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Issue/Decision

Notes

Decision

1Are the logging guidelines set by the Logging Enhancement Project suitable for a cloud environment?

2Do we need a second appender for errors?
  • one file only

  • Later we will have a file to track who is accessing it, who is registering for the access...but we are not at that point yet
  • Within the log folder we could have multiple files for:

    • debug.log
    • audit.log
    • metric.log
    • error.log

    Logs will be archived each day.

Meeting Notes 11/12/20 

https://docs.onap.org/projects/onap-logging-analytics/en/latest/Logging_Enhancements_Project/logging_enhancements_project.html#id33

The logging enhancement team has proposed to split the log to multiple files: 

  • debug.log
  • audit.log
  • metric.log
  • error.log


Toine has suggested we follow this approach but exclude error logging. 


Before making anymore decisions we will investigate this project as we have some concerns about the logging standards in the logging enhancement project.

3The application should only logs to stdout and not in files?
  • By doing so we can leverage Kubernetes standard logging design.

  • If logging to files is provided, It would be good to also have a way to disable it to avoid file space management questions on worker nodes or pvc depending where logs files would be kept.

  • For monitoring, it is more complex to operate applications that are each one using specific logs files.

  • By having all applications logging to stdout, all logs can be collected in a common standard way and published and re-used anywhere that is convenient for any operations team (using filebeat or elk stack for example).

    See https://kubernetes.io/docs/concepts/cluster-administration/logging/ 


  • Whether user will be using Kubernetes / Azure or single manual deployment, features capability should be the same. We should not enforce to use anything specific to achieve the same service solution.
  • Many company enforce to  have those separate type of log files by security policy. Usually they store the audits logs ones.
    With log properties, you always can change the level log. And also alterate/disable the logs appenders at runtime.

Meeting Notes 11/12/20 

  • Everything a containerized application writes to stdout and stderr is handled and redirected somewhere by a container engine. For example, the Docker container engine redirects those two streams to a logging driver, which is configured in Kubernetes to write to a file in json format. - use a log rotation script

  • We want the logging to be easily configurable and allow for different implementations on how to collect logs. We will expose this configuration in the helm charts.  
  • Our default logging will be std out as it is easily configurable. 



4Is the file location ok?

 ../log/${logName}.log


I think this is ok. Logs will be placed in pods once deployed. 

I think we will need to set a property in our SpringBootApplication class for the log dir.


5Disk space

<property name="maxFileSize" value="20MB" />

Once the log reaches this value it is zipped.


6What kind of message should go with which level for logging?See 'Summary of each logging level' below
7How should we format our logs?logger.debug("No of Orders " + noOfOrder + " for client : " + client); 
logger.debug("No of Executions {} for clients:{}", noOfOrder , client); 

8Should we use is log.isDebugEnabled()?I think we should if the cost of performing the log is expensive - for example if we need to build a paramater in the log
9What logging framework to use?We are currently using slf4j
10What kind of information to log?
  1. Never log sensitive information as plain text 
  2. log all important information that is necessary to debug or troubleshoot a problem if it happens.

  3. Always log decision making statements e.g. the application loads some settings from a preference file and is unable to find the file 


Summary of each logging level

Log LevelImportance
FatalOne or more key business functionalities are not working and the whole system doesn’t fulfill the business functionalities.
ErrorOne or more functionalities are not working, preventing some functionalities from working correctly.
WarnUnexpected behavior happened inside the application, but it is continuing its work and the key business features are operating as expected.
InfoAn event happened, the event is purely informative and can be ignored during normal operations.
DebugA log level used for events considered to be useful during software debugging when more granular information is needed.
TraceA log level describing events showing step by step execution of your code that can be ignored during the standard operation, but may be useful during extended debugging sessions.

Appenders used by ONAP Projects 

Types of EELF Logs

EELF guidelines stipulate that an application should output log records to four separate files:

  1. audit
  2. metrics
  3. error
  4. debug



Excerpt from ONAP Application Logging Specification v1.3 (Frankfurt)

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