Lager is a standard logging tool for Erlang, this project crates lager formatter to output messages in GELF format and lager backend to send messages via UDP to a graylog server.

• Support for compression gzip or zlib
• Support for chunk encoded GELF messages
• Works with lager 3.x

Include this backend into your project using rebar:

{graylog_lager, ".*", {git, "https://github.com/silviucpp/graylog_lager.git", "master"}}

Then you need to add a new handler in lager configuration, usually in your app.config file, for example:

{lager, [
    {handlers, [
        {graylog_lager_udp_backend, [
            {host, "127.0.0.1"},
            {port, 12201},
            {level, info},
            {format_config, [
                {compression, disabled},
                {extra_fields, [
                    {<<"_environment">>, <<"production">>}
                ]}
            ]}
        ]}
    ]}
]}

Backend configuration parameters:

• host: graylog server host, example: {host, "127.0.0.1"}
• port: graylog server port, example: {port, 12201}
• level: minimum logging level - messages below that level will be dropped. One of the above values (debug, info, notice, warning, error, critical, alert)
• format_config: backend-specific configuration - a proplist with:
  • compression: one of disabled, gzip, zlib (atom, defaults to disabled)
  • extra_fields: optional proplist of {name, value}, they will be sent as additional fields to graylog. The name must be a binary starting with an underscore, while the value must be any term.
  • hostname: optional binary with the hostname. If not provided will be automatically detected.
• formatter: In case you want to change the GELF formatter module. Default : {formatter, graylog_lager_gelf_formatter}
• chunk_size: The max size of each UPD packet: default 8154. Valid value between interval 1420 - 8154. Example: {chunk_size, 8154}
• inet_family: Specify the inet family. Default to inet. Supported values inet or inet6

Also support the following sink configs described in lager readme:

• high_water_mark
• flush_queue
• flush_threshold