Dropwizard application not using log config from configuration.yml

Question

I am trying to get DropWizard to log to an output file. The file is being created but nothing written to it.

In fact it would appear that the configuration in the provided .yml file is not being used.

I am also getting the following warnings during startup, not sure if they are related:

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Users/conor/.m2/repository/ch/qos/logback/logback-classic/1.1.3/logback-classic-1.1.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/Users/conor/.m2/repository/com/conor/project/project-common/0.1-SNAPSHOT/project-common-0.1-SNAPSHOT.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.

How can I get dropwizard to pickup the logging config in the yml provided at startup and how can I figure out where the current config is coming from? Thanks.

UPDATE::

I am running DropWizard v0.9.1 and my logging configuration is as follows:

# Logging settings.
logging:

  # The default level of all loggers. Can be OFF, ERROR, WARN, INFO, DEBUG, TRACE, or ALL.
  level: TRACE

  # Logger-specific levels.
  loggers:

#     Sets the level for 'com.example.app' to DEBUG.
    io.dropwizard: INFO

#     Redirects SQL logs to a separate file
    org.hibernate.SQL:
      level: DEBUG

# Logback's Time Based Rolling Policy - archivedLogFilenamePattern: /tmp/application-%d{yyyy-MM-dd}.log.gz
# Logback's Size and Time Based Rolling Policy -  archivedLogFilenamePattern: /tmp/application-%d{yyyy-MM-dd}-%i.log.gz
# Logback's Fixed Window Rolling Policy -  archivedLogFilenamePattern: /tmp/application-%i.log.gz

  appenders:
    - type: console
    - type: file
      threshold: DEBUG
      logFormat: "%-6level [%d{HH:mm:ss.SSS}] [%t] %logger{5} - %X{code} %msg %n"
      currentLogFilename: output/logs/dropwizard.txt
      archivedLogFilenamePattern: output/logs/dropwizard-%d{yyyy-MM-dd}-%i.txt.gz
      archivedFileCount: 10
      timeZone: UTC
      maxFileSize: 10MB

Answer 1

This looks like a typical SLF4J binding issue and is solved easily. First take a look at the relevant section in the URL provided with the warning for an explanation.:

The warning emitted by SLF4J is just that, a warning. Even when multiple bindings are present, SLF4J will pick one logging framework/implementation and bind with it. The way SLF4J picks a binding is determined by the JVM and for all practical purposes should be considered random. As of version 1.6.6, SLF4J will name the framework/implementation class it is actually bound to. Embedded components such as libraries or frameworks should not declare a dependency on any SLF4J binding but only depend on slf4j-api. When a library declares a compile-time dependency on a SLF4J binding, it imposes that binding on the end-user, thus negating SLF4J's purpose. When you come across an embedded component declaring a compile-time dependency on any SLF4J binding, please take the time to contact the authors of said component/library and kindly ask them to mend their ways.

Since the binding choice is random, my guess is that the project-common SLF4J dependency is being bound and not the intended one from logback-classic, a transitive dependency of dropwizard. You should either exclude the one in the project-common in your Maven pom file or better yet, if you have access to the code to project-common, remove it from the pom file as the linked-to web page suggests (i.e. "mend their ways").