I have a Scala Maven project using that uses Spark, and I am trying implement logging using Logback. I am compiling my application to a jar, and deploying to an EC2 instance where the Spark distribution is installed. My pom.xml includes dependencies for Spark and Logback as follows:
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.7</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>1.7.7</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_${scala.binary.version}</artifactId>
<version>${spark.version}</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
When submit my Spark application, I print out the slf4j binding on the command line. If I execute the jars code using java, the binding is to Logback. If I use Spark (i.e. spark-submit), however, the binding is to log4j.
val logger: Logger = LoggerFactory.getLogger(this.getClass)
val sc: SparkContext = new SparkContext()
val rdd = sc.textFile("myFile.txt")
val slb: StaticLoggerBinder = StaticLoggerBinder.getSingleton
System.out.println("Logger Instance: " + slb.getLoggerFactory)
System.out.println("Logger Class Type: " + slb.getLoggerFactoryClassStr)
yields
Logger Instance: org.slf4j.impl.Log4jLoggerFactory@a64e035
Logger Class Type: org.slf4j.impl.Log4jLoggerFactory
I understand that both log4j-1.2.17.jar and slf4j-log4j12-1.7.16.jar are in /usr/local/spark/jars, and that Spark is most likely referencing these jars despite the exclusion in my pom.xml, because if I delete them I am given a ClassNotFoundException at runtime of spark-submit.
My question is: Is there a way to implement native logging in my application using Logback while preserving Spark's internal logging capabilities. Ideally, I'd like to write my Logback application logs to a file and allow Spark logs to still be shown at STDOUT.