Add polling method to logparser and tail inputs (#3213)

plugins/inputs/logparser/README.md

@@ -15,12 +15,15 @@ regex patterns.
   ##   /var/log/*/*.log    -> find all .log files with a parent dir in /var/log
   ##   /var/log/apache.log -> only tail the apache log file
   files = ["/var/log/apache/access.log"]
-  
+
   ## Read files that currently exist from the beginning. Files that are created
   ## while telegraf is running (and that match the "files" globs) will always
   ## be read from the beginning.
   from_beginning = false
 
+  ## Method used to watch for file updates.  Can be either "inotify" or "poll".
+  # watch_method = "inotify"
+
   ## Parse logstash-style "grok" patterns:
   ##   Telegraf built-in parsing patterns: https://goo.gl/dkay10
   [inputs.logparser.grok]
@@ -34,15 +37,15 @@ regex patterns.
 
     ## Name of the outputted measurement name.
     measurement = "apache_access_log"
-    
+
     ## Full path(s) to custom pattern files.
     custom_pattern_files = []
-    
+
     ## Custom patterns can also be defined here. Put one pattern per line.
     custom_patterns = '''
     '''
 
-    ## Timezone allows you to provide an override for timestamps that 
+    ## Timezone allows you to provide an override for timestamps that
     ## don't already include an offset
     ## e.g. 04/06/2016 12:41:45 data one two 5.43µs
     ##
@@ -145,7 +148,7 @@ Wed Apr 12 13:10:34 PST 2017 value=42
 For cases where the timestamp itself is without offset, the `timezone` config var is available
 to denote an offset. By default (with `timezone` either omit, blank or set to `"UTC"`), the times
 are processed as if in the UTC timezone. If specified as `timezone = "Local"`, the timestamp
-will be processed based on the current machine timezone configuration. Lastly, if using a 
+will be processed based on the current machine timezone configuration. Lastly, if using a
 timezone from the list of Unix [timezones](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones), the logparser grok will attempt to offset
 the timestamp accordingly. See test cases for more detailed examples.
 

plugins/inputs/logparser/logparser.go

@@ -19,6 +19,10 @@ import (
 	"github.com/influxdata/telegraf/plugins/inputs/logparser/grok"
 )
 
+const (
+	defaultWatchMethod = "inotify"
+)
+
 // LogParser in the primary interface for the plugin
 type LogParser interface {
 	ParseLine(line string) (telegraf.Metric, error)
@@ -34,6 +38,7 @@ type logEntry struct {
 type LogParserPlugin struct {
 	Files         []string
 	FromBeginning bool
+	WatchMethod   string
 
 	tailers map[string]*tail.Tail
 	lines   chan logEntry
@@ -61,6 +66,9 @@ const sampleConfig = `
   ## be read from the beginning.
   from_beginning = false
 
+  ## Method used to watch for file updates.  Can be either "inotify" or "poll".
+  # watch_method = "inotify"
+
   ## Parse logstash-style "grok" patterns:
   ##   Telegraf built-in parsing patterns: https://goo.gl/dkay10
   [inputs.logparser.grok]
@@ -167,6 +175,11 @@ func (l *LogParserPlugin) tailNewfiles(fromBeginning bool) error {
 		seek.Offset = 0
 	}
 
+	var poll bool
+	if l.WatchMethod == "poll" {
+		poll = true
+	}
+
 	// Create a "tailer" for each file
 	for _, filepath := range l.Files {
 		g, err := globpath.Compile(filepath)
@@ -188,6 +201,7 @@ func (l *LogParserPlugin) tailNewfiles(fromBeginning bool) error {
 					Follow:    true,
 					Location:  &seek,
 					MustExist: true,
+					Poll:      poll,
 					Logger:    tail.DiscardingLogger,
 				})
 			if err != nil {
@@ -285,6 +299,8 @@ func (l *LogParserPlugin) Stop() {
 
 func init() {
 	inputs.Add("logparser", func() telegraf.Input {
-		return &LogParserPlugin{}
+		return &LogParserPlugin{
+			WatchMethod: defaultWatchMethod,
+		}
 	})
 }

plugins/inputs/tail/README.md

@@ -39,6 +39,9 @@ The plugin expects messages in one of the
   ## Whether file is a named pipe
   pipe = false
 
+  ## Method used to watch for file updates.  Can be either "inotify" or "poll".
+  # watch_method = "inotify"
+
   ## Data format to consume.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:

plugins/inputs/tail/tail.go

@@ -15,10 +15,15 @@ import (
 	"github.com/influxdata/telegraf/plugins/parsers"
 )
 
+const (
+	defaultWatchMethod = "inotify"
+)
+
 type Tail struct {
 	Files         []string
 	FromBeginning bool
 	Pipe          bool
+	WatchMethod   string
 
 	tailers []*tail.Tail
 	parser  parsers.Parser
@@ -50,6 +55,9 @@ const sampleConfig = `
   ## Whether file is a named pipe
   pipe = false
 
+  ## Method used to watch for file updates.  Can be either "inotify" or "poll".
+  # watch_method = "inotify"
+
   ## Data format to consume.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:
@@ -83,6 +91,11 @@ func (t *Tail) Start(acc telegraf.Accumulator) error {
 		}
 	}
 
+	var poll bool
+	if t.WatchMethod == "poll" {
+		poll = true
+	}
+
 	// Create a "tailer" for each file
 	for _, filepath := range t.Files {
 		g, err := globpath.Compile(filepath)
@@ -96,6 +109,7 @@ func (t *Tail) Start(acc telegraf.Accumulator) error {
 					Follow:    true,
 					Location:  seek,
 					MustExist: true,
+					Poll:      poll,
 					Pipe:      t.Pipe,
 					Logger:    tail.DiscardingLogger,
 				})