richlander

Modernizing a codebase for C# 9

There are lots of cases that you can improve. The examples use nullable reference types, but only the WhenNotNull example requires it.

Use the property pattern to replace IsNullorEmpty

Consider adopting the new property pattern, wherever you use IsNullOrEmpty.

string? hello = "hello world";

richlander

Installing .NET Core on Linux ARM64

The following intructions can be used to install .NET Core on Linux ARM64.

Pro tip: Check out .NET Core Docker files to determine the exact instructions for installing .NET Core builds, for example .NET Core 3.1 ARM32 SDK Dockerfile.

Installing .NET Core Globally

The following instructions install the latest .NET Core globally. It isn't required to do that, but it provides the best experience.

richlander

FROM microsoft/dotnet-framework:4.7.2-sdk AS build
WORKDIR /app

# copy csproj and restore as distinct layers
COPY *.sln .
COPY aspnetapp/*.csproj ./aspnetapp/
COPY aspnetapp/*.config ./aspnetapp/
RUN nuget restore

# copy everything else and build app

richlander

.NET 5.0 Examples

The following are examples of various features.

• Modernizing a codebase for C# 9
• Top-level programs
• Various patterns of patterns
• Should rich go to the doctor
• Various patterns of records
• Records vs Classes (with init)

richlander

FROM alpine

ARG TARGETPLATFORM
ARG TARGETOS
ARG TARGETARCH
ARG TARGETVARIANT
ARG BUILDPLATFORM
ARG BUILDOS
ARG BUILDARCH
ARG BUILDVARIANT

richlander

using System;
using System.Net.Http;
using System.Net.Http.Json;

string serviceURL = "https://localhost:5001/WeatherForecast";
HttpClient client = new();
Forecast[] forecasts = await client.GetFromJsonAsync<Forecast[]>(serviceURL);

foreach(Forecast forecast in forecasts)
{

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<ProjectSdk="Microsoft.NET.Sdk.WindowsDesktop">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>netcoreapp3.0</TargetFramework>
    <UseWindowsForms>true</UseWindowsForms>
  </PropertyGroup>
</Project>

richlander

.NET Container images: whoami

We have had two relevant practices for the container images we publish:

• Don't change the user.
• Don't add users.

You can see that with our .NET 7 container images.

richlander

Inspect MCR Registry Tags for .NET Core

This workflow explores the 3.0 manifest-based tag in the mcr.microsoft.com/v2/dotnet/core/runtime repo on MCR as an example. It uses curl to call a set of container registry APIs to find image digests, layer digests, and layer location. This example is intended to show the separation between MCR as a image manifest service and Azure CDN as an image layer service.

This pattern can be used on any operating system, but the specific commands are OS-specific. curl is included in the latest versions of Windows and is also in most Linux and macOS distributions. findstr is part of Windows, however, grep can be used on Linux or macOS instead.

Inspect Manifest tag

The 3.0 tag is a manifest tag. It represents a set of potential candidate images, for various operating systems and operating systems versions. When a manifest tag is pulled by a docker client, the client picks the best image for the host op

richlander

Updating .NET Linux Build

.NET Core started out life as a cross-platform project. We naturally wanted to encourage usage on Linux. Across the first couple versions, we figured out how to build a single set of binaries that worked everywhere (e.g. for Linux x64). A key design point of that project was building on an old Linux so that our choice of build OS didn’t unnecessarily limit where .NET apps could be run. That has worked well, using CentOS 7, but it will soon go out of support. There isn't an obvious replacement for CentOS 7, requiring us to adopt a new approach.

We intend to use a combination of Mariner and a streamlined copy of Ubuntu going forward.

Breadth Targeting

The primary aspect of breadth targeting on Linux is linking with the C standard library (libc). Native code (like the .NET runtime) is compiled with a given libc and then is only able to run on distros with a libc version at le