A way to enable logging - difficult to configure about cors_plug HOT 3 CLOSED

In the end, I'm not exactly certain where my configurations were wrong because I tried so many variations. But for anybody else facing this problem, the code has zero logging. What I ended up doing was editing deps/cors_plug/lib/cors_plug.ex, and putting |> IO.inspect into places around init and pulling up the configs, then running queries until I was able to find exactly how things matched. Difficult, but workable.

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I’ll glad you figured it out knowing full well how frustrating these things can be.

I would’ve recommended what you ended up doing anyway which is editing the source lib. I don’t think there’s a good way to add generic logging as in most cases it’d just be noise.

Thanks for sharing your journey tho, I’ll keep it in mind if there’s ever a discussion around or need for logging.

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@mschae I would suggest adding something to the docs around how to debug this. I know I've worked with others who've been equally frustrated. Even just instructions on how to do inline debugging. I.e. go to line ... and add |> IO.inspect, etc, if you are not seeing it match the output you are expecting.

What is most important:

• It only pays attention to the origin header -- which is client submitted and has no relation to conn.remote_ip. To see this add a debug |> IO.inspect to request_origin around line 159.
• Visually identify how that compares to what is actually coming into the configs, by adding something around the stages of init to verify your configurations are merging in correctly.

But honestly you could add debug/log function easily enough as a configuration option that logs these same things, then just add a default that disables it, where the config can add it in.

For whatever reason, I have noticed that the libs in Elixir are frighteningly low on debugging/logging capabilities. I suspect it's, in part, the nature of people wanting to optimize the pattern matching pipelines, without adding extra heuristics. But the side effect of this is a high barrier to entry for new developers, many I even know who just give up and go back to something a little more user-friendly.

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