Kanject.Core.Api.Aws.Extensions 3.8.3

Kanject.Core.Api.Aws.Extensions

Kanject.Core.Api.Aws.Extensions adds AWS-specific plumbing for ASP.NET Core services and Lambda functions: loading configuration from AWS Systems Manager Parameter Store, turning PrintInConsole output into single-line JSON that CloudWatch Logs Insights can query, and reading the caller's country code from CDN headers.

Installation

dotnet add package Kanject.Core.Api.Aws.Extensions

Targets .NET 8, .NET 9 and .NET 10. It depends on Amazon.Extensions.Configuration.SystemsManager, AWSSDK.SimpleSystemsManagement and Kanject.Core.Api.Abstractions.

Quick start

using Kanject.Core.Api.Aws.Extensions.PrintInConsole;
using Kanject.Core.Api.Aws.Extensions.Vault.ParameterStore;

var builder = WebApplication.CreateBuilder(args);

#if DEBUG
// Local: path, profile and region come from appsettings (AppSettings section).
builder.AddAwsSystemManagerParameterStore(fetchSecretPathFromAppSettings: true);
#else
// Deployed: path comes from the SECRET_PARAMETER_PATHNAME environment variable.
builder.AddAwsSystemManagerParameterStore();
#endif

builder.Services.AddPrintInConsoleCloudWatch(options => options.ServiceName = "orders-api");

var app = builder.Build();
app.Run();

Parameter Store configuration

AddAwsSystemManagerParameterStore loads every parameter under a path into IConfiguration using Amazon.Extensions.Configuration.SystemsManager. The path prefix is stripped and the remaining / segments become :, so /orders-api/prod/Database/ConnectionString under the path /orders-api/prod/ is read as configuration["Database:ConnectionString"].

Each form exists on both WebApplicationBuilder and IConfigurationBuilder (use the latter in Lambda functions that build configuration without a web host):

For the app-settings form, the values are read from the configuration built so far; pass an IConfiguration as the second argument to read them from somewhere else:

{
  "AppSettings": {
    "SecretParameterPathName": "/orders-api/dev/",
    "AwsProfile": "dev",
    "AwsRegion": "eu-west-2"
  }
}

The app-settings and explicit forms require a named AWS profile, which makes them a fit for local development; in Lambda or containers use the environment-variable form so the SDK's default credential chain applies. The app-settings and explicit forms throw at startup when a required value is missing; the environment-variable form does not check the variable itself, so make sure it is set.

CloudWatch-friendly PrintInConsole

PrintInConsole (from Kanject.Core) writes plain text by default. AddPrintInConsoleCloudWatch() routes it through a handler that writes one JSON object per line — the format CloudWatch Logs Insights discovers fields from automatically — so existing call sites need no changes.

1. Enable the interceptor in the project that makes the calls

<PropertyGroup>
  <EnablePrintInConsoleInterceptor>true</EnablePrintInConsoleInterceptor>
</PropertyGroup>

The routing is done by a compile-time interceptor generator from Kanject.Core.Annotations. Only PrintInConsole calls compiled in a project with this property set are routed; calls compiled elsewhere keep the default console output.

2. Register the handler

using Kanject.Core.Api.Aws.Extensions.PrintInConsole;

builder.Services.AddPrintInConsoleCloudWatch(options =>
{
    options.ServiceName = "payment-api";   // added to every entry
    options.IncludeData = true;             // set false to drop the data array
});

The handler is installed by a hosted service when the host starts and removed when it stops; calls made before startup (for example while building configuration) use the default output.

Output

using Kanject.Core.SystemConsole.Extensions;

"Cache performance".PrintInConsole(tag: "Performance", data: new object[] { new { HitRate = 0.94 } });

{"timestamp":"2026-03-20T10:30:02.0000000Z","level":"Information","message":"Cache performance","tag":"Performance","service":"payment-api","data":[{"hitRate":0.94}]}

Severity

The interceptor generator infers level at compile time: calls inside a catch block or with an Exception argument become Error, and error/warning/debug keywords in the tag or string literal select the matching level; everything else is Information. Pass a level explicitly to override the inference:

using Kanject.Core.SystemConsole;
using Kanject.Core.SystemConsole.Extensions;

"Error code lookup table loaded".PrintInConsole(ConsolePrintLogLevel.Information);

Example Logs Insights queries

fields @timestamp, level, message, tag, service
| filter level = "Error"
| sort @timestamp desc
| limit 50

stats count(*) as errorCount by service
| filter level = "Error"
| sort errorCount desc

ILogger bridge or CloudWatch JSON?

Kanject.Core also offers services.AddPrintInConsoleLogging(), which forwards PrintInConsole to ILogger. Use that when the application already has logging providers configured; use AddPrintInConsoleCloudWatch() for Lambda functions that write straight to CloudWatch without a logging framework. Don't register both — each replaces the same static handler, and the last one to start wins.

Client country code

using Kanject.Core.Api.Aws.Extensions.Controller;

var country = this.GetClientCountryCode();   // inside a controller action

GetClientCountryCode() returns the first header present among X-Country, CloudFront-Viewer-Country and CF-IPCountry, or null. These headers are only trustworthy when your CDN or load balancer sets or overwrites them — a client can send any of them directly.

Public surface at a glance

Related packages

License

Licensed under the Kanject Code Libraries License Agreement (KCLLA); the full text ships in this package as LICENSE.md. Organizations whose trailing-twelve-month gross revenue and total funding raised are each below US$250,000 may use it at no cost under the Free Tier. At or above either threshold a commercial license is required — contact commercial@kanjectbusiness.com.