ASP.NET Core run angular build before docker build

Question

We have a basic Docker file which need to build our ASP.NET Core application. Our frontend is an Angular2 one.

In our current process we do:

• npm run build: build the angular2 frontend part, which write output JS files in /wwwroot. These files will be included by ASP.NET Core views and controllers.
• Then we docker build which build and encapsulate our ASP.NET Core project. We then intend to deploy it anywhere.

Our DockerFile:

FROM microsoft/dotnet:latest
COPY . /app
WORKDIR /app

RUN ["dotnet", "restore"]
RUN ["dotnet", "build"]

EXPOSE 5000/tcp
ENV ASPNETCORE_URLS http://*:5000

ENTRYPOINT ["dotnet", "run"]

Our question

How to add in our dockerfiles steps to:

• Run npm install required files for our Angular2 frontend. Our package.json file is at ASP.NET project root.
• Run npm run build:prod: which build Angular2 project and generated files in wwwroot.

Before running dotnet build. We tried to simply try to indicate these commands before RUN ["dotnet", "build"] :

RUN npm install
RUN npm install -g angular-cli
RUN npm run build:prod

but Azure returns an "unexpected Error" without more details.

Answer 1

Its not possible to run npm commands directly from the docker file, the docker engine needs a program like a shell or powershell to execute npm commands. That is the reason the coomand RUN npm install in the docker file does not work.

You can try specifying powershell to be used to run npm command

RUN powershell -NoProfile -Command RUN npm install

I suggest an alternative option as below

In the root of the solution, Create a build script build.sh with npm commands, dotnet restore, build, publish and run commands.

#!bin/bash
set -e
npm install
npm install -g angular-cli
npm run build:prod
dotnet restore
dotnet test test/WebTests/project.json
dotnet publish src/Web/project.json -c release -o $(pwd)/publish/web
dotnet run

Note: 1.The build.sh above is just a sample, add remove and edit as per your need.

2.Make sure that the file build.sh does not have windows specific line endings otherwise shell will have trouble executing it.

From the root of your solution, open your power shell prompt Now we can directly use the aspnetcore build image to run the application as below

docker run -it --rm -v "$pwd\:/sln" microsoft/aspnetcore-build:1.0.1 sh ./build.sh

The option -v "$pwd\:/sln" mounts the current directory as /sln directory in the container.

Refer to a very well written MSDN article Optimized Docker Images