Getting Started with containers for .NET

Building, shipping and running .NET apps in containers

Alistair Chapman

@agc93

.NET
For
Hipsters

Alistair Chapman

@agc93

Who am I?

Alistair Chapman

agc93

.NET MVP

Information Security Architect @ Red Hat

Walking, talking case of impostor syndrome

Docker

Container technology with process and environment isolation

Works on Linux, Windows (mostly) and macOS (sort of)

.NET Core

The next generation of the .NET platform across every platform

Works on Windows, macOS (mostly) and Linux (sort of)

Working with Docker

The Essentials

Containers!
Images!
Buzzwords!

Building with Docker

Docker can also be used interactively
Creates isolated, disposable environments
Perfect for builds, packaging and cross-platform testing

Adding Docker to the Mix

Use a Dockerfile to build an image
You can then run your image to run your app in a container
Your base image decides the environment

FROM microsoft/dotnet:2.0-sdk

COPY . /app

WORKDIR /app

RUN ["dotnet", "restore"]

RUN ["dotnet", "build"]

EXPOSE 5000/tcp

ENV ASPNETCORE_URLS="http://*:5000"

CMD ["dotnet", "run"]

FROM microsoft/dotnet:2.0-sdk AS build-env

COPY . /app
WORKDIR /app
RUN dotnet restore
RUN dotnet publish -c Release -o out

FROM microsoft/dotnet:2.0-runtime

WORKDIR /app
COPY --from=build-env /app/out .

EXPOSE 5000/tcp
ENV ASPNETCORE_URLS="http://*:5000"
CMD ["dotnet", "demo.dll"]

Adding Docker to the Mix

Newer Docker versions add multi-stage build support

FROM microsoft/dotnet:2.0-sdk AS build-env
WORKDIR /app

# copy csproj and restore as distinct layers
COPY *.csproj ./
RUN dotnet restore

# copy everything else and build
COPY . ./
RUN dotnet publish -c Release -o out

# build runtime image
FROM microsoft/dotnet:2.0-runtime 
WORKDIR /app
COPY --from=build-env /app/out ./
ENTRYPOINT ["dotnet", "dotnetapp.dll"]

FROM microsoft/dotnet:2.0-sdk AS build-env
WORKDIR /app

# copy csproj and restore as distinct layers
COPY *.csproj ./
RUN dotnet restore

# copy everything else and build
COPY . ./
RUN dotnet publish -c Release -r linux-x64 -o out

# build runtime image
FROM fedora:26
WORKDIR /app
RUN dnf install -y libicu libunwind
COPY --from=build-env /app/out ./
ENTRYPOINT ["./dotnetapp"]

Building with Docker

You can use containers to:

Bootstrap
Build
Package
Test
Deploy

Publishing Docker Images

Building FOR Docker

Doing What The Cool Kids Do

Building Cloud-Native Apps in Containers

Building FOR Docker

Requires a new approach to architecture
- Loose coupling
- Isolation and autonomy
- Stateless
- Discovery and composability
Best gains from apps designed as "cloud-native"
Extremely well-suited to microservices