node.js - .NET Core Docker Image for SPA Applications

Question

What is the correct Docker image to use when creating a new ASP.NET Core MVC app, specifically with the React/Redux (or other Node.js required) template? If not a specific image, what commands or process should be followed in the Dockerfile for a Node.js app backed by ASP.NET Core MVC?

I don't require the SDK version of the framework for anything other than running the backing MVC site.

dotnet new reactredux

The runtime image does not have Node.js installed, and will error when trying to run the container.

Dockerfile:

FROM microsoft/aspnetcore:latest

ARG source=./bin/Debug/netcoreapp2.0/publish/
WORKDIR /app
COPY $source .

EXPOSE 80
ENTRYPOINT ["dotnet", "Project.dll"]

Error:

Unhandled Exception: System.AggregateException: One or more errors occurred. (Failed to start Node process. To resolve this:.

[1] Ensure that Node.js is installed and can be found in one of the PATH directories.
    Current PATH enviroment variable is: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    Make sure the Node executable is in one of those directories, or update your PATH.

The project I am working with is being upgraded from ASP.NET MVC for .NET Standard 1.1 (standalone), to a new .NET Standard 2.0 React/Redux project.

Answer 1

The problem is that the base image in your dockerfile (microsoft/aspnetcore:latest) does not have node installed.

So you have to install node so you can run the project. This is the dockerfile I came up with:

FROM microsoft/aspnetcore:2.0
ARG source
EXPOSE 80 5102
ENV ASPNETCORE_URLS http://*:80
RUN apt-get -qq update && apt-get -qqy --no-install-recommends install wget gnupg 
    git 
    unzip

RUN curl -sL https://deb.nodesource.com/setup_6.x |  bash -
RUN apt-get install -y nodejs
WORKDIR /app
COPY ${source:-obj/Docker/publish} .
ENTRYPOINT ["dotnet", "Project.dll"]

Notice how on line 5 of the dockerfile I'm running a command to update apt-get. And then in line 8-9 node is installed to the docker image

There is still a problem, hot module replacement from webpack does not work. Not even a full refresh works. I'm still looking in to it.

UPDATE: so I looked into the hot module replacement problem, and it appears to be a limitation of docker for windows.

The workaround is to configure webpack so it can tell the browser to poll for changes on a determined amount of time. See this link to see how to configure it

UPDATE: Doing a little more research I found out that microsoft has an image you can use to build your project, it is called: microsoft/aspnetcore-build. This image has all the dependencies you need for building (including nodejs).

So at the end, what I did was leave my Dockerfile as it was (with microsoft/aspnetcore:2.0 as base image), and created a new Dockerfile for development which references the build image I mentioned before. With the help of docker compose I switch Dockerfiles depending on the environment.

This approach seems more convenient because when images are deployed to production environment they should have all its javascript code ready (in the case of a spa application with angular 2, react, etc), in other words they should not have a nodejs dependency, making them less heavy in size.