.NET Core demo project for MTA deployment to Cloud Foundry

This demo project shows a very simple ASP.NET Web API service that returns hello world. It is secured with XSUAA from SAP BTP and can be deployed via mta.yaml to SAP BTP Cloud Foundry Environment.
It can be used as a template to build more complex multi-target that require a .NET module.

Securing your application with XSUAA

There is no standard NuGet package available (e.g. @sap/xssec for CAP NodeJS) to easily connect to the defined security configuration in xs-security.json, so this has to be done manually in the project.

Have a look in the Authentication folder to see how this can be done.

❗ The implementation is reverse engineered from @sap/xssec. Use at your own risk 😄 ❗

JSON logging to support Application Logging or Cloud Logging Service

Logging in JSON format is enabled via the Serilog library and active in productive environment.
For the logger property logger the triggering class name of the log event is used. The correlation_id is either taken from the request header x-correlation-id (e.g. if passed from another cf application) or a new UUID is created which will be added to each log message, that is created during a single request.

The project also contains a small CAP project to demonstrate the proper forwarding of the correlation_id when the .NET endpoint is called from CAP (see proxy-service.js).

Specifics for .NET Core MTA deployment

MTA.yaml

A workaround for the builder is required, as dotnet_core is no longer a recognized and valid application type.

In this sample we use the nodejs module type and overwrite the builder with a dummy echo command. As we use a source-based deployment, no build for the .NET module is required.
The actual build will be done via the buildpack during the set-up of the container.

modules:
  - name: my-dotnet-service-module
    type: nodejs
    path: <path-to-folder-with-.net-solution>
    build-parameters:
      builder: custom
      commands:
        - echo ">> Building .NET module"
    ...

Additionally, the online build pack for .NET has been removed in Nov 16, 2023 (SAP note 3364781), so we need to specify a valid one in the parameters section of the module.
The repository dotnet-core-buildpack in the Cloud Foundry org holds different releases. If you require a certain stack (i.e. concrete .NET Core version) you can use a specific release by adding the release tag after the repository url.

    ...
    parameters:
      buildpack: https://github.com/cloudfoundry/dotnet-core-buildpack.git#v2.4.27

Setting buildpack options

To define certain options for the used buildpack we need to create an additional file called buildpack.yml in the root path of the .NET module.

Here we can set the .NET version to be used:

---
dotnet-core:
  sdk: 8.0

Defining your main .NET project

If you have several projects in your module you need to specify your main project in a file .deployment at root level of the .NET module:

[config]
project = src/DemoService/DemoService.csproj

Build/Deployment to SAP BTP Cloud foundry

mbt build --mtar archive
# login to cloud foundry and choose space for deployment
# cf l
cf deploy mta_archives/archive.mtar

Testing the deployed service

Create .env file in folder /test, to execute the requests in api-test.http.

# Credentials of XSUAA instance
uaaUrl=https://...
clientId=
clientSecret=""

# URLS of deployed CAP and .NET modules
appUrl=https://...
capAppUrl=https://..

user_default_idp=
pw_default_idp=""

# If you have a custom IdP configured
user_custom_idp=
pw_custom_idp=""

Links

• Cloud Foundry docs | .NET Buildpack
• .NET Core CF Buildpack
• .NET CLI installation | Linux