Class: LogStash::Inputs::File

Inherits:

Base

• Object
• Base
• LogStash::Inputs::File

Defined in:

lib/logstash/inputs/file.rb

Overview

Stream events from files, normally by tailing them in a manner similar to ‘tail -0F` but optionally reading them from the beginning.

By default, each event is assumed to be one line. If you would like to join multiple log lines into one event, you’ll want to use the multiline codec or filter.

The plugin aims to track changing files and emit new content as it’s appended to each file. It’s not well-suited for reading a file from beginning to end and storing all of it in a single event (not even with the multiline codec or filter).

Tracking of current position in watched files

The plugin keeps track of the current position in each file by recording it in a separate file named sincedb. This makes it possible to stop and restart Logstash and have it pick up where it left off without missing the lines that were added to the file while Logstash was stopped.

By default, the sincedb file is placed in the home directory of the user running Logstash with a filename based on the filename patterns being watched (i.e. the ‘path` option). Thus, changing the filename patterns will result in a new sincedb file being used and any existing current position state will be lost. If you change your patterns with any frequency it might make sense to explicitly choose a sincedb path with the `sincedb_path` option.

Sincedb files are text files with four columns:

. The inode number (or equivalent). . The major device number of the file system (or equivalent). . The minor device number of the file system (or equivalent). . The current byte offset within the file.

On non-Windows systems you can obtain the inode number of a file with e.g. ‘ls -li`.

File rotation

File rotation is detected and handled by this input, regardless of whether the file is rotated via a rename or a copy operation. To support programs that write to the rotated file for some time after the rotation has taken place, include both the original filename and the rotated filename (e.g. /var/log/syslog and /var/log/syslog.1) in the filename patterns to watch (the ‘path` option). Note that the rotated filename will be treated as a new file so if `start_position` is set to ’beginning’ the rotated file will be reprocessed.

With the default value of ‘start_position` (’end’) any messages written to the end of the file between the last read operation prior to the rotation and its reopening under the new name (an interval determined by the ‘stat_interval` and `discover_interval` options) will not get picked up.

Instance Method Summary

• #register ⇒ Object
• #run(queue) ⇒ Object
• #stop ⇒ Object

Instance Method Details

#register ⇒ Object

# File 'lib/logstash/inputs/file.rb', line 124

def register
  require "addressable/uri"
  require "filewatch/tail"
  require "digest/md5"
  @logger.info("Registering file input", :path => @path)
  @host = Socket.gethostname.force_encoding(Encoding::UTF_8)

  @tail_config = {
    :exclude => @exclude,
    :stat_interval => @stat_interval,
    :discover_interval => @discover_interval,
    :sincedb_write_interval => @sincedb_write_interval,
    :delimiter => @delimiter,
    :logger => @logger,
  }

  @path.each do |path|
    if Pathname.new(path).relative?
      raise ArgumentError.new("File paths must be absolute, relative path specified: #{path}")
    end
  end

  if @sincedb_path.nil?
    if ENV["SINCEDB_DIR"].nil? && ENV["HOME"].nil?
      @logger.error("No SINCEDB_DIR or HOME environment variable set, I don't know where " \
                    "to keep track of the files I'm watching. Either set " \
                    "HOME or SINCEDB_DIR in your environment, or set sincedb_path in " \
                    "in your Logstash config for the file input with " \
                    "path '#{@path.inspect}'")
      raise # TODO(sissel): HOW DO I FAIL PROPERLY YO
    end

    #pick SINCEDB_DIR if available, otherwise use HOME
    sincedb_dir = ENV["SINCEDB_DIR"] || ENV["HOME"]

    # Join by ',' to make it easy for folks to know their own sincedb
    # generated path (vs, say, inspecting the @path array)
    @sincedb_path = File.join(sincedb_dir, ".sincedb_" + Digest::MD5.hexdigest(@path.join(",")))

    # Migrate any old .sincedb to the new file (this is for version <=1.1.1 compatibility)
    old_sincedb = File.join(sincedb_dir, ".sincedb")
    if File.exists?(old_sincedb)
      @logger.info("Renaming old ~/.sincedb to new one", :old => old_sincedb,
                   :new => @sincedb_path)
      File.rename(old_sincedb, @sincedb_path)
    end

    @logger.info("No sincedb_path set, generating one based on the file path",
                 :sincedb_path => @sincedb_path, :path => @path)
  end

  if File.directory?(@sincedb_path)
    raise ArgumentError.new("The \"sincedb_path\" argument must point to a file, received a directory: \"#{@sincedb_path}\"")
  end

  @tail_config[:sincedb_path] = @sincedb_path

  if @start_position == "beginning"
    @tail_config[:start_new_files_at] = :beginning
  end
end

#run(queue) ⇒ Object

# File 'lib/logstash/inputs/file.rb', line 187

def run(queue)
  @tail = FileWatch::Tail.new(@tail_config)
  @tail.logger = @logger
  @path.each { |path| @tail.tail(path) }

  @tail.subscribe do |path, line|
    @logger.debug? && @logger.debug("Received line", :path => path, :text => line)
    @codec.decode(line) do |event|
      event["[@metadata][path]"] = path
      event["host"] = @host if !event.include?("host")
      event["path"] = path if !event.include?("path")
      decorate(event)
      queue << event
    end
  end
end

#stop ⇒ Object

# File 'lib/logstash/inputs/file.rb', line 205

def stop
  @tail.quit if @tail # _sincedb_write is called implicitly
end