Akka SLF4J logback configuration and usage

Question

I have done the following steps to try and configure logging for my akka application:

• created an application.conf file and placed it in src/main/resources. It looks like:

  
      akka { 
        event-handlers = ["akka.event.slf4j.Slf4jEventHandler"] 
        loglevel = "INFO"
      }
  

• created a logback.xml file and placed it in src/main/resources. It looks like:

  <configuration>
  
    <appender name="FILE" class="ch.qos.logback.core.fileappender">
      <File>./logs/akka.log</File>
      <encoder>
        <pattern>%d{HH:mm:ss.SSS} [%-5level] %msg%n</pattern>
      </encoder>
    </appender>
  
    <root level="info">
      <appender-ref ref="FILE" />
    </root>
  
  </configuration>
  

• added the following to my .scala sbt build file:

  
  
      libraryDependencies += "com.typesafe.akka" % "akka-slf4j" % "2.0.3", 
      libraryDependencies += "ch.qos.logback" % "logback-classic" % "1.0.9"
      lazy val logback = "ch.qos.logback" % "logback-classic" % "1.0.9"
     

• attempted this code to log:

  
      import akka.event.Logging
  
      val log = Logging(context.system, this)
      log.info("...")
    

All I am getting is standard output logging, no log file creation with the logs.

Have I missed a step ? Or misconfigured something?

Answer 1

With this arrangement I can use an akka.event.Logging, no need to specify SLF4J instance.

(tested 13 Dec 2013)

I get console logging and logging to a file. To prove this is not built-in logger I changed to include %X{akkaTimestamp} as explained here:

http://doc.akka.io/docs/akka/snapshot/scala/logging.html

build.sbt

library dependencies: (Akka version 2.2.3)

...
"com.typesafe.akka" %% "akka-slf4j" % "2.2.3"
"ch.qos.logback" % "logback-classic" % "1.0.9"
...

src/main/resources/application.conf

akka {
  loggers = ["akka.event.slf4j.Slf4jLogger"]
  loglevel = "INFO"
}

src/main/resources/logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <target>System.out</target>
        <encoder>
            <pattern>%X{akkaTimestamp} %-5level[%thread] %logger{0} - %msg%n</pattern>
        </encoder>
    </appender>

    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>log/akka.log</file>
        <append>false</append>
        <encoder>
            <pattern>%date{yyyy-MM-dd} %X{akkaTimestamp} %-5level[%thread] %logger{1} - %msg%n</pattern>
        </encoder>
    </appender>

    <logger name="akka" level="INFO" />

    <root level="DEBUG">
        <appender-ref ref="CONSOLE"/>
        <appender-ref ref="FILE"/>
    </root>

</configuration>

This arrangement works when I use an ActorLogging mixin and also create a Logging directly:

import akka.event.Logging

val log = Logging(context.system, classOf[NameOfYourActor])

log.info("good luck!")

Answer 2

I came across this problem too but in my case it wasn't a matter of classpath.

I replaced akka.event.Logging with com.typesafe.scalalogging.slf4j.Logging and it works like a charm!

my logback.xml (under main/resource):

<configuration>
  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>logs/filename.log</file>
    <encoder>
      <pattern>%date %level %msg%n</pattern>
    </encoder>
    <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
      <maxIndex>10</maxIndex>
      <FileNamePattern>logs/filename.log.%i.gz</FileNamePattern>
    </rollingPolicy>
    <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
      <maxFileSize>20MB</maxFileSize>
    </triggeringPolicy>
  </appender>
  <root level="info">
    <appender-ref ref="FILE" />
  </root>
</configuration>

my pom.xml:

<dependency>
  <groupId>com.typesafe</groupId>
  <artifactId>scalalogging-slf4j_2.10</artifactId>
  <version>1.0.1</version>
</dependency>
<dependency>
  <groupId>ch.qos.logback</groupId>
  <artifactId>logback-classic</artifactId>
  <version>1.0.13</version>
</dependency>

and in the code:

import com.typesafe.scalalogging.slf4j.Logging

class LoggingService extends Actor with Logging {
  // use logger.info() etc.
}

(didn't use application.conf)

Answer 3

try using this application.conf:

akka {
  loggers = ["akka.event.slf4j.Slf4jLogger"]
  loglevel = "DEBUG"
  logging-filter = "akka.event.slf4j.Slf4jLoggingFilter"
}

I also have noticed that you probably have wrong class name in you logback config for file appender. You have <appender name="FILE" class="ch.qos.logback.core. fileappender"> but it should be <appender name="FILE" class="ch.qos.logback.core.FileAppender">.

Another issue may be the path to file. Try using absolute file path instead of relative. <file>/absolute/path/testFile.log</file>

You can also try to change logback version to 1.2.3. Here are akka docs on configuring sl4j: link

Answer 4

The only thing I would change in your setup is to add the weiglewilczek slf4j adapter.

I've got the following setup working just fine:

akka {
  event-handlers = ["akka.event.slf4j.Slf4jEventHandler"]
  loglevel = DEBUG
}

---

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>log/app.log</file>

        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>log/app.%d{dd-MM-yyyy}.log</fileNamePattern>
            <maxHistory>60</maxHistory>
        </rollingPolicy>

        <encoder>
            <pattern>%d [%thread] [%class] %5p - %m%n</pattern>
        </encoder>
    </appender>

    <root level="INFO">
        <appender-ref ref="FILE"/>
    </root>
</configuration>

---

trait test extends com.weiglewilczek.slf4s.Logging {
  def logIt() {
    logger.info("this logs fine")
  }
}