Debugging Elixir in Production - Workshop

Join the Elixir Fire Brigade - Level-up Your Elixir Debugging Skills

Both Erlang and Elixir are praised for their "debuggability". It's true - there's a lot of tools and techniques that can be used, even on live, production systems. Not only that - they are easily accessible and freely usable. Together we're going to explore them in depth.

We're going to learn what exactly happens when you call a GenServer, how to "spy" on processes and introspect the VM internals. We're going to work with an example application - a basic key-value store built on top of plug, prepare a release for it and deploy it to production. Unfortunately, after the deployment we're going to discover some errors, we didn't anticipate. Fortunately, with the knowledge we gained earlier, we'll be able to diagnose and fix them - live in production!

Attendees should be familiar with syntax and basic features of either Elixir or Erlang. It is advised that all attendees complete the "Mix and OTP tutorial" before the workshop. Link is here: http://elixir-lang.org/getting-started/mix-otp/introduction-to-mix.html

Participants should have Elixir >= 1.3 and Erlang >= 18 locally installed, together with their favorite editor.

Editions

• ElixirConf EU (Barcelona, 2017)

Prerequisites

• Erlang - verified with 18.3 and above.
• Elixir - verified with 1.3 and above.
• Phoenix - verified with 1.3 and above.

For managing multiple Erlang and Elixir versions we recommend asdf.

How to using this workshop?

Moving through bugs

If you want to tackle particular bug just move to a specific tag:

production-debugging-workshop.ex $ git checkout BUG_1

If you want to check how it was fixed, move to the corresponding tag with a fix:

production-debugging-workshop.ex $ git checkout FIX_1

In order to see how it was solved just type one of those commands:

production-debugging-workshop.ex $ git diff BUG_1..FIX_1
production-debugging-workshop.ex $ git show FIX_1

Explanation why and how to debug and narrow it down is inside materials.

Helpers

Feel free to use prepared helpers and scripts that will ease your pain when using this repository (please keep in mind that scripts requires curl). You will find them in the helpers directory which contains:

• Markdown cheat-sheet with helpful tools and commands used during workshop (helpers/commands.md).
• Scripts for executing curl commands (using REST API).
  • If you do not like command line - do not worry, we have prepared exported version of those API calls compatible with Advanced REST Client.
    • Unfortunately it is Google Chrome / Chromium only add-on - PR for other browsers are welcomed! 😄

Materials

If you were on one of editions mentioned above you should receive materials after the workshop in a dedicated email from us. Unfortunately rest of people will have to wait - stay tuned. 😉

Authors

• @afronski
• @mentero
• @michalmuskala