How to get application DEBUG and INFO messages properly logged in Play 2.4? - scala

Question

From Play 2.4 documentation, the default application logging level should be DEBUG, right:
<logger name="play" level="INFO" />
<logger name="application" level="DEBUG" />
However, in my logs I only get WARN and ERROR level messages.
For example this code:
class Application extends Controller {
val log = Logger(this.getClass)
def index = Action {
log.debug("debug")
log.info("info")
log.warn("warn!")
log.error("ERROR")
Ok("ok")
}
}
...only yields this in stdout (ditto in logs/application.log):
[warn] c.Application - warn!
[error] c.Application - ERROR
How to get application DEBUG and INFO messages properly logged?
Using Play 2.4.3, with basically default configs, and no conf/logback.xml at all. (SBT-based project setup, no Typesafe Activator.)
To clarify, I know I can create a custom config file (conf/logback.xml) for Logback. That is obvious from the documentation I linked to in the very first sentence.
The point here was: if my needs are extremely ordinary (get my app's messages logged, also debug and info), do I really need to create a lengthy custom configuration file? One would assume a thing as basic as this would work by default, or with some minimal config option. If you’ve paid attention, Play Framework is touted as one with good developer experience, and many things with it follow the “convention over configuration” principle.

Answer 1

What I learned from a colleague in our backend chat:
Your Application controller probably resides in the controllers
package, right? When you do Logger(getClass) <- getClass is used to
look up the package path to Application, which then would be
controllers.Application so you can for example add a line <logger
name="controllers" level="DEBUG" /> to get debug output from classes
in the controllers package
There is one way without custom configs (which worked for INFO but not DEBUG with a quick experiment). But it has significant drawbacks compared to using more granual loggers (as in my question).
The "application" logger is the default logger name that's used if you
use the Logger object directly, like Logger.info("Hello, world!"), as
opposed to creating your own instances
[...]
But that will clearly backfire quickly since then you lose granular
configuration of your logs and can only filter the logging "globally",
so I never use that.
Also, your logs will not disclose where the log statement is
made but instead just print that it's in "application"
I don't want those drawbacks, so I did create conf/logback.xml (starting with a copy of the default) and added custom loggers along the lines of:
<logger name="controllers" level="DEBUG" />
<logger name="services" level="DEBUG" />
<logger name="repositories" level="DEBUG" />
So now my val log = Logger(this.getClass) approach works.
But I fail to see how requiring 30-40 lines of custom XML for pretty much the most basic thing imaginable is good developer experience. If some Play advocate or developer could justify why this doesn't work out of the box with default config, I'd be interested in hearing that.

Answer 2

You have no .xml file at all inside the conf folder?
Adding this line should fix it for you:
<logger name="controllers" level="DEBUG" />
You can also override it on the application.conf file, although it will be deprecated in the future:
logger.controllers=DEBUG