[LOG4NET-604] UdpAppender does not resolve environment variables .Net Core

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.0.8
• Component/s: Appenders
• Environment: Asp.Net Core 2.1. Windows 7, MacOs 10.12.6
• Assignee: Unassigned
• Reporter: Sean E. Covel
• Created: 15/Jul/18 20:25
• Updated: 04/Apr/20 22:28

Description

I have a UdpAppender defined in a .Net Framework 4.5.2 and a .Net Standard (Asp.Net Core 2.1) project.

 

<appender name="UdpAppender" type="log4net.Appender.UdpAppender">
  <remoteAddress value="${LOGSERVER_HOST}" />
  <remotePort value="${LOGSERVER_PORT}" />
  <layout type="log4net.Layout.PatternLayout, log4net">
  <conversionPattern value="%d{yyyy-MM-dd'T'HH:mm:ss.fff'Z'} %-5p [%property\{server_name} %property\{service_name} %property\{service_port} %property\{CorrelationId}][%t] %c{5}:%L - %m%n"/>
  </layout>
</appender>

On .Net 4.5.2 the environment variable LOGSERVER_HOST and LOGSERVER_PORT are read and used by the appender.

In .Net Standard I get the following error:

log4net: Loading Appender [UdpAppender] type: [log4net.Appender.UdpAppender]
log4net:ERROR Could not create Appender [UdpAppender] of type [log4net.Appender.UdpAppender]. Reported error follows.
log4net.Util.TypeConverters.ConversionNotSupportedException: Cannot convert from type [System.String] value [${LOGSERVER_HOST}] to type
[System.Net.IPAddress] ---> System.Net.Sockets.SocketException: No such host is known
at System.Net.Dns.InternalGetHostByName(String hostName)
at System.Net.Dns.ResolveCallback(Object context)
— End of stack trace from previous location where exception was thrown —
at System.Net.Dns.HostResolutionEndHelper(IAsyncResult asyncResult)
at System.Net.Dns.EndGetHostEntry(IAsyncResult asyncResult)
at System.Net.Dns.<>c.<GetHostEntryAsync>b__27_1(IAsyncResult asyncResult)
at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Bool
ean requiresSynchronization)
— End of stack trace from previous location where exception was thrown —
at log4net.Util.TypeConverters.IPAddressConverter.ConvertFrom(Object source)
— End of inner exception stack trace —
at log4net.Util.TypeConverters.IPAddressConverter.ConvertFrom(Object source)
at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement element, Object target)
at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.ParseAppender(XmlElement appenderElement)
log4net:ERROR Appender named [UdpAppender] not found.

 

I have run the project on Windows 7 and MacOs 10.12.6.  The only way to get the UdpAppender to work on .Net Core is to hard-code the address and port in the xml configuration.