log initialization about dd-trace-js

[andrewsouthard1]

@gajus We've since added default startup logs in addition to debug logging: https://docs.datadoghq.com/tracing/troubleshooting/tracer_startup_logs/?tab=nodejs#startup-logs please reach out if you have any other questions!

[gajus]

Never mind, it looks like you have a {debug: true} configuration.

https://docs.datadoghq.com/tracing/setup/nodejs/#debug-mode

It would be handy to have all of this in README.md.

Generally, configuration such as debug/ logging should be controlled using environment variables rather than application variables. This way, a system admin can enable/ disable these settings without the need to redeploy the app.

[gajus]

Either way, looks like enabling debug does not log anything of value with regards to plugin loading issues.

[rochdev]

You can also set your own logger by using the logger option

Please let me know if you think anything is missing from the debug logs! We went with a minimal approach to start and only logged the components that are the most difficult to debug.

Currently which plugin is loaded is not included, but I agree it would be very helpful.

Are you importing express and pg before initializing the tracer? This is usually the only reason a plugin would not be loaded. Also note that hoisting can happen when transpiling with Babel.

[rochdev]

Actually the version could also be a cause, and this should be logged as well if there is a version mismatch.

[gajus]

Either way, looks like enabling debug does not log anything of value with regards to plugin loading issues.

There is DD_TRACE_DEBUG setting.

https://github.com/DataDog/dd-trace-js/blob/master/src/config.js#L11-L20

[gajus]

Actually the version could also be a cause, and this should be logged as well if there is a version mismatch.

That is the case indeed. Yes, this should be logged.