Disabling Rails default LogSubscribers

[Jeffrey Jones]

Hello all.

I find myself in unfamiliar territory by posting to this list but here
we go.

I am doing some experimentation regarding logging in JSON formats for
integration with systems like LogStash. So far things are reasonably
good but there is one thing in rails which is making things a lot harder
than they need to be.

At the moment rails has a large number of LogSubscribers such as
ActiveRecord::ExplainSubscriber and ActionController::LogSubscriber
which are automatically subscribed to the Notifications system.

What I would like to be able to do is stop this automatic subscribing
from happening (in effect turning off the rails default logging system).

Currently this is not possible as far as I can tell, it is possible to
go through all the various notifications and remove subscribers but this
is a pain, is not very granular and is generally a very hack'ish situation.

Now, messing around with the internals of rails is something I do not
have a huge amount of experience with so I would like to ask the core
members:

1. Before I start would there be any non-technical objections to a pull
request to allow for us to disable all the default LogSubscribers?
2. If not would anyone be willing to offer advice / guidance / checking
the design as I put this together?

cheers

Jeff

[Aaron Patterson]

I'd rather we don't have something specific to *log* subscribers.
You're right though, there is no way to find the *types* of listeners
listening on each channel.

Maybe just being able to access the list of subscribers would be enough?

> 2. If not would anyone be willing to offer advice / guidance /
> checking the design as I put this together?

Yes. Put together an example of an API you would like (you don't need
to actually make it work), and I'll help you figure something out.

The more you can share about the problem you're trying to solve, the
more we can help!

--
Aaron Patterson
http://tenderlovemaking.com/

[Jeffrey Jones]

I think there is the possibility for two things here. First is adding a
few functions to make it easier to see all / types of subscribers
to the notifications system which would be a good thing.

For my purposes though what I would really like to do is be able to stop
the default Rails subscribers from subscribing in the first place.
At the moment they all automatically subscribe as soon as they are
loaded (Subscribing is done automatically in the same file as they are
defined.).

>> 2. If not would anyone be willing to offer advice / guidance /
>> checking the design as I put this together?
> Yes. Put together an example of an API you would like (you don't need
> to actually make it work), and I'll help you figure something out.
>
> The more you can share about the problem you're trying to solve, the
> more we can help!
>

The problem I have is that I want to write JSON formatted log files that
contain the same information as you get from the basic rails ones (to
start with), something like the following:
https://gist.github.com/3694987 but it is not as easy as it should be to
silence the default rails logging system.

I could of course kludge things and just use separate logfile for the
JSON stuff and redirect the default loggers to /dev/null or something
but that feels wrong. I do actually have a plan for dealing with people
using the logger with plain strings but I would still like to get rid of
all the noise from the rails default subscribers.

I could also do something like this in a gem's railtie:
https://gist.github.com/3740558 but this is imprecise as you can get.

What I would love to be able to do is something along the lines of

config.default_subscibers.disable = true

in application.rb (or a railtie) to stop all of them from subscribing
themselves in the first place, it just seems like the cleaner approach.

Cheers

Jeff

[Brian Durand]

I've also just found a use case where I'd like to unsubscribe the default subscribers. I'd like to turn on INFO level logging for my application to get some better visibility into the running production application. However, the application gets a ton of traffic (100's of requests/second) and with the default subscribers the logs will fill up with gigabytes of data in a matter of minutes.

What I think would make sense is to remove the static subscribe code from the LogSubscriber classes and instead have it be application config option and simply have the default subscribers be configured by default.

[Aaron Patterson]

On Wed, Sep 19, 2012 at 11:00:32AM -0700, Brian Durand wrote:
> I've also just found a use case where I'd like to unsubscribe the default
> subscribers. I'd like to turn on INFO level logging for my application to
> get some better visibility into the running production application.
> However, the application gets a ton of traffic (100's of requests/second)
> and with the default subscribers the logs will fill up with gigabytes of
> data in a matter of minutes.
>
> What I think would make sense is to remove the static subscribe code from
> the LogSubscriber classes and instead have it be application config option
> and simply have the default subscribers be configured by default.

This makes sense to me. I think it would deal with Jeffrey's use case
as well. Can you put together a patch and we can discuss on a PR?

[Jeffrey Jones]

Groovy, I shall give it a go.

Cheers

Jeff