New style logging

https://blueprints.launchpad.net/sahara/+spec/new-style-logging

Rewrite Sahara logging in unified OpenStack style proposed by https://blueprints.launchpad.net/nova/+spec/log-guidelines

Problem description

Now log levels and messages in Sahara are mixed and don’t match the OpenStack logging guidelines.

Proposed change

The good way to unify our log system would be to follow the major guidelines. Here is a brief description of log levels:

• Debug: Shows everything and is likely not suitable for normal production operation due to the sheer size of logs generated (e.g. scripts executions, process execution, etc.).

• Info: Usually indicates successful service start/stop, versions and such non-error related data. This should include largely positive units of work that are accomplished (e.g. service setup, cluster start, successful job execution).

• Warning: Indicates that there might be a systemic issue; potential predictive failure notice (e.g. job execution failed).

• Error: An error has occurred and an administrator should research the event (e.g. cluster failed to start, plugin violations of operation).

• Critical: An error has occurred and the system might be unstable, anything that eliminates part of Sahara’s intended functionality; immediately get administrator assistance (e.g. failed to access keystone/database, plugin load failed).

Here are examples of LOG levels depending on cluster execution:

• Script execution:

LOG.debug("running configure.sh script")

• Cluster startup:

LOG.info(_LI("Hadoop stack installed successfully."))

• Job failed to execute:

LOG.warning(_LW("Can't run job execution {job} (reason: {reason}")).format(
            job = job_execution_id, reason = ex)

• HDFS can’t be configured:

LOG.error(_LE('Configuring HDFS HA failed. {reason}')).format(
          reason = result.text)

• Cluster failed to start:

LOG.error(_LE('Install command failed. {reason}')).format(
          reason = result.text)

Additional step for our logging system should be usage of pep3101 as unified format for all our logging messages. As soon as we try to make our code more readable please use {<smthg>} instead of {0} in log messages.

Alternatives

We need to follow OpenStack guidelines, but if needed we can move plugin logs to DEBUG level instead of INFO. It should be discussed separately in each case.

Data model impact

None

REST API impact

None

Other end user impact

None

Deployer impact

None

Developer impact

None

Sahara-image-elements impact

None

Sahara-dashboard / Horizon impact

None

Implementation

Assignee(s)

Primary assignee:

starodubcevna

Work Items

• Unify existing logging system

• Unify logging messages

• Add additional logs if needed

Dependencies

None

Testing

None

Documentation Impact

None

References

https://blueprints.launchpad.net/nova/+spec/log-guidelines https://www.python.org/dev/peps/pep-3101/