# FileOnly Logger


A simple logger that writes messages to log files only (not to the console).
Elixir's Logger Backends were abandoned in favor of Erlang's Logger handlers.

## Installation


Add `file_only_logger` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:file_only_logger, "~> 0.2.0"}
  ]
end
```

Logger configuration may but _does not have_ to be set via config files.
See files `config/config.exs` and `config/config_logger.exs` as an example
(including log file rotation).

In the absence of any configuration, the default handler (`:default`) will
feature the following colors:

| Level    | Color         |
| -------- | ------------- |
| :debug   | :light_cyan   |
| :info    | :light_green  |
| :warning | :light_yellow |
| :error   | :light_red    |

Likewise without any configuration, the handlers below will log to their
corresponding files with a log rotation of 5 files (for example, the active file
"debug.log" plus 5 archives: "debug.log.0" up to "debug.log.4"):

| Level    | Handler          | File                |
| -------- | ---------------- | ------------------- |
| :debug   | :debug_handler   | "./log/debug.log"   |
| :info    | :info_handler    | "./log/info.log"    |
| :warning | :warning_handler | "./log/warning.log" |
| :error   | :error_handler   | "./log/error.log"   |

## Usage


Trying to log any message with severity less than the configured level will
simply cause the message to be ignored.

The configuration values for log level are:

- :all (default)
- :none
- [Levels](https://hexdocs.pm/logger/Logger.html#module-levels)

You may use file `config/runtime.exs` to configure the above log level:

```elixir
import Config

config :file_only_logger, level: :info
```

#### Example


```elixir
defmodule Log do
  use File.Only.Logger

  warning :error_occurred, {reason, file, env} do
    """
    \n'error' occurred...
    • Reason => '#{:file.format_error(reason)}'
    • File => #{Path.expand(file) |> inspect() |> maybe_break(10)}
    #{from(env, __MODULE__)}\
    """
  end
end

defmodule Check do
  def log_warning(file) do
    Log.warning(:error_occurred, {:enoent, file, __ENV__})
  end
end

Check.log_warning(__ENV__.file)
Check.log_warning("generate-line-break")
# will respectively log these lines in the configured log file(s):

2025-01-13 12:27:14.532 [warning]
'error' occurred...
• Reason => 'no such file or directory'
• File => "c:/Users/Ray/Documents/ex_dev/projects/file_only_logger/iex"
• App: undefined
• Module: Log
• Function: Check.log_warning/1

2025-01-13 12:30:46.370 [warning]
'error' occurred...
• Reason => 'no such file or directory'
• File =>
  "c:/Users/Ray/Documents/ex_dev/projects/file_only_logger/generate-line-break"
• App: undefined
• Module: Log
• Function: Check.log_warning/1
```

## Note


If you'd like to write a message to both the log files _and the console_,
simply change the macro to a function like so...

#### Example


```elixir
defmodule Log do
  use File.Only.Logger

  require Logger

  def warning(:error_occurred, {reason, file, env}) do
    Logger.warning("""
    \n'error' occurred...
    • Reason => '#{:file.format_error(reason)}'
    • File => #{Path.expand(file) |> inspect() |> maybe_break(10)}
    #{from(env, __MODULE__)}\
    """)
  end
end