apache-flink logging Using a logger in your code
Example
Add the slf4j dependency to your pom.xml:
<properties>
<slf4j.version>1.7.21</slf4j.version>
</properties>
<!-- ... -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
Create a logger object for use in your class:
private Logger LOGGER = LoggerFactory.getLogger(FlinkApp.class);
In classes that need to be serialized, such as subclasses of RichMapFunction, don't forget to declare LOGGER as transient:
private transient Logger LOG = LoggerFactory.getLogger(MyRichMapper.class);
In your code, use LOGGER as usual. Use placeholders ({}) to format objects and such:
LOGGER.info("my app is starting");
LOGGER.warn("an exception occurred processing {}", record, exception);
