UseSystemd should allow to create multi-line logs in journal

[kobruleht]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

ASP.NET Core 9 MVC application runs as a service in Debian and logs into a journal.

Program.cs:

using Microsoft.Extensions.Hosting.Systemd;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();

builder.Host.UseSystemd();

var app = builder.Build();
...

Logging from controller:

public class ContextLessLogger(ILogger<ContextLessLogger> syslog)
{
    public void Log() 
    {
        StringBuilder viga = new();
        viga.AppendLine("Line 1");
        viga.AppendLine("Line 2");
        syslog.Log(LogLevel.Warning, viga.ToString());
    }
}

journalctl shows Line 1 and Line 2 in single line:

veebr 12 22:33:52 myhost MyService[268922]: Eeva.Service.ContextLessLogger[0] Line 1  Line 2

Description in

https://learn.microsoft.com/en-us/dotnet/core/extensions/console-log-formatter

specifies that it always logs messages in a single line:

Systemd The ConsoleFormatterNames.Systemd console logger:

Uses the "Syslog" log level format and severities does not format
messages with colors Always logs messages in a single line

Describe the solution you'd like

Each li ne shoud appear as separate line in journal like other daemos do.
For example postgres creates multi line logs:

veebr 12 16:21:56 postgres[259580]: 2025-02-12 16:21:56 EET 1.2.3.3 stanislavs@sba ERROR:  permission denied >
                                    2025-02-12 16:21:56 EET 1.2.10.3 stanislavs@sba CONTEXT:  unnamed portal w>
                                    2025-02-12 16:21:56 EET 15.24.13.3 stanislavs@sba STATEMENT:  update kasutaj>
                                            where firmad='15' and kasutaja<>'LEAI' and $2  is distinct from 'Ja' >

journalctl output should be in two lines like in postgresql log:

veebr 12 22:33:52 myhost MyService[268922]: Eeva.Service.ContextLessLogger[0] Line 1  
                                                                              Line 2

Discussed in
https://stackoverflow.com/questions/79434420/how-to-write-multi-line-entry-to-linux-log

Additional context

No response

[martincostello]

Looks like this issue should be transferred to dotnet/runtime as it doesn't appear to be specific to ASP.NET Core as Console logging code is in that repository.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-extensions-logging
See info in area-owners.md if you want to be subscribed.