Changing cloud service web.config at runtime

Question

I'm trying to change the web.config of a deployed cloud service (WCF in this case) on Windows Azure, and when I try to change the appSettings in the web.config at runtime, I'm getting permission denied error:

Access to the path 'E:\sitesroot\0\web.config' is denied.

Is there a way to fix this?

Answer 1

Jonny S is right. You should store settings you want to change at runtime in the role configuration. The web.config changes will be lost if Azure moves your VM and in a multi-instance scenario your instances will be out of sync. You can use roleenvironmentchanging event to manage how a role instance responds to a configuration change.

For more info on roleenvironmentchanging event check http://msdn.microsoft.com/en-us/library/windowsazure/gg432963.aspx

Answer 2

You should store any settings you need to change at runtime in the ServiceConfiguration (cscfg) of your Role and then use the following in your code to retrieve the setting:

string setting = RoleEnvironment.GetConfigurationSettingValue("myConfigSetting");

You can change the values in the ServiceConfiguration through the Management Portal once deployed.

Answer 3

If you RDP into the web role you should be able to add permissions to the web.config file for the logged in user. You can then modify the web.config. As @Adil mentions this will cause the AppDomain to recycle so should only really be done as a last resort.