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Stack Exchange Utility Packages

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StackExchange.Utils.Http

Http is a helper class for making HttpClient calls. The send, deserialization, options, and verb portions are exchangable. Some examples:

POSTing a string and expecting a string:

var result = await Http.Request("https://example.com")
                       .SendPlaintext("test")
                       .ExpectString()
                       .PostAsync();

POSTing JSON and expecting protobuf back:

var result = await Http.Request("https://example.com")
                       .SendJson(new { name = "my thing" })
                       .ExpectProtobuf<MyType>()
                       .PostAsync();

Sending nothing and GETing JSON back:

var result = await Http.Request("https://example.com")
                       .ExpectJson<MyType>()
                       .GetAsync();

Sending nothing and GETing JSON back, with a timeout, ignoring 404 responses:

var result = await Http.Request("https://example.com")
                       .IgnoredResponseStatuses(HttpStatusCode.NotFound)
                       .WithTimeout(TimeSpan.FromSeconds(20))
                       .ExpectJson<MyType>()
                       .GetAsync();
// Handle the response:
if (result.Success)
{
    //result.Data is MyType, deserialized from the returned JSON
}
else
{
    // result.Error
    // result.StatusCode
    // result.RawRequest
    // result.RawResponse
}

Profiling

There are settings (.ProfileRequest and .ProfileGeneral) specifically for profiling - these are used and disposed around the events. By implementing IDisposable in something, you can time the events.

If you're using something like MiniProfiler, you can instrument HTTP calls in the default settings, like this:

var settings = Http.DefaultSettings;
settings.ProfileRequest = request => MiniProfiler.Current.CustomTiming("http", request.RequestUri.ToString(), request.Method.Method);
settings.ProfileGeneral = name => MiniProfiler.Current.Step(name);

StackExchange.Utils.Configuration

StackExchange.Utils.Configuration is a helper library that performs substitution and prefixing for IConfiguration-based configuration sources. It allows a value in the configuration tree to reference other values within the configuration system using a placeholder syntax ${key} or ${nested:key}. In addition, prefixing allows a "namespace" prefix to be applied to a subset of configuration, making it possible to segment configuration into logical areas.

This is particularly useful for storing secrets in a different, secure location but in a way that it makes it easy to compose configuration values like connection strings without dealing with it inside the application. E.g. consider the following files:

appsettings.json

{
    "ConnectionStrings": {
        "Database": "Server=srv01;Database=db01;User ID=${secrets:Database:UserId};Password=${secrets:Database:Password}"
    }
}

secrets.json

{
    "Database": {
        "UserId": "User123",
        "Password": "Password123!"
    }
}

This instructs the substitution provider to lookup the keys secrets:Database:UserId and secrets:Database:Password from the configuration system and replaces them in the value returned for ConnectionStrings:Database.

To support this a ConfigurationBuilder is configured as follows:

var configuration = new ConfigurationBuilder()
    .WithPrefix(
        "secrets",
        // everything in this configuration builder will be prefixed with "secrets:"
        c => c.AddJsonFile("secrets.json")
    )
    .WithSubstitution(
        // values in this configuration builder will have substitutions
        // replaced prior to being returned to the caller
        c => c.AddJsonFile("appsettings.json")
    )
    .Build();

Here we're loading a JSON file called secrets.json (it could equally be any source supported by the IConfiguration system - ideally something secure like Azure KeyVault or Hashicorp's Vault) and prefixing it with secrets:. Then, we load appsettings.json with support for substitutions. If a caller asks the IConfiguration that is produced for a connection string:

var connectionString = configuration.GetConnectionString("Database");

That value will be returned as Server=srv01;Database=db01;User ID=User123;Password=Password123!.

#### Substituting existing values In some cases it's useful to be able to substitute placeholders in existing strings. Support for that is provided by the SubstitutionHelper:

var configuration = new ConfigurationBuilder()
    .WithPrefix(
        "secrets",
        // everything in this configuration builder will be prefixed with "secrets:"
        c => c.AddJsonFile("secrets.json")
    )
    .Build();

var value = "Server=srv01;Database=db01;User ID=${secrets:Database:UserId};Password=${secrets:Database:Password}";
var valueWithSubstitution = SubstitutionHelper.ReplaceSubstitutionPlaceholders(value, configuration);

This will do exactly the same as if the value was substituted within the configuration system itself - the returned value will be Server=srv01;Database=db01;User ID=User123;Password=Password123!.

Notes

If a value has substitution placeholders that could not be replaced they are left intact - only placeholder keys that can be located in the configuration system are replaced.

License

StackExchange.Utils is licensed under the MIT license.

StackExchange/StackExchange.Utils

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