How to do Logging in Phoenix/Elixir Apps?

[nelsonic]

Our apps deployed to Heroku have request and error logging included which is great.
But if we are going to deploy our apps to any infrastructure #59, logging is essential.

Story

As a developer
I want to have complete system and application logs
So that I can monitor aggregate usage of the app and understand issues when they appear.

As a product owner
I want application logging
So that I can see where faults appear
and get them fixed so people don't abandon the product!

Todo

• Research how to do Logging in Elixir/Phoenix Apps

  • https://hexdocs.pm/logger/Logger.html & https://hexdocs.pm/phoenix/Phoenix.Logger.html
  • https://stackoverflow.com/questions/30958616/how-to-log-in-controller-phoenix
  • https://timber.io/blog/the-ultimate-guide-to-logging-in-elixir

• Investigate our options for Open Source logging solutions. - the obvious advantage of running our own logging is privacy. We don't need to run any code that ships logs to a remote server outside of our control and there's far lower risk leaking any data.

• Read https://devcenter.heroku.com/articles/logging for details on Heroku logs

• Requirements for our Logging Solution

  • Logs should be viewable in near-realtime so they can be monitored during a request.
  • Logs should be viewable in a Web Browser (with authentication)
  • Ideally Logs should be viewable in a CLI with "tail"
  • Avoid logging any sensitive data such as PII or API keys etc.

Commercial Options

• While not Open Source, I think https://timber.io is worth considering as their Free tier is absurdly generous and they appear to be Elixir-focussed. see: https://timber.io/blog/the-ultimate-guide-to-logging-in-elixir/ and https://timber.io/pricing ... obvs Timber want to get people "hooked" so they will pay for the service, this is model used by many SaaS providers. I don't think we will have more than 1GB of logs for the foreseeable future. And provided we are strict with ourselves about not logging any sensitive data I think this could be a really good tool in the short/medium term.

[nelsonic]

Monitoring demystified: A guide for logging, tracing, metrics: https://techbeacon.com/enterprise-it/monitoring-demystified-guide-logging-tracing-metrics
This is currently top of HN: https://news.ycombinator.com/item?id=24006697