Adding JSON formatted log feature

[syedimam0012]

What this is about?

This feature allows having JSON formatted (i.e. structured) logs. This means targeted querying and filtering can be performed in e.g. Grafana, Kibana, and similar dashboard tools.

Tested?

This has been tested in a local Kubernetes cluster using a modified fork branch of helm/charts/stable/chaoskube where I turned on this new feature as CLI option. You can see this modification here.

An example of the structured output is here:
{"level":"info","msg":"terminating pod","name":"compose-api-6fbc44c575-mm47c","namespace":"docker","time":"2019-01-25T05:14:50Z"}

What's next?

If this gets merged, I'll raise a pull request in relevant helm chart with the modified fork branch mentioned earlier.

[linki]

@syedimam0012 Thank you! I like that.

How about we change the flag from a bool to a selection list with the current behaviour as the default. ExternalDNS uses a --log-format flag that can be either text or json (and possibly more in the future). I believe it simply configures the LogFormatter like you already do. It seems simpler and more extensible to me.

[syedimam0012]

Thanks heaps for the kind response, @linki !

I agree that it makes more sense to update this to string options instead, which leaves room for future extensions. I do really appreciate for the example you've shared too.

The changes have just been committed upon testing all 3 possible cases that are default, text and json.

Please let me know if this requires further work.

I'll be happy to raise a relevant helm chart pr once this gets merged.

Best,
Syed

[linki]

Thanks for changing it.

If you use EnumVar instead of StringVar then kingpin will also do the validation for you. Any objection to using it?

[syedimam0012]

Pleasure and modified as advised, @linki!
Note: this has been tested in line with this helm repo pull-request. I'm yet to have those initial primary checks passed on that one.

[linki]

@syedimam0012 Thanks a lot!