Configuration in Azure (Year of Azure–Week 14)

Another late post, and one that isn’t nearly what I wanted to do. I’m about a quarter of the way through this year of weekly updates and frankly, I’m not certain I’ll be able to complete it. Things continue to get busy with more and more distractions lined up. Anyways…

So my “spare time” this week has been spent looking into configuration options.

How do  know where to load a configuration setting from?

So you’ve sat through some Windows Azure training and they explained that you have the service configuration and you should use it instead of the web.config and they covered using RoleEnvironment.GetConfigurationSettingValue. So you know how to get a setting from with location? This is where RoleEnvironment.IsAvailable comes into play.

Using this value, we an write code that will pull from the proper source depending on the environment our application is running in. Like the snippet below:

if (RoleEnvironment.IsAvailable)
    return RoleEnvironment.GetConfigurationSettingValue("mySetting");
else
    return ConfigurationManager.AppSettings["mySetting"].ToString();

Take this a step further and you can put this logic into a property so that all your code can just reference the property. Simple!

But what about CloudStorageAccount?

Ok, but CloudStorageAccount has methods that automatically load from the service configuration. If I’ve written code to take advantage of this, they’re stuck. Right? Well not necessarily. Now you may have a seen a code snippet like this before:

CloudStorageAccount.SetConfigurationSettingPublisher(
    (configName, configSetter) =>
        configSetter(RoleEnvironment.GetConfigurationSettingValue(configName))
);

This is the snippet that needs to be done to help avoid the “SetConfigurationSettingPublisher needs to be called before FromConfigurationSetting can be used.” error message. But what is really going on here is that we are setting a handler for retrieving configuration settings. In this case, RoleEnvironment.GetConfigurationSettingValue.

But as is illustrated by a GREAT post from Windows Azure MVP Steven Nagy, you can set your own handler, and in this handler you can role your own provider that looks something like this:

public static Action<string, Func<string, bool>> GetConfigurationSettingPublisher()
{
    if (RoleEnvironment.IsAvailable)
        return (configName, configSetter) =>
      configSetter(RoleEnvironment.GetConfigurationSettingValue(configName));
    return (configName, configSetter) =>
        configSetter(ConfigurationManager.AppSettings[configName]);
}

Flexibility is good!

Where to next?

Keep in mind that these two examples both focus on pulling from configuration files already available to us. There’s nothing stopping us from creating methods that pull from other sources. There’s nothing stopping us from creating methods that can take a single string configuration setting that is an XML document and hydrate it. We can pull settings from another source, be it persistent storage or perhaps even another service. The options are up to us.

Next week, I hope (time available of course) to put together a small demo of how to work with encrypted settings. So until then!

PS – yes, I was renewed as an Azure MVP for another year! #geekgasm