# PlugLoggerWithMeta

PlugLoggerWithMeta is a [Plug.Logger](https://hexdocs.pm/plug/Plug.Logger.html) based on Plug.Logger code, focused on metadata logging.

## Why
Plug.Logger does not use [Logger.metadata](https://hexdocs.pm/logger/Logger.html#metadata/1),
so some useful information such as `method` and `request_path` are embedded into the log message
hence they must be scraped.

PlugLoggerWithMeta makes them machine readable by exporting them using Logger.metadata.

There are also other similar libraries, however this tries to behave as close as possible to `Plug.Logger`.

## Installation
- Add `:plug_logger_with_meta` dependency to your project's `mix.exs`:

```elixir
def deps do
  [
    {:plug_logger_with_meta, "~> 0.1"}
  ]
end
```
- Run `mix deps.get`

- Replace `Plug.Logger` with `PlugLoggerWithMeta`:

```diff
--- a/endpoint.ex
+++ b/endpoint.ex
@@ -38,7 +38,7 @@ defmodule MyProject.APIWeb.Endpoint do
   end
 
   plug Plug.RequestId
-  plug Plug.Logger
+  plug PlugLoggerWithMeta
```

- Add relevant metadata to your logger configuration:

```elixir
 config :logger, :console, format: "[$level] $message\n"
+  metadata: [
+    :method,
+    :request_path,
+    :status_code,
+    :elapsed,
+  ]
```

- Optional: use it with [pretty_log](https://github.com/ispirata/pretty_log) (or any other logger formatter/backend)

`pretty_log` will format all metadata using logfmt.

## Available Metadata

- elapsed (e.g. `22ms`)
- method (e.g. `GET`)
- request_path (e.g. `/v1/my/path`)
- status_code (e.g. `200`)
- tag (e.g. `got_client_req`, `sent_reply`)

## About This Project

This project has been created in order to provide better logs in [Astarte](https://github.com/astarte-platform/astarte).
We are open to any contribution and we encourage adoption of this library, also outside Astarte, in order to provide better logs to everyone.