Safe Haskell | Safe |
---|---|
Language | Haskell2010 |
This module exports tools for typing, parsing, and rendering logs in the df1 hierarchical structured logging format.
Consider this a preview release: The API is likely to stay stable, but extensive testing, formalization and tooling is due.
Draft BNF specification of the df1 log line format (TO BE VERIFIED):
<log> ::= <timestamp> " " <path> " " <level> " " <message> <path> ::= <path1> " " <path> | <path1> | "" <path1> ::= "/" <segment> | <key> "=" <value> <segment> ::= zero or more characters until " " <key> ::= zero or more characters until (" " | "=") <value> ::= zero or more characters until " " <message> ::= zero or more characters until LF ("\n") <level> ::= "DEBUG" | "INFO" | "NOTICE" | "WARNING" | "ERROR" | "CRITICAL" | "ALERT" | "EMERGENCY" <timestamp> ::= <year> "-" <month> "-" <day> "T" <hour> ":" <minute> ":" <second> "." <nanosecond> "Z" <year> ::= <digit> <digit> <digit> <digit> <month> ::= <digit> <digit> <day> ::= <digit> <digit> <hour> ::= <digit> <digit> <minute> ::= <digit> <digit> <second> ::= <digit> <digit> <nanosecond> ::= <digit> <digit> <digit> <digit> <digit> <digit> <digit> <digit> <digit> <digit> ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
Synopsis
- data Log = Log {
- log_time :: !SystemTime
- log_level :: !Level
- log_path :: !(Seq Path)
- log_message :: !Message
- data Level
- data Path
- data Segment
- unSegment :: Segment -> Text
- class ToSegment a where
- data Key
- unKey :: Key -> Text
- class ToKey a where
- data Value
- unValue :: Value -> Text
- class ToValue a where
- data Message
- unMessage :: Message -> Text
- class ToMessage a where
- parse :: Parser Log
- render :: Log -> Builder
- renderColor :: Log -> Builder
Types
Log | |
|
Importance of the logged message.
These levels, listed in increasing order of importance, correspond to the levels used by syslog(3).
Debug | Message intended to be useful only when deliberately debugging a program. |
Info | Informational message. |
Notice | A condition that is not an error, but should possibly be handled specially. |
Warning | A warning condition, such as an exception being gracefully handled or some missing configuration setting being assigned a default value. |
Error | Error condition, such as an unhandled exception. |
Critical | Critical condition that could result in system failure, such as a disk running out of space. |
Alert | A condition that should be corrected immediately, such as a corrupted database. |
Emergency | System is unusable. |
Path
represents the hierarchical structure of logged messages.
For example, consider a df1 log line as like the following:
1999-12-20T07:11:39.230553031Z /foo x=a y=b /bar /qux z=c z=d WARNING Something
For that line, the log_path
attribute of the Log
datatype will contain
the following:
[Push
(segment
"foo") ,Attr
(key
"x") (value
"a") ,Attr
(key
"y") (value
"b") ,Push
(segment
"bar") ,Push
(segment
"qux") ,Attr
(key
"z") (value
"c") ,Attr
(key
"z") (value
"d") ] ::Seq
Path
Please notice that [] ::
is a valid path insofar as df1
is concerned, and that Seq
Path
Attr
and Push
can be juxtapositioned in any order.
A path segment.
If you have the OverloadedStrings
GHC extension enabled, you can build a
Segment
using a string literal:
"foo" :: Segment
Otherwise, you can use fromString
or segment
.
Notice that "" ::
is acceptable, and will be correctly rendered
and parsed back.Segment
class ToSegment a where Source #
Convert an arbitrary type to a Segment
.
You are encouraged to create custom ToSegment
instances for your types
making sure you avoid rendering sensitive details such as passwords, so that
they don't accidentally end up in logs.
Any characters that need to be escaped for rendering will be automatically escaped at rendering time. You don't need to escape them here.
An attribute key (see Attr
).
If you have the OverloadedStrings
GHC extension enabled, you can build a
Key
using a string literal:
"foo" :: Key
Otherwise, you can use fromString
or key
.
Notice that "" ::
is acceptable, and will be correctly rendered and
parsed back.Key
Convert an arbitrary type to a Key
.
You are encouraged to create custom ToKey
instances for your types
making sure you avoid rendering sensitive details such as passwords, so that
they don't accidentally end up in logs.
Any characters that need to be escaped for rendering will be automatically escaped at rendering time. You don't need to escape them here.
An attribute value (see Attr
).
If you have the OverloadedStrings
GHC extension enabled, you can build a
Value
using a string literal:
"foo" :: Value
Otherwise, you can use fromString
or value
.
Notice that "" ::
is acceptable, and will be correctly rendered
and parsed back.Value
class ToValue a where Source #
Convert an arbitrary type to a Value
.
You are encouraged to create custom ToValue
instances for your types
making sure you avoid rendering sensitive details such as passwords, so that
they don't accidentally end up in logs.
Any characters that need to be escaped for rendering will be automatically escaped at rendering time. You don't need to escape them here.
Instances
ToValue Bool Source # | |
ToValue Double Source # | |
ToValue Float Source # | |
ToValue Int Source # | |
ToValue Int8 Source # | |
ToValue Int16 Source # | |
ToValue Int32 Source # | |
ToValue Int64 Source # | |
ToValue Integer Source # | |
ToValue Natural Source # | |
ToValue Word Source # | |
ToValue Word8 Source # | |
ToValue Word16 Source # | |
ToValue Word32 Source # | |
ToValue Word64 Source # | |
ToValue Text Source # | x :: |
ToValue Text Source # | x :: |
ToValue String Source # | x :: |
ToValue SomeException Source # | |
ToValue Value Source # | Identity. |
A message text.
If you have the OverloadedStrings
GHC extension enabled, you can build a
Message
using a string literal:
"foo" :: Message
Otherwise, you can use fromString
or message
.
Notice that "" ::
is acceptable, and will be correctly rendered
and parsed back.Message
class ToMessage a where Source #
Convert an arbitrary type to a Message
.
You are encouraged to create custom ToMessage
instances for your types
making sure you avoid rendering sensitive details such as passwords, so that
they don't accidentally end up in logs.
Any characters that need to be escaped for rendering will be automatically escaped at rendering time. You don't need to escape them here.
Parsing
If sucessful, parsing will stop after the first CR or LF newline marker if any, otherwise it will consume all input.
Rendering
renderColor :: Log -> Builder Source #