Run Blazor in Docker

Question

I've created my first Blazor test using Visual Studio 2019 (Preview). The repo is here. Everything works as expected when I hit the IISExpress button in VS.

However, I'd like to deploy my app to an Ubuntu/Dokku server. As a result, I've been trying to figure out how I might setup my server using Docker. Here's what I have so far in my Dockerfile:

# Latest .NET Core from https://hub.docker.com/_/microsoft-dotnet-core-sdk/ (not the nightly one)
FROM mcr.microsoft.com/dotnet/core/sdk:3.0.100-preview6-disco AS build-env
WORKDIR /app
# Copy everything and build
COPY . ./
RUN dotnet restore "./HollyTest.Server/HollyTest.Server.csproj"
RUN dotnet publish "./HollyTest.Server/HollyTest.Server.csproj" -c Release -o out

# Latest ASP.NET Core from https://hub.docker.com/_/microsoft-dotnet-core-aspnet/ (not the nightly one)
FROM mcr.microsoft.com/dotnet/core/aspnet:3.0.0-preview6-disco
ENV ASPNETCORE_URLS=http://+:5000
EXPOSE 5000
WORKDIR /app
COPY --from=build-env /app/out .
ENTRYPOINT ["dotnet", "HollyTest.Server.dll"]

The app compiles and the server runs, but everytime I hit the server I get a 404. So I've run the above commands on my local machine:

cd app
dotnet restore .\HollyTest.Server\HollyTest.Server.csproj
dotnet publish "./HollyTest.Server/HollyTest.Server.csproj" -c Release -o out
cd out
dotnet .\HollyTest.Server.dll

Then when I run curl localhost:5000 I see the following:

Hosting environment: Production
Content root path: C:\Users\hmurphy\Documents\GitHub\app\out
Now listening on: http://localhost:5000
Now listening on: https://localhost:5001
Application started. Press Ctrl+C to shut down.
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://localhost:5000/
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint 'Fallback {*path:nonfile}'
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint 'Fallback {*path:nonfile}'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished in 223.05540000000002ms 404
Application is shutting down...

In the log generated by Visual Studio, it looks healthier:

Hosting environment: Development
Content root path: C:\Users\hmurphy\Documents\GitHub\HollyTest\HollyTest.Server
Now listening on: http://localhost:50873
Application started. Press Ctrl+C to shut down.
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://localhost:50873/
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint 'Fallback {*path:nonfile}'
info: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[6]
      The file /index.html was not modified
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint 'Fallback {*path:nonfile}'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished in 326.5401ms 304 text/html
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
.
.
.

I'm assuming that I'm missing some sort of configuration/missing a step. Is it do with the "content root path"? In the ./out folder, there is no HollyTest.Server folder.

I don't have much experience with ASP.NET Core (or modern web development in .NET). Can anybody help me and point me in the right direction?

Answer 1

There well-known issue in Balzor on .NET Core Preview 6 (https://github.com/aspnet/AspNetCore/issues/11636) and (https://github.com/aspnet/AspNetCore/issues/11185)

Either you wait for Preview 7, or add to your Dockerfile

# After publish
COPY out/wwwroot/_content/hollytestclient out/wwwroot/

then run docker run -p 8081:5000 -it holly_test:latest