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How do I build with docker?

Using Docker makes it possible to deploy your application as a docker container or release an image on docker hub. This recipe walks you through creating a Dockerfile and automating the build and test process with Docker Hub.

1. Create a .dockerignore file

Create a .dockerignore file with the same contents as .gitignore

Linux
cp .gitignore .dockerignore
Windows
copy .gitignore .dockerignore

Now, add the following lines to the .dockerignore file:

.git

2. Create the dockerfile

Create a Dockerfile with the following contents:

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build

# Install node
ARG NODE_MAJOR=20
RUN apt-get update
RUN apt-get install -y ca-certificates curl gnupg
RUN mkdir -p /etc/apt/keyrings
RUN curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg
RUN echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_$NODE_MAJOR.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list
RUN apt-get update && apt-get install nodejs -y

WORKDIR /workspace
COPY . .
RUN dotnet tool restore
RUN dotnet run Bundle

FROM mcr.microsoft.com/dotnet/aspnet:8.0-alpine
COPY --from=build /workspace/deploy /app
WORKDIR /app
EXPOSE 5000
ENTRYPOINT [ "dotnet", "Server.dll" ]

This uses multistage builds to keep the final image small.

3. Building and running with docker locally

  1. Build the image docker build -t my-safe-app .
  2. Run the container docker run -it -p 8080:8080 my-safe-app
  3. Open the page in browser at http://localhost:8080

Because the build is done entirely in docker, Docker Hub automated builds can be setup to automatically build and push the docker image.

4. Testing the server

Create a docker-compose.server.test.yml file with the following contents:

version: '3.4'
services:
    sut:
        build:
            target: build
            context: .
        working_dir: /workspace/tests/Server
        command: dotnet run
To run the tests execute the command docker-compose -f docker-compose.server.test.yml up --build

The template is not currently setup for automating the client tests in ci.

Docker Hub can also run automated tests for you.

Follow the instructions to enable Autotest on docker hub.

5. Making the docker build faster

Not recommended for most applications

If you often build with docker locally, you may wish to make the build faster by optimising the Dockerfile for caching. For example, it is not necessary to download all paket and npm dependencies on every build unless there have been changes to the dependencies.

Furthermore, the client and server can be built in separate build stages so that they are cached independently. Enable Docker BuildKit to build them concurrently.

This comes at the expense of making the dockerfile more complex; if any changes are made to the build such as adding new projects or migrating package managers, the dockerfile must be updated accordingly.

The following should be a good starting point but is not guaranteed to work.

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build

# Install node
ARG NODE_MAJOR=20
RUN apt-get update
RUN apt-get install -y ca-certificates curl gnupg
RUN mkdir -p /etc/apt/keyrings
RUN curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg
RUN echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_$NODE_MAJOR.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list
RUN apt-get update && apt-get install nodejs -y

WORKDIR /workspace
COPY .config .config
RUN dotnet tool restore
COPY .paket .paket
COPY paket.dependencies paket.lock ./

FROM build as server-build
COPY src/Shared src/Shared
COPY src/Server src/Server
RUN cd src/Server && dotnet publish -c release -o ../../deploy

FROM build as client-build
COPY package.json package-lock.json ./
RUN npm install
COPY src/Shared src/Shared
COPY src/Client src/Client
# tailwind.config.js needs to be in the dir where the
# vite build command is run from otherwise styles will
# be missing from the bundle
COPY src/Client/tailwind.config.js .
RUN dotnet fable src/Client -o src/Client/output --run npx vite build src/Client

FROM mcr.microsoft.com/dotnet/aspnet:8.0-alpine
COPY --from=server-build /workspace/deploy /app
COPY --from=client-build /workspace/deploy /app
WORKDIR /app
EXPOSE 5000
ENTRYPOINT [ "dotnet", "Server.dll" ]