Chapter 7. Accessing logs on your Thorntail application

Procedure

1. Find the <dependencies> section in the pom.xml file of your application. Verify it contains the following coordinates. If it does not, add them.

   <dependency>
     <groupId>io.thorntail</groupId>
     <artifactId>logging</artifactId>
   </dependency>

2. If you want to log messages of a level other than INFO, launch the application while specifying the thorntail.logging system property:

   $ mvn thorntail:run -Dthorntail.logging=FINE

   See the org.wildfly.swarm.config.logging.Level class for the list of available levels.

1. Open a YAML profile file of your choice. If you do not know which one to use, open project-defaults.yml in the src/main/resources directory in your application sources. In the YAML file, add the following section:

   thorntail:
     logging:

2. Configure a formatter (optional). The following formatters are configured by default:

   PATTERN

   Useful for logging into a file.

   COLOR_PATTERN

   Color output. Useful for logging to the console.

   To configure a custom formatter, add a new formatter with a pattern of your choice in the logging section. In this example, it is called LOG_FORMATTER:

   pattern-formatters:
     LOG_FORMATTER:
       pattern: "%p [%c] %s%e%n"

3. Configure a file handler to use with the loggers. This example shows the configuration of a periodic rotating file handler. Under logging, add a periodic-rotating-file-handlers section with a new handler.

   periodic-rotating-file-handlers:
     FILE:
       file:
         path: target/MY_APP_NAME.log
       suffix: .yyyy-MM-dd
       named-formatter: LOG_FORMATTER
       level: INFO

   Here, a new handler named FILE is created, logging events of the INFO level and higher. It logs in the target directory, and each log file is named MY_APP_NAME.log with the suffix .yyyy-MM-dd. Thorntail automatically parses the log rotation period from the suffix, so ensure you use a format compatible with the java.text.SimpleDateFormat class.

4. Configure the root logger.

   The root logger is by default configured to use the CONSOLE handler only. Under logging, add a root-logger section with the handlers you wish to use:

   root-logger:
     handlers:
     - CONSOLE
     - FILE

   Here, the FILE handler from the previous step is used, along with the default console handler.