IIS7 GZIP Compression - httpCompression section - iis-7

Question

I trying to configure httpCompression on IIS7. By googling, I found that it can be made using httpCompression section in config. The problem, that I can't make it work from web.config.
When I make the configuration in applicationHost.config everything works as needed, but I want to be able to make this configuration per application and not globally.
I changed section definition in applicationHost.config to <section name="httpCompression" overrideModeDefault="Allow" /> and moved httpCompression section to web.config:
<httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files">
<scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" />
<staticTypes>
<add mimeType="text/*" enabled="true" />
<add mimeType="message/*" enabled="true" />
<add mimeType="application/x-javascript" enabled="true" />
<add mimeType="application/atom+xml" enabled="true" />
<add mimeType="application/xaml+xml" enabled="true" />
<add mimeType="*/*" enabled="false" />
</staticTypes>
<dynamicTypes>
<add mimeType="text/*" enabled="true" />
<add mimeType="message/*" enabled="true" />
<add mimeType="application/x-javascript" enabled="true" />
<add mimeType="application/json" enabled="true" />
<add mimeType="application/json; charset=utf-8" enabled="true" />
<add mimeType="*/*" enabled="false" />
</dynamicTypes>
</httpCompression>
What am I missing? It looks like IIS not reads compression configurations from web.config at all.
After each change, I make application pool recycle, so it not a problem.

Answer 1

as per this ServerFault answer: https://serverfault.com/a/125156/117212 - you can't change httpCompression in web.config, it needs to be done in applicationHost.config file. Here is the code I use in my Azure web role to modify applicationHost.config file and add mime types for compression:
using (var serverManager = new ServerManager())
{
var config = serverManager.GetApplicationHostConfiguration();
var httpCompressionSection = config.GetSection("system.webServer/httpCompression");
var dynamicTypesCollection = httpCompressionSection.GetCollection("dynamicTypes");
Action<string> fnCheckAndAddIfMissing = mimeType =>
{
if (dynamicTypesCollection.Any(x =>
{
var v = x.GetAttributeValue("mimeType");
if (v != null && v.ToString() == mimeType)
{
return true;
}
return false;
}) == false)
{
ConfigurationElement addElement = dynamicTypesCollection.CreateElement("add");
addElement["mimeType"] = mimeType;
addElement["enabled"] = true;
dynamicTypesCollection.AddAt(0, addElement);
}
};
fnCheckAndAddIfMissing("application/json");
fnCheckAndAddIfMissing("application/json; charset=utf-8");
serverManager.CommitChanges();
}
ServerManager comes from Microsoft.Web.Administration package in NuGet.

Answer 2

You should check the whole config file hierarchy.
If you removed the section from applicationHost you may be inheriting from machine.config or a web.config of a parent directory.