Martin Storø Nyfløtt created LOG4NET-658:
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Summary: ColoredConsoleAppender throws exception on .NET Core
Key: LOG4NET-658
URL: https://issues.apache.org/jira/browse/LOG4NET-658
Project: Log4net
Issue Type: Bug
Components: Appenders
Affects Versions: 2.0.8
Environment: Windows, .NET Core 3.1
Reporter: Martin Storø Nyfløtt
Moving from .NET Framework to .NET Core, I discovered that
ColoredConsoleAppender starts logging the following error messages to my
console if I reference it in a log4net.config:
{noformat}
log4net:ERROR Could not create Appender [ColoredConsoleAppender] of type
[log4net.Appender.ColoredConsoleAppender]. Reported error follows.
System.NotSupportedException: No data is available for encoding 437. For
information on defining a custom encoding, see the documentation for the
Encoding.RegisterProvider method.
at System.Text.Encoding.GetEncoding(Int32 codepage)
at log4net.Appender.ColoredConsoleAppender.ActivateOptions()
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.ParseAppender(XmlElement
appenderElement)
log4net:ERROR Appender named [ColoredConsoleAppender] not found.{noformat}
The reason I am seeing this is because [ColoredConsoleAppender will
call|https://github.com/apache/logging-log4net/blob/rel/2.0.12/src/log4net/Appender/ColoredConsoleAppender.cs#L462]
GetConsoleOutputCP() in Kernel32.dll to get the current encoding being used in
the console to configure a stream writer for writing to the console with the
appropriate text encoding. In my case, this is 437 (OEM United States). When
GetEncoding with this code-page, the exception above gets thrown because this
encoding is not included out-of-the-box in .NET Core.
This can be reproduced by having an application with the following Main:
{code:java}
static void Main()
{
var configurationPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory,
"log4net.config");
XmlConfigurator.Configure(new FileInfo(configurationPath));
}
{code}
and the following log4net.config:
{noformat}
<?xml version="1.0" encoding="utf-8"?><log4net>
<appender name="ColoredConsoleAppender"
type="log4net.Appender.ColoredConsoleAppender">
</appender> <root>
<appender-ref ref="ColoredConsoleAppender" />
</root>
</log4net>{noformat}
In order to go around this problem, I have added a reference to the Nuget
package
[System.Text.Encoding.CodePages|https://www.nuget.org/packages/System.Text.Encoding.CodePages/]
and registered the code pages before I configure log4net:
{code:java}
static void Main()
{
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
var configurationPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory,
"log4net.config");
XmlConfigurator.Configure(new FileInfo(configurationPath));
}
{code}
I think this is also how you would fix this in log4net. This is also a
show-stopper from getting this functionality working on Linux (or anything
non-Windows), since Kernel32.dll is a Windows-specific library.
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