name: "ms precision",
+			line: "1466004605.359 value=42",
+			tags: map[string]string{},
+			fields: map[string]interface{}{
+				"value": int64(42),
+			},
+			time: time.Unix(0, 1466004605359000000),
+		},
+		{
+			name: "second precision",
+			line: "1466004605 value=42",
+			tags: map[string]string{},
+			fields: map[string]interface{}{
+				"value": int64(42),
+			},
+			time: time.Unix(0, 1466004605000000000),
+		},
+		{
+			name: "sub ns precision",
+			line: "1466004605.123456789123 value=42",
+			tags: map[string]string{},
+			fields: map[string]interface{}{
+				"value": int64(42),
+			},
+			time: time.Unix(0, 1466004605123456789),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			parser := &Parser{
+				Patterns: []string{"%{NUMBER:ts:ts-epoch} value=%{NUMBER:value:int}"},
+			}
+			assert.NoError(t, parser.Compile())
+			m, err := parser.ParseLine(tt.line)
+
+			if tt.noMatch {
+				require.Nil(t, m)
+				require.Nil(t, err)
+				return
+			}
+
+			require.Equal(t, tt.err, err)
+
+			require.NotNil(t, m)
+			require.Equal(t, tt.tags, m.Tags())
+			require.Equal(t, tt.fields, m.Fields())
+			require.Equal(t, tt.time, m.Time())
+		})
+	}
+}
+
+func TestParseEpochErrors(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{MYAPP}"},
+		CustomPatterns: `
+			MYAPP %{WORD:ts:ts-epoch} response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	_, err := p.ParseLine(`foobar response_time=20821 mymetric=10890.645`)
+	assert.NoError(t, err)
+
+	p = &Parser{
+		Patterns: []string{"%{MYAPP}"},
+		CustomPatterns: `
+			MYAPP %{WORD:ts:ts-epochnano} response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	_, err = p.ParseLine(`foobar response_time=20821 mymetric=10890.645`)
+	assert.NoError(t, err)
+}
+
+func TestParseGenericTimestamp(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{`\[%{HTTPDATE:ts:ts}\] response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}`},
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[09/Jun/2016:03:37:03 +0000] response_time=20821 mymetric=10890.645`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"response_time": int64(20821),
+			"metric":        float64(10890.645),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+	assert.Equal(t, time.Unix(1465443423, 0).UTC(), metricA.Time().UTC())
+
+	metricB, err := p.ParseLine(`[09/Jun/2016:03:37:04 +0000] response_time=20821 mymetric=10890.645`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"response_time": int64(20821),
+			"metric":        float64(10890.645),
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t, time.Unix(1465443424, 0).UTC(), metricB.Time().UTC())
+}
+
+func TestParseGenericTimestampNotFound(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{`\[%{NOTSPACE:ts:ts}\] response_time=%{POSINT:response_time:int} mymetric=%{NUMBER:metric:float}`},
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[foobar] response_time=20821 mymetric=10890.645`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"response_time": int64(20821),
+			"metric":        float64(10890.645),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+}
+
+func TestCompileFileAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+			"myint":         int64(101),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+	assert.Equal(t,
+		time.Date(2016, time.June, 4, 12, 41, 45, 0, time.FixedZone("foo", 60*60)).Nanosecond(),
+		metricA.Time().Nanosecond())
+
+	metricB, err := p.ParseLine(`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"myfloat":    1.25,
+			"mystring":   "mystring",
+			"nomodifier": "nomodifier",
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t,
+		time.Date(2016, time.June, 4, 12, 41, 45, 0, time.FixedZone("foo", 60*60)).Nanosecond(),
+		metricB.Time().Nanosecond())
+}
+
+func TestCompileNoModifiersAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_C}"},
+		CustomPatterns: `
+			DURATION %{NUMBER}[nuµm]?s
+			TEST_LOG_C %{NUMBER:myfloat} %{NUMBER} %{IPORHOST:clientip} %{DURATION:rt}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1.25 200 192.168.1.1 5.432µs`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip": "192.168.1.1",
+			"myfloat":  "1.25",
+			"rt":       "5.432µs",
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+}
+
+func TestCompileNoNamesAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_C}"},
+		CustomPatterns: `
+			DURATION %{NUMBER}[nuµm]?s
+			TEST_LOG_C %{NUMBER} %{NUMBER} %{IPORHOST} %{DURATION}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1.25 200 192.168.1.1 5.432µs`)
+	require.Nil(t, metricA)
+	assert.NoError(t, err)
+}
+
+func TestParseNoMatch(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] notnumber 200 192.168.1.1 5.432µs 101`)
+	assert.NoError(t, err)
+	assert.Nil(t, metricA)
+}
+
+func TestCompileErrors(t *testing.T) {
+	// Compile fails because there are multiple timestamps:
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatterns: `
+			TEST_LOG_A %{HTTPDATE:ts1:ts-httpd} %{HTTPDATE:ts2:ts-httpd} %{NUMBER:mynum:int}
+		`,
+	}
+	assert.Error(t, p.Compile())
+
+	// Compile fails because file doesn't exist:
+	p = &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"/tmp/foo/bar/baz"},
+	}
+	assert.Error(t, p.Compile())
+}
+
+func TestParseErrors(t *testing.T) {
+	// Parse fails because the pattern doesn't exist
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_B}"},
+		CustomPatterns: `
+			TEST_LOG_A %{HTTPDATE:ts:ts-httpd} %{WORD:myword:int} %{}
+		`,
+	}
+	assert.Error(t, p.Compile())
+	_, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] notnumber 200 192.168.1.1 5.432µs 101`)
+	assert.Error(t, err)
+
+	// Parse fails because myword is not an int
+	p = &Parser{
+		Patterns: []string{"%{TEST_LOG_A}"},
+		CustomPatterns: `
+			TEST_LOG_A %{HTTPDATE:ts:ts-httpd} %{WORD:myword:int}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+	_, err = p.ParseLine(`04/Jun/2016:12:41:45 +0100 notnumber`)
+	assert.Error(t, err)
+
+	// Parse fails because myword is not a float
+	p = &Parser{
+		Patterns: []string{"%{TEST_LOG_A}"},
+		CustomPatterns: `
+			TEST_LOG_A %{HTTPDATE:ts:ts-httpd} %{WORD:myword:float}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+	_, err = p.ParseLine(`04/Jun/2016:12:41:45 +0100 notnumber`)
+	assert.Error(t, err)
+
+	// Parse fails because myword is not a duration
+	p = &Parser{
+		Patterns: []string{"%{TEST_LOG_A}"},
+		CustomPatterns: `
+			TEST_LOG_A %{HTTPDATE:ts:ts-httpd} %{WORD:myword:duration}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+	_, err = p.ParseLine(`04/Jun/2016:12:41:45 +0100 notnumber`)
+	assert.Error(t, err)
+
+	// Parse fails because the time layout is wrong.
+	p = &Parser{
+		Patterns: []string{"%{TEST_LOG_A}"},
+		CustomPatterns: `
+			TEST_LOG_A %{HTTPDATE:ts:ts-unix} %{WORD:myword:duration}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+	_, err = p.ParseLine(`04/Jun/2016:12:41:45 +0100 notnumber`)
+	assert.Error(t, err)
+}
+
+func TestTsModder(t *testing.T) {
+	tsm := &tsModder{}
+
+	reftime := time.Date(2006, time.December, 1, 1, 1, 1, int(time.Millisecond), time.UTC)
+	modt := tsm.tsMod(reftime)
+	assert.Equal(t, reftime, modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Microsecond*1), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Microsecond*2), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Microsecond*3), modt)
+
+	reftime = time.Date(2006, time.December, 1, 1, 1, 1, int(time.Microsecond), time.UTC)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime, modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Nanosecond*1), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Nanosecond*2), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Nanosecond*3), modt)
+
+	reftime = time.Date(2006, time.December, 1, 1, 1, 1, int(time.Microsecond)*999, time.UTC)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime, modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Nanosecond*1), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Nanosecond*2), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Nanosecond*3), modt)
+
+	reftime = time.Date(2006, time.December, 1, 1, 1, 1, 0, time.UTC)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime, modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Millisecond*1), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Millisecond*2), modt)
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime.Add(time.Millisecond*3), modt)
+
+	reftime = time.Time{}
+	modt = tsm.tsMod(reftime)
+	assert.Equal(t, reftime, modt)
+}
+
+func TestTsModder_Rollover(t *testing.T) {
+	tsm := &tsModder{}
+
+	reftime := time.Date(2006, time.December, 1, 1, 1, 1, int(time.Millisecond), time.UTC)
+	modt := tsm.tsMod(reftime)
+	for i := 1; i < 1000; i++ {
+		modt = tsm.tsMod(reftime)
+	}
+	assert.Equal(t, reftime.Add(time.Microsecond*999+time.Nanosecond), modt)
+
+	reftime = time.Date(2006, time.December, 1, 1, 1, 1, int(time.Microsecond), time.UTC)
+	modt = tsm.tsMod(reftime)
+	for i := 1; i < 1001; i++ {
+		modt = tsm.tsMod(reftime)
+	}
+	assert.Equal(t, reftime.Add(time.Nanosecond*1000), modt)
+}
+
+func TestShortPatternRegression(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{TS_UNIX:timestamp:ts-unix} %{NUMBER:value:int}"},
+		CustomPatterns: `
+		  TS_UNIX %{DAY} %{MONTH} %{MONTHDAY} %{HOUR}:%{MINUTE}:%{SECOND} %{TZ} %{YEAR}
+		`,
+	}
+	require.NoError(t, p.Compile())
+
+	metric, err := p.ParseLine(`Wed Apr 12 13:10:34 PST 2017 42`)
+	require.NoError(t, err)
+	require.NotNil(t, metric)
+
+	require.Equal(t,
+		map[string]interface{}{
+			"value": int64(42),
+		},
+		metric.Fields())
+}
+
+func TestTimezoneEmptyCompileFileAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+		Timezone:           "",
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+			"myint":         int64(101),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+	assert.Equal(t, int64(1465040505000000000), metricA.Time().UnixNano())
+
+	metricB, err := p.ParseLine(`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"myfloat":    1.25,
+			"mystring":   "mystring",
+			"nomodifier": "nomodifier",
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t, int64(1465044105000000000), metricB.Time().UnixNano())
+}
+
+func TestTimezoneMalformedCompileFileAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+		Timezone:           "Something/Weird",
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+			"myint":         int64(101),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+	assert.Equal(t, int64(1465040505000000000), metricA.Time().UnixNano())
+
+	metricB, err := p.ParseLine(`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"myfloat":    1.25,
+			"mystring":   "mystring",
+			"nomodifier": "nomodifier",
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t, int64(1465044105000000000), metricB.Time().UnixNano())
+}
+
+func TestTimezoneEuropeCompileFileAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+		Timezone:           "Europe/Berlin",
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+			"myint":         int64(101),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+	assert.Equal(t, int64(1465040505000000000), metricA.Time().UnixNano())
+
+	metricB, err := p.ParseLine(`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"myfloat":    1.25,
+			"mystring":   "mystring",
+			"nomodifier": "nomodifier",
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t, int64(1465036905000000000), metricB.Time().UnixNano())
+}
+
+func TestTimezoneAmericasCompileFileAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+		Timezone:           "Canada/Eastern",
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+			"myint":         int64(101),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+	assert.Equal(t, int64(1465040505000000000), metricA.Time().UnixNano())
+
+	metricB, err := p.ParseLine(`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"myfloat":    1.25,
+			"mystring":   "mystring",
+			"nomodifier": "nomodifier",
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t, int64(1465058505000000000), metricB.Time().UnixNano())
+}
+
+func TestTimezoneLocalCompileFileAndParse(t *testing.T) {
+	p := &Parser{
+		Patterns:           []string{"%{TEST_LOG_A}", "%{TEST_LOG_B}"},
+		CustomPatternFiles: []string{"./testdata/test-patterns"},
+		Timezone:           "Local",
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"myfloat":       float64(1.25),
+			"response_time": int64(5432),
+			"myint":         int64(101),
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{"response_code": "200"}, metricA.Tags())
+	assert.Equal(t, int64(1465040505000000000), metricA.Time().UnixNano())
+
+	metricB, err := p.ParseLine(`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`)
+	require.NotNil(t, metricB)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"myfloat":    1.25,
+			"mystring":   "mystring",
+			"nomodifier": "nomodifier",
+		},
+		metricB.Fields())
+	assert.Equal(t, map[string]string{}, metricB.Tags())
+	assert.Equal(t, time.Date(2016, time.June, 4, 12, 41, 45, 0, time.Local).UnixNano(), metricB.Time().UnixNano())
+}
+
+func TestNewlineInPatterns(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{`
+			%{SYSLOGTIMESTAMP:timestamp}
+		`},
+	}
+	require.NoError(t, p.Compile())
+	m, err := p.ParseLine("Apr 10 05:11:57")
+	require.NoError(t, err)
+	require.NotNil(t, m)
+}
+
+func TestSyslogTimestamp(t *testing.T) {
+	tests := []struct {
+		name     string
+		line     string
+		expected time.Time
+	}{
+		{
+			name:     "two digit day of month",
+			line:     "Sep 25 09:01:55 value=42",
+			expected: time.Date(2018, time.September, 25, 9, 1, 55, 0, time.UTC),
+		},
+		{
+			name:     "one digit day of month single space",
+			line:     "Sep 2 09:01:55 value=42",
+			expected: time.Date(2018, time.September, 2, 9, 1, 55, 0, time.UTC),
+		},
+		{
+			name:     "one digit day of month double space",
+			line:     "Sep  2 09:01:55 value=42",
+			expected: time.Date(2018, time.September, 2, 9, 1, 55, 0, time.UTC),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			p := &Parser{
+				Patterns: []string{`%{SYSLOGTIMESTAMP:timestamp:ts-syslog} value=%{NUMBER:value:int}`},
+				timeFunc: func() time.Time { return time.Date(2017, time.April, 1, 0, 0, 0, 0, time.UTC) },
+			}
+			require.NoError(t, p.Compile())
+			m, err := p.ParseLine(tt.line)
+			require.NoError(t, err)
+			require.NotNil(t, m)
+			require.Equal(t, tt.expected, m.Time())
+		})
+	}
+}
+
+func TestReplaceTimestampComma(t *testing.T) {
+
+	p := &Parser{
+		Patterns: []string{`%{TIMESTAMP_ISO8601:timestamp:ts-"2006-01-02 15:04:05.000"} successfulMatches=%{NUMBER:value:int}`},
+	}
+
+	require.NoError(t, p.Compile())
+	m, err := p.ParseLine("2018-02-21 13:10:34,555 successfulMatches=1")
+	require.NoError(t, err)
+	require.NotNil(t, m)
+
+	require.Equal(t, 2018, m.Time().Year())
+	require.Equal(t, 13, m.Time().Hour())
+	require.Equal(t, 34, m.Time().Second())
+	//Convert Nanosecond to milisecond for compare
+	require.Equal(t, 555, m.Time().Nanosecond()/1000000)
+}
--- a/plugins/parsers/grok/testdata/.DS_Store
+++ b/plugins/parsers/grok/testdata/.DS_Store
--- a/plugins/parsers/grok/testdata/test-patterns
+++ b/plugins/parsers/grok/testdata/test-patterns
@@ -0,0 +1,14 @@
+# Test A log line:
+#   [04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101
+DURATION %{NUMBER}[nuµm]?s
+RESPONSE_CODE %{NUMBER:response_code:tag}
+RESPONSE_TIME %{DURATION:response_time:duration}
+TEST_LOG_A \[%{HTTPDATE:timestamp:ts-httpd}\] %{NUMBER:myfloat:float} %{RESPONSE_CODE} %{IPORHOST:clientip} %{RESPONSE_TIME} %{NUMBER:myint:int}
+
+# Test B log line:
+#   [04/06/2016--12:41:45] 1.25 mystring dropme nomodifier
+TEST_TIMESTAMP %{MONTHDAY}/%{MONTHNUM}/%{YEAR}--%{TIME}
+TEST_LOG_B \[%{TEST_TIMESTAMP:timestamp:ts-"02/01/2006--15:04:05"}\] %{NUMBER:myfloat:float} %{WORD:mystring:string} %{WORD:dropme:drop} %{WORD:nomodifier}
+
+TEST_TIMESTAMP %{MONTHDAY}/%{MONTHNUM}/%{YEAR}--%{TIME}
+TEST_LOG_BAD \[%{TEST_TIMESTAMP:timestamp:ts-"02/01/2006--15:04:05"}\] %{NUMBER:myfloat:float} %{WORD:mystring:int} %{WORD:dropme:drop} %{WORD:nomodifier}
--- a/plugins/parsers/grok/testdata/test_a.log
+++ b/plugins/parsers/grok/testdata/test_a.log
@@ -0,0 +1 @@
+[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101
--- a/plugins/parsers/grok/testdata/test_b.log
+++ b/plugins/parsers/grok/testdata/test_b.log
@@ -0,0 +1 @@
+[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier
				`@@ -0,0 +1 @@`
				`[04/Jun/2016:12:41:45 +0100] 1.25 200 192.168.1.1 5.432µs 101`
				`@@ -0,0 +1 @@`
				`[04/06/2016--12:41:45] 1.25 mystring dropme nomodifier`