jsonformat

A custom formatter for Erlang OTP logger that outputs JSON using jsx

Getting Started

This project should be added as a dependency to your project

Prerequisites

sys.config:

[ { kernel
  , [ { logger
      ,[ { handler
         , default
         , logger_std_h
         , #{formatter => {jsonformat, #{new_line => true}}}
         }
       ] }
    , {logger_level, info}
   ] }
].

shell:

> logger:info(#{a => b}).
{"a":"b","gl":"<0.178.0>","level":"info","pid":"<0.182.0>","report_cb":"fun logger:format_otp_report/1","time":1585902924341139}ok

Configuration Options

To print each json object to a new line, set new_line to true:

#{formatter => {jsonformat, #{ new_line => true }}}

To specify which kind of line ending to use, set new_line_type to one of nl, crlf, cr, unix, windows or macos9. These correspond to:

nl or unix means \n, ASCII character 0x0A
crlf or windows means \r\n, ASCII characters 0x0D 0x0A
cr or macos9 means \r, ASCII character 0x0D

The default line ending if none is specified is nl.

#{formatter => {jsonformat, #{ new_line => true, new_line_type => crlf }}}

To control what is being included in the log object from the metadata, there are two ways. One can opt-out from fields. Default opts out is [report_cb].

#{ meta_without => [report_cb, gl, file, domain] }

Or for very detailed control there is instead opt-in.

#{ meta_with => [time, mfa, line, user_key, client_key] }

To rename keys in the resulting json object, provide a key_mapping. For example, to rename the time and level keys to timestamp and lvl respectively, use:

#{formatter => {jsonformat, #{ key_mapping => #{ time => timestamp
                                               , level => lvl }}}}

To format values in the resulting json object, provide a map of format_funs. For example, to format the value associated with the time key, use:

#{formatter => {jsonformat, #{ format_funs => #{ time => fun(T) -> ... end }}}

Note that key_mappings are applied before format_funs.

Built in formatters

fun jsonformat:system_time_to_iso8601/1

Will take a logger:timestamp() and print it in the format of yyyy-mm-ddTHH:MM:SSZ

Running the tests

$ rebar3 eunit

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

Commit message convention

We use Conventional Commits.

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

License

This project is licensed under the MIT License - see the LICENSE file for details

kivra / jsonformat