# Logger Backends JSON

Flexible JSON backend for Elixir Logger

## Installation

If [available in Hex](https://hex.pm/docs/publish), the package can be installed as:

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

    ```elixir
    def deps do
      [{:logger_backends_json, "~> 0.1.0"}]
    end
    ```

  2. Ensure `logger_backends_json` is started before your application:

    ```elixir
    def application do
      [applications: [:logger_backends_json]]
    end
    ```

## Configuration

```elixir
# A tuple with module and config name to use
config :logger, backends: [{Logger.Backends.JSON, :json}]

config :logger, :json,
  level: :info,
  metadata: %{application: "YourApp", env: "staging"},
  encoder: Poison
```

Or a bit more dynamic like

```elixir
config :logger, :json,
  level: fn() ->
    System.get_env("LOG_LEVEL") || "info"
  end,
  metadata: fn() -> [
      application: System.get_env("MY_APP_NAME"),
      env: System.get_env("APP_ENV")
    ]
  end,
  encoder: Poison
```

All possible options:

- `encoder` anything that implements `encode(object) :: map|list => {:ok, json}`, we test against `poison`, `exjsx` and `json` libs.
- `level` represents log level, same as in default `Logger` - `debug, info, warn, error`.
- `metadata` additional info to pass into json, should be `Map` in the end.

In any case you can also specify a function that will get evaluated on initialization.

If you need to pass any extra info on each log, i.e. some stuff from ETS tables or whatever, you can do it by creating custom encoder and adding it there.