The component should conform to the ONAP Logging Specification format.   

See the Active Logging Specification page for up-to-date specs.   

At the time of writing, the active logging specification is the  Casablanca v1.2.

Per the current spec, 4 levels of compliance are supported (see specification):

• L0: Log Specification unchanged
• L1: Log Specification compliance via local project changes, library, or wrapper.
• L2: Log Specification compliance via SLF4J supplied logging-analytics library.
• L3: Log specification compliance via AOP library over SLF4J supplied logging-analytics library.

It would be up to the component to support the appropriate level of compliance > L0.   For components that uses an existing logging infrastructure and is not convenient to adapt the one provided from the logging team, L1 makes the most sense.   Note that the logging reference implementation loses some precision with regards to some pattern layout flags, and may imply using interfaces that differ the standard slf4j.

The spec does not clearly mention at this point the presence of audit/metrics/error/debug log files, but will move on with the assumption of the presence of these files with the assumption that these files should be preserved.    The audit, error, and metrics files should comply with the specification as they could be considered for end-to-end ONAP operator interested in analyzing end-to-end transactions, but for our purposes.