Metadata :function is not outputted by Logger.Formatter in Elixir 1.15

[ronaldwind]

Elixir and Erlang/OTP versions

Erlang/OTP 26 [erts-14.0.1] [source] [64-bit] [smp:20:20] [ds:20:20:10] [async-threads:1] [jit:ns]
Elixir 1.15.0 (compiled with Erlang/OTP 26)

Operating system

Ubuntu 22.04

Current behavior

It seems the special metadata :function is not outputted anymore in Elixir 1.15:

template = Logger.Formatter.compile("\n$time $metadata[$level] $message\n")
 
Logger.Formatter.format(
  %{
    level: :warn, 
    msg: {:string, "foo"}, 
    meta: %{
      mfa: {Logger.Formatter, :compile, 1}
    }
  }, 
  %Logger.Formatter{
    template: template, 
    metadata: [:module, :function, :mfa], 
    utc_log?: true, 
    truncate: 1000, 
    colors: %{enabled: false}
  }
)
|> IO.chardata_to_string()

results in :

"\n10:13:15.268 module=Logger.Formatter mfa=Logger.Formatter.compile/1 [warn] foo\n"

The :module and :mfa are outputted as expected, but the :function missing.

Expected behavior

I expect this output:

"\n10:13:15.268 module=Logger.Formatter function=compile/1 mfa=Logger.Formatter.compile/1 [warn] foo\n"

[josevalim]

function should work on old Elixir backends but it is no longer supported on the new backends/new formatter. It has been normalized in favor of mfa. :)

[ronaldwind]

Thanks, will migrate to mfa!

(The docs at https://github.com/elixir-lang/elixir/blob/main/lib/logger/lib/logger.ex#L133 and the code at https://github.com/elixir-lang/elixir/blob/main/lib/logger/lib/logger/formatter.ex#L210 suggest it should still work though :))

[josevalim]

You are right, it seems we ended-up adding support for them. I will investigate.