Use Lager to log RabbitMQ messages

By default, RabbitMQ now logs messages to a single file
($RABBITMQ_LOGS). The $RABBITMQ_SASL_LOGS variable is unused. To
configure how and which messages are logged, it's recommended to do it
from rabbitmq.config, not from the environment variable.

The old `log_levels` parameter is unsupported and categories are
replaced by Lager extra sinks. If you had in your rabbitmq.config:
    {rabbit, [
        {log_levels, [{connection, info}]}
      ]}
You can now configure Lager like this:
    {lager, [
        {extra_sinks, [
            {rabbit_connection_lager_event, [
                {handlers, [{lager_forwarder_backend, [lager_event, info]}]}
              ]}
          ]}
      ]}

rabbitmq-build.mk from rabbitmq-common is included in the top-level
Makefile. It sets the appropriate compiler options to enable Lager's
lager_transform parse_transform module.

rabbit_log calls are now converted by this parse_transform to direct
calls to lager:log(). To keep backward compatibility with other plugins,
the rabbit_log module still implements all the <level>() functions.
Compared to the parse_transformed calls, the main difference is the
logged message does not carry the file:line metadata.

Fixes #94.

1 files changed, 1 insertions, 0 deletions

diff --git a/include/rabbit_log.hrl b/include/rabbit_log.hrl
new file mode 100644
index 0000000000..fcb72e2e31
--- /dev/null
+++ b/include/rabbit_log.hrl
@@ -0,0 +1 @@
+-define(LAGER_SINK, rabbit_log_lager_event).