Startup.cs error (ASP.Net Core configuration) - configuration

Question

I am trying to set up an ASP.Net Core application to read in configuration settings from a json file. I am using VS2015 and .NetCore 1.0 (with .Net Core Tools preview 2). I am having problems getting a simple piece of boiler plate code to compile.
I am using the following code, which was published at
http://asp.net-hacker.rocks/2016/03/21/configure-aspnetcore.html
public Startup(IHostingEnvironment env)
{
// Set up configuration sources.
var builder = new ConfigurationBuilder()
.AddJsonFile("appsettings.json")
.AddEnvironmentVariables();
if (env.IsDevelopment())
{
// This will push telemetry data through Application Insights
// pipeline faster, allowing you to view results immediately.
builder.AddApplicationInsightsSettings(developerMode: true);
}
Configuration = builder.Build();
}
However, the IDE/compiler complains that 'the name "Configuration" does not exist in the current context' (last line of code). The only suggestion from the IDE is to include Microsoft.Extensions.Configuration. However this is a namespace which does not contain an object or property named "Configuration".
In addition 'AddApplicationInsightsSettings' fails with does IConfigurationBuilder not contain a definition for AddApplicationInsightsSettings and no extension method AddApplicationInsightsSettings accepting a first argument of type IConfigurationBuilder could be found
Any suggestions please ?
Thanks

Answer 1

Simply add Configuration property to your Startup class, tutorial has missed this 'step':
public IConfigurationRoot Configuration { get; set; }
ConfigurationBuilder.Build() method just returns instance of IConfigurationRoot, that you should save, if need to get settings further in Startup class (in ConfigureServices method for example).
Regarding second error, looks like you didn't add the Application Insights dependency:
{
"dependencies": {
"Microsoft.ApplicationInsights.AspNetCore": "1.0.0"
}
}