Lorekeeper
LoreKeeper contains a highly optimized JSON logger. It outputs messages as JSON and let the users to add their own customized fields. When used without extra fields it outputs 20% faster than the standard Logger for messages not longer than one line of text.
Installation
Add this line to your application's Gemfile:
gem 'lorekeeper', '~> 1.7'
And then execute:
bundle
Usage
Normal logging methods
LoreKeeper::JSONLogger API is compatible with the stdlib's Logger's.
logger.error("This is a message")
Will output:
{
"message": "This is a message",
"timestamp": "1970-01-01T00:00:00.000+0100",
"level": "debug"
}
Timestamps use ISO8601. Messages are JSON escaped so the total result is JSON parseable.
Log Levels
Method Name | JSON Property |
---|---|
debug | "level": "debug" |
info | "level": "info" |
warn | "level": "warning" |
error | "level": "error" |
fatal | "level": "fatal" |
Adding keys to the output
Keys can be added to the output at any moment.
These keys will be output in each message till they are removed again.
If you want to output keys in only one message use the *_with_data
method instead.
Keys can be added using the add_fields
method which accepts a hash:
logger.add_fields("role" => "backend")
logger.error("This is a message")
logger.warn("This is another message")
Will output:
{
"message": "This is a message",
"timestamp": "1970-01-01T00:00:00.000+0100",
"level": "error",
"role": "backend"
}
{
"message": "This is another message",
"timestamp": "1970-01-01T00:00:00.000+0100",
"level": "warning",
"role": "backend"
}
Because of speed purposes the JSON dumping is done as simply as possible. If you provide a hash of keys like:
{ key: 'value' }
The output will include:
{ ":key": "value" }
Logging methods with data
All methods (info, debug, etc.) have a *_with_data
equivalent: info_with_data
, debug_with_data
, etc.
These methods accept and extra hash to add it to the JSON.
logger.error_with_data('message', { data1: 'Extra data', data2: 'Extra data2' })
Will output:
{
"message": "This is a message",
"timestamp": "1970-01-01T00:00:00.000+0100",
"level": "debug",
"data": {
"data1": "Extra data",
"data2": "Extra data2"
}
}
Logging exceptions
There is a method to help you log exceptions in an standard way.
rescue => e
logger.exception(e)
end
Will output:
{
"message": "#{e.message}",
"timestamp": "1970-01-01T00:00:00.000+0100",
"level": "error",
"exception": "<exception name>",
"stack": [
"<stacktraceline1>",
"<stacktraceline2>"
]
}
This method also accepts a custom message, data and log level.
rescue => e
logger.exception(e, "custom msg!", { some: { data: 123 } }, :warn)
end
Will output:
{
"message": "custom msg!",
"timestamp": "1970-01-01T00:00:00.000+0100",
"level": "warning",
"data": {
":some": {
":data": 123
}
},
"exception": "<exception name>",
"stack": [
"<stacktraceline1>",
"<stacktraceline2>"
]
}
Alternatively you can use named parameters:
rescue => e
logger.exception(e, message: "custom msg!", data: { some: { data: 123 } }, level: :warn)
end
This is specially useful when there is no custom message or data:
rescue => e
logger.exception(e, level: :warn)
end
License
The gem is available as open source under the terms of the MIT License.