class Logging::Layouts::Parseable
This layout will produce parseable log output in either JSON or YAML format. This makes it much easier for machines to parse log files and perform analysis on those logs.
The information about the log event can be configured when the layout is created. Any or all of the following labels can be set as the items to log:
'logger' Used to output the name of the logger that generated the log event. 'timestamp' Used to output the timestamp of the log event. 'level' Used to output the level of the log event. 'message' Used to output the application supplied message associated with the log event. 'file' Used to output the file name where the logging request was issued. 'line' Used to output the line number where the logging request was issued. 'method' Used to output the method name where the logging request was issued. 'hostname' Used to output the hostname 'pid' Used to output the process ID of the currently running program. 'millis' Used to output the number of milliseconds elapsed from the construction of the Layout until creation of the log event. 'thread_id' Used to output the object ID of the thread that generated the log event. 'thread' Used to output the name of the thread that generated the log event. Name can be specified using Thread.current[:name] notation. Output empty string if name not specified. This option helps to create more human readable output for multithread application logs.
These items are supplied to the layout as an array of strings. The items 'file', 'line', and 'method' will only work if the Logger generating the events is configured to generate tracing information. If this is not the case these fields will always be empty.
When configured to output log events in YAML format, each log message will be formatted as a hash in it's own YAML document. The hash keys are the name of the item, and the value is what you would expect it to be. Therefore, for the default set of times log message would appear as follows:
--- timestamp: 2009-04-17T16:15:42 level: INFO logger: Foo::Bar message: this is a log message --- timestamp: 2009-04-17T16:15:43 level: ERROR logger: Foo message: <RuntimeError> Oooops!!
The output order of the fields is not guaranteed to be the same as the order specified in the items list. This is because Ruby hashes are not ordered by default (unless you're running this in Ruby 1.9).
When configured to output log events in JSON format, each log message will be formatted as an object (in the JSON sense of the word) on it's own line in the log output. Therefore, to parse the output you must read it line by line and parse the individual objects. Taking the same example above the JSON output would be:
{"timestamp":"2009-04-17T16:15:42","level":"INFO","logger":"Foo::Bar","message":"this is a log message"} {"timestamp":"2009-04-17T16:15:43","level":"ERROR","logger":"Foo","message":"<RuntimeError> Oooops!!"}
The output order of the fields is guaranteed to be the same as the order specified in the items list.
Attributes
Public Class Methods
Create a new Parseable layout that outputs log events using JSON style formatting. See the initializer documentation for available options.
# File lib/logging/layouts/parseable.rb, line 159 def self.json( opts = {} ) opts[:style] = 'json' new(opts) end
Creates a new Parseable layout using the following options:
:style => :json or :yaml :items => %w[timestamp level logger message] :utc_offset => "-06:00" or -21600 or "UTC"
# File lib/logging/layouts/parseable.rb, line 184 def initialize( opts = {} ) super @created_at = Time.now @style = opts.fetch(:style, 'json').to_s.intern self.items = opts.fetch(:items, %w[timestamp level logger message]) end
Create a new Parseable layout that outputs log events using YAML style formatting. See the initializer documentation for available options.
# File lib/logging/layouts/parseable.rb, line 170 def self.yaml( opts = {} ) opts[:style] = 'yaml' new(opts) end
Public Instance Methods
Internal: Format any nested exceptions found in the given exception `e` while respecting the maximum `cause_depth`.
e - Exception to format
Returns the cause formatted as a Hash
# File lib/logging/layouts/parseable.rb, line 244 def format_cause(e) rv = curr = {} prev = nil cause_depth.times do break unless e.respond_to?(:cause) && e.cause cause = e.cause curr[:class] = cause.class.name curr[:message] = cause.message curr[:backtrace] = format_cause_backtrace(e, cause) if backtrace? && cause.backtrace prev[:cause] = curr unless prev.nil? prev, curr = curr, {} e = cause end if e.respond_to?(:cause) && e.cause prev[:cause] = {message: "Further #cause backtraces were omitted"} end rv end
Public: Take a given object and convert it into a format suitable for inclusion as a log message. The conversion allows the object to be more easily expressed in YAML or JSON form.
If the object is an Exception, then this method will return a Hash containing the exception class name, message, and backtrace (if any).
obj - The Object to format
Returns the formatted Object.
# File lib/logging/layouts/parseable.rb, line 219 def format_obj( obj ) case obj when Exception hash = { :class => obj.class.name, :message => obj.message } hash[:backtrace] = obj.backtrace if backtrace? && obj.backtrace cause = format_cause(obj) hash[:cause] = cause unless cause.empty? hash when Time iso8601_format(obj) else obj end end
Set the log event items that will be formatted by this layout. These items, and only these items, will appear in the log output.
# File lib/logging/layouts/parseable.rb, line 199 def items=( ary ) @items = Array(ary).map {|name| name.to_s.downcase} valid = DIRECTIVE_TABLE.keys @items.each do |name| raise ArgumentError, "unknown item - #{name.inspect}" unless valid.include? name end create_format_method end
Private Instance Methods
Call the appropriate class level create format method based on the style of this parseable layout.
# File lib/logging/layouts/parseable.rb, line 274 def create_format_method case @style when :json; Parseable.create_json_format_method(self) when :yaml; Parseable.create_yaml_format_method(self) else raise ArgumentError, "unknown format style '#@style'" end end
Convert the given `time` into an ISO8601 formatted time string.
# File lib/logging/layouts/parseable.rb, line 283 def iso8601_format( time ) value = apply_utc_offset(time) str = value.strftime('%Y-%m-%dT%H:%M:%S') str << ('.%06d' % value.usec) offset = value.gmt_offset.abs return str << 'Z' if offset == 0 offset = sprintf('%02d:%02d', offset / 3600, offset % 3600 / 60) return str << (value.gmt_offset < 0 ? '-' : '+') << offset end