Windows Docker adding custom headers

Question

I am trying to add the X-Forwarded-For request header to the mcr.microsoft.com/dotnet/framework/aspnet:4.8-windowsservercore-ltsc2019 Docker base image using Add-WebConfigurationProperty.

My Dockerfile looks like:

FROM mcr.microsoft.com/dotnet/framework/aspnet:4.8-windowsservercore-ltsc2019
ARG source
RUN Add-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST' -filter "system.applicationHost/sites/site[@name='Default Web Site']/logFile/customFields" -name "." -value "@{logFieldName='X-Forwarded-For';sourceName='X-FORWARDED-FOR';sourceType='RequestHeader'}"

WORKDIR /inetpub/wwwroot
COPY ${source:-obj/Docker/publish} .

When I run docker build I get the following error

Sending build context to Docker daemon  4.096kB
Step 1/5 : FROM mcr.microsoft.com/dotnet/framework/aspnet:4.8-windowsservercore-ltsc2019
 ---> 30379ad7580b
Step 2/5 : ARG source
 ---> Using cache
 ---> 90c760c37d26
Step 3/5 : RUN Add-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST' -filter "system.applicationHost/sites/site[@name='Default Web Site']/logFile/customFields" -name "." -value @{logFieldName='X-Forwarded-For';sourceName='X-FORWARDED-FOR';sourceType='RequestHeader'}
 ---> Running in 4210cd6ae606
Add-WebConfigurationProperty : Expected an operator name (eg. 'and')
Input: get-config("MACHINE/WEBROOT/APPHOST")/system.applicationHost/sites/site[
@name=Default Web Site]/logFile/customFields
Position: 86
Length: 3
Fragment: Web
At line:1 char:76
+ ... yContinue'; Add-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APP ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Add-WebConfigurationProperty]
   , ArgumentException
    + FullyQualifiedErrorId : System.ArgumentException,Microsoft.IIs.PowerShel
   l.Provider.AddConfigurationPropertyCommand

The command 'powershell -Command $ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue'; Add-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST' -filter "system.applicationHost/sites/site[@name='Default Web Site']/logFile/customFields" -name "." -value @{logFieldName='X-Forwarded-For';sourceName='X-FORWARDED-FOR';sourceType='RequestHeader'}' returned a non-zero code: 1

The Dockerfile builds fine without the RUN Add-WebConfigurationProperty. If I build it without the RUN Add-WebConfigurationProperty I can run the container and execute the the Add-WebConfigurationProperty command and see that it does add the field to the log file. Any idea why it won't work via the Dockerfile.

Answer 1

I've run into some escaping issues with Windows Dockerfiles as well, sometimes I pull in a powershell script for things I need.

In this case since I assume you just want the field added, you can use:

-filter "system.applicationHost/sites/siteDefaults/logFile/customFields"

Hope this helps!

Thanks!