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# Svadilfari

A logger backend for sending logs directly to Grafana Loki.

## Installation

The package can be installed by adding `svadilfari` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:svadilfari, "~> 0.1"}
  ]
end
```

Configure some parameters:

```elixir
config :logger, :backends, [:console, Svadilfari]

config :logger, :svadilfari,
  metadata: [:user_id, :bogons],
  max_buffer: 10,
  client: [
    url: "http://localhost:3100",
    opts: [
      org_id: "tenant1"
    ]
  ],
  labels: [
    {"service", "svadilfari"},
    {"env", "dev"}
  ]
```

and start sending logs to Loki!

## Configuration

A majority of configuration values works just like the `:console` logger, and more in-depth information on their function can be found [here](https://hexdocs.pm/logger/1.13.4/Logger.Backends.Console.html#module-options):

* `level`: The log level.
* `format`: The format message used to print logs. Defaults to `"\n$time $metadata[$level] $levelpad$message\n"`.
* `metadata`: The metadata to be printed by `$metadata`.
* `max_buffer`: Maximum events to buffer while waiting for Loki to respond. Defaults to 32. Once full, the backend will block until Loki returns a success or error.

There are a few Loki-specific parameters:

* `labels`: A list of `{String.t(), String.t()}` tuples that represents Loki labels.
* `client`: 
  * `url`: The Loki URL to send to. The `/loki/api/v1/push` path is inferred.
  * `opts`: Svadilfari uses the Sleipnir Loki client under the hood. [Sleipnir Tesla Client](https://hexdocs.pm/sleipnir/readme.html#customizing-the-client) args can be passed here.