ASP.NET docker-compose app not coming up on assigned PORT

Question

working my way through tutorials on dockerized the API WeatherForecast web template from ASP.NET core:

1. https://code.visualstudio.com/docs/containers/quickstart-aspnet-core
2. https://code.visualstudio.com/docs/containers/docker-compose

I had to start from here, because I wasn't getting a new image to build using the tutorial here: https://docs.docker.com/compose/aspnet-mssql-compose/

"1" works, which is great. However, "2" will not work on the localhost:5000/WeatherForecast port as advertised, and I'm having some trouble debugging why after many reviews of the available docs.

I should make a note that in creating the templated app from the command line, I did choose the --no-https option.

I then used docker ps to bring up the PORTS. The web app is using 5000/tcp, 0.0.0.0:32779->80/tcp . When I substitute 5000 for 32779 , I get the API string returned instead. I know I'm missing something within docker-compose and could use some extra eyes on it. Thank you!

EDIT: For reference, the files below were generated by my VSCode editor. 1. I ran dotnet new webapi --no-https 2. I then brought up the VSCode "command pallete" and ran Docker: Add Dockerfiles to Workspace and selected 'yes' for the inclusion of docker-compose.yml file and Linux. I also choose to use port 5000 . I use Fedora 30. 4. I run dotnet build from the project root in the terminal. 5. If I run from docker commands and make the ports explicit it will work as advertised, but if I run docker-compose -f <yml-file> up -d- --build , it will not.

I just re-read this and find it annoying that I'm stuck within VSCode to fix the issue (according to the docs)

By default Docker will assign a randomly chosen host port to a port exposed by a container (the container port). In this case the exposed (container) port is 5000, but it will be exposed on the host via a random port, such as 32737.

You can use specific port on the host by changing the Docker run options used by docker-run: debug task (defined in.vscode/tasks.json file). For example, if you want to use the same port (5000) to expose the service, the docker-run: debug task definition would look like this:

a. Dockerfile

    # Please refer https://aka.ms/HTTPSinContainer on how to setup an 
    https developer certificate for your ASP .NET Core service.
    version: '3.4'

    services:
      aspdotnetdocker2:
        image: aspdotnetdocker2
        build:
          context: .
          dockerfile: Dockerfile
        ports:
          - 5000

b. docker-compose.yml

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS base
WORKDIR /app
EXPOSE 5000

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /src
COPY ["aspdotnet_docker2.csproj", "./"]
RUN dotnet restore "./aspdotnet_docker2.csproj"
COPY . .
WORKDIR "/src/."
RUN dotnet build "aspdotnet_docker2.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "aspdotnet_docker2.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "aspdotnet_docker2.dll"]

Answer 1

Have a look at docker-compose docs :

SHORT SYNTAX

Either specify both ports (HOST:CONTAINER), or just the container port (an ephemeral host port is chosen).

So try:

ports:
  - "5000:<port in ASPNETCORE_URLS>"

  # e.g.
  # - "5000:80"
  # - "44388:443"