View Source Tesla.Middleware.Logger (tesla v1.11.2)

Log requests using Elixir's Logger.

With the default settings it logs request method, URL, response status, and time taken in milliseconds.


defmodule MyClient do
  use Tesla

  plug Tesla.Middleware.Logger


  • :log_level - custom function for calculating log level (see below)
  • :filter_headers - sanitizes sensitive headers before logging in debug mode (see below)
  • :debug - show detailed request/response logging
  • :format - custom string template or function for log message (see below)

Custom log format

The default log format is "$method $url -> $status ($time ms)" which shows in logs like:

2018-03-25 18:32:40.397 [info]  GET -> 200 (88.074 ms)

It can be changed globally with config:

config :tesla, Tesla.Middleware.Logger, format: "$method $url ====> $status / time=$time"

Or you can customize this setting by providing your own format function:

defmodule MyClient do
  use Tesla

  plug Tesla.Middleware.Logger, format: &my_format/3

  def my_format(request, response, time) do
    "request=#{inspect(request)} response=#{inspect(response)} time=#{time}\n"

Custom log levels

By default, the following log levels will be used:

  • :error - for errors, 5xx and 4xx responses
  • :warn or :warning - for 3xx responses
  • :info - for 2xx responses

You can customize this setting by providing your own log_level/1 function:

defmodule MyClient do
  use Tesla

  plug Tesla.Middleware.Logger, log_level: &my_log_level/1

  def my_log_level(env) do
    case env.status do
      404 -> :info
      _ -> :default

Logger Debug output

When the Elixir Logger log level is set to :debug Tesla Logger will show full request & response.

If you want to disable detailed request/response logging but keep the :debug log level (i.e. in development) you can set debug: false in your config:

# config/dev.local.exs
config :tesla, Tesla.Middleware.Logger, debug: false

Note that the logging configuration is evaluated at compile time, so Tesla must be recompiled for the configuration to take effect:

mix deps.clean --build tesla
mix deps.compile tesla

In order to be able to set :debug at runtime we can pass it as a option to the middleware at runtime.

def client do
  middleware = [
    # ...
    {Tesla.Middleware.Logger, debug: false}


Filter headers

To sanitize sensitive headers such as authorization in debug logs, add them to the :filter_headers option. :filter_headers expects a list of header names as strings.

# config/dev.local.exs
config :tesla, Tesla.Middleware.Logger,
  filter_headers: ["authorization"]



@type log_level() :: :info | :warn | :warning | :error


@spec default_log_level(Tesla.Env.t()) :: log_level()