There have been indeed some changes to Elixir’s Logger since v1.15.0:
[Logger] The :console configuration has been deprecated in favor of :default_formatter
[Logger] The :backends configuration has been deprecated in favor of Logger.add_handlers/1
Logger now uses :logger’s default handler and refers to the logger_std_h documentation, which states:
type = io:standard_io/0 | io:standard_error/0 | file | {device, io:device/0 } - Specifies the log destination.
The value is set when the handler is added, and it cannot be changed in runtime.
Defaults to standard_io, unless parameter file is given, in which case it defaults to file.
So once the require Logger is excuted in the one-liner, the default handler will have been added and its device cannot be changed during runtime. And looking at the actual
configuration of the default handler:
elixir -e 'require Logger; :logger.get_handler_config(:default) |> IO.inspect(); Logger.error("why stdout?")' 2>scr/delme
{:ok,
%{
id: :default,
module: :logger_std_h,
config: %{
type: :standard_io,
burst_limit_enable: true,
drop_mode_qlen: 200,
flush_qlen: 1000,
sync_mode_qlen: 10,
overload_kill_restart_after: 5000,
burst_limit_max_count: 500,
burst_limit_window_time: 1000,
overload_kill_enable: false,
overload_kill_mem_size: 3000000,
overload_kill_qlen: 20000,
filesync_repeat_interval: :no_repeat
},
level: :all,
filters: [remote_gl: {&:logger_filters.remote_gl/2, :stop}],
filter_default: :log,
formatter: {Logger.Formatter,
%Logger.Formatter{
template: ["\n", :time, " ", :metadata, "[", :level, "] ", :message, "\n"],
truncate: 8096,
metadata: [],
colors: %{
error: :red,
enabled: true,
info: :normal,
warning: :yellow,
debug: :cyan,
notice: :normal,
alert: :red,
critical: :red,
emergency: :red
},
utc_log?: false
}}
}}
08:53:01.187 [error] why stdout?
it is indeed using stdio.
