The Buildpack logs to both
<app dir>/.buildpack-diagnostics/buildpack.log and standard error.
Logs are filtered according to the configured log level.
If the buildpack fails with an exception, the exception message is logged with a
log level of ERROR whereas the exception stack trace is logged with a log
level of DEBUG to prevent users from seeing stack traces by default.
The Buildpack logs sensitive information, such as environment variables which may contain security credentials.
Note: Be careful not to expose the sensitive information, for example
by posting standard error stream contents or the contents of <app dir>/.buildpack-diagnostics/buildpack.log to a public discussion
list.
The LoggerFactory class in the LibertyBuildpack::Diagnostics module
manages a single instance of a subclass of the standard Ruby Logger.
The Buildpack class creates a logger which is shared
by all other classes and which is retrieved from the LoggerFactory as necessary:
logger = LoggerFactory.get_logger
This logger is used in the same ways as the standard Ruby logger and supports both parameter and block forms:
logger.info('success')
logger.debug { "#{costly_method}" }
For general information on configuring the Buildpack, refer to Configuration and Extension.
You can set the $JBP_LOG_LEVEL environment variable to configure the log level. There are five logs levels:
DEBUG | INFO | WARN | ERROR | FATAL
For example:
cf set-env <app name> JBP_LOG_LEVEL DEBUG
If JBP_LOG_LEVEL is not set, the default log level is read from the configuration in
config/logging.yml.
You can use any mixture of upper and lower case letters to specify the logging levels in the JBP_LOG_LEVEL environment variable and the config/logging.yml file.
If you do not set the JBP_LOG_LEVEL environment variable, the Ruby verbose and debug modes override the default log level and change it to DEBUG.