Thoughts about errors & logging

thoughts.md

When an error occurs in a function and there is no expectation that the caller can deal with it, returning {:error, error} feels noisy.

Is this better? It makes the assumption that the caller doesnt care. The error is logged for a human operator to see.

def get_some_pods() do
  response = Client.get_pods()
  
  case response do
    {:ok, pods} -> pods
    {:error, error} ->
      Logger.error(error)
      []
  end
end

Should the caller be given the option to respond?

def get_some_pods() do
  response = Client.get_pods()
  
  case response do
    {:ok, pods} -> pods
    {:error, error} ->
      Logger.error(error)
      {:error, error}
  end
end

def caller() do
  case get_some_pods() do
    {:ok, pods} -> do_something_with(pods)
    _ -> 
      # caller may not care, but at least it has the option
      do_something_with([])
  end
end

Not sure how I feel about the noise. I guess it depends on if the caller could find use in the error.

If its something like an intermitting HTTP request that occassionally fails because of a flakey upstream API, why should my caller care? It'll run again in a few minutes or backoff/jitter (use the error). 🤷

It should always be the erroring functions responsibility to do the logging, but in a library, this can be noisy or an incompatible format with the applications logger.

This sucks:

{my: "lovely", json: {log: "messages"}
{my: "lovely", json: {log: "messages"}
{my: "lovely", json: {log: "messages"}
{my: "lovely", json: {log: "messages"}
{my: "lovely", json: {log: "messages"}
HAHAHA IM A DEPENDENT APPLICATION FUCK YOU STDOUT/STDERR
{my: "lovely", json: {log: "messages"}
{my: "lovely", json: {log: "messages"}

Instead, use telemetry to dispatch error events and supply a default log_handler/4 for logging that the top level application can optionally use, or at least bind the error events to its own log formatter.