Tracing/Logging

Thorium leverage tracing to accomplish logging. Tracing is very similar to logging but with several advantages:

• Unified trace/log viewing/aggregation
• Traces provide richer information then conventional logs

Unified Tracing

With conventional logging you are logging to a central file server or to disk (unless you feed your logs to elastic or another service). This means that when a problem occurs you may have to find the node that a service was running on to look at the logs. Then if the problem spans multiple nodes your are looking across multiple nodes trying to correlate logs. This is greatly exacerbated in Kubernetes as if an error takes down a pod then its logs can also be lost.

By leveraging tracing however we can log to both stdout and to a trace collector at once. This means that admins can look at logs normally but can also use the Jaeger webUI to view traces for all services in Thorium. Jaeger allows for admins to search for tags by any of the logged fields or by span type. This makes it much easier to locate problems in Thorium.

Richer Information

Exposing tracing in a webUI allows for much richer information to be exposed compared to conventional logging. This is largely because you can minimize what information is displayed at any given point unlike logs in a file. It also retains the parent child relationship of events allowing you to see that some action took place as part of a large action. The final aspect tracing provides over traditional logging is timing information. You can see how long actions take allowing you to find what operations are slow or causing problems.