LoggerJsonFileBackend
===

LoggerJsonFileBackend is elixir `logger` backend that writes json logs to a file.

Configuration
---

This logger backend provides follow options:

| name         | description |
| ------------ | ----------- |
| path         | log file path. this option is "MUST" |
| level        | minimum logging level. default is `:info` | 
| metadata     | included metadata keys list. detault is empty list |
| json\_encoder | using json encoder. default [poison](https://github.com/devinus/poison) |

You need to add logger backend setting

```
config :logger,
  backends: [{LoggerJSONFileBackend, :log_name}]

config :logger, :log_name,
  path: "/var/log/my_app/app.log"
  level: :info
  metadata: [:request_id, :user_id, :req_params]
  json_encoder: JSON # or Poison
```