5

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"]
bengineerdavis
  • 83
  • 1
  • 7
  • What does your *docker-compose.yml* look like? – weichch Apr 29 '20 at 02:35
  • ``` # 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 ``` – bengineerdavis Apr 29 '20 at 04:12
  • I apologize in advance, still learning how to use the code formatting on the forum. – bengineerdavis Apr 29 '20 at 04:13
  • It would be easier if you edit your question and post the yml file in question where you could use code format. I'd be particularly interested in the `ports` setup. – weichch Apr 29 '20 at 04:16
  • I just updated the post! – bengineerdavis Apr 29 '20 at 04:22
  • This post has an answer https://stackoverflow.com/questions/62482720/does-docker-compose-create-port-mappings-automatically – Oleksandr Dudnyk Apr 11 '22 at 13:32

1 Answers1

3

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"
weichch
  • 9,306
  • 1
  • 13
  • 25
  • Tried it, but I'm still not bringing up the expected JSON string. – bengineerdavis Apr 29 '20 at 04:41
  • Maybe the `Expose:` tag will work? EDIT: nevermind, Dockerfile already exposes port `5000`. – bengineerdavis Apr 29 '20 at 04:42
  • I assume you follow the referenced MS docs, so what is the value of `ASPNETCORE_URLS` in your yml file? Your application shall run on the port specified, then you need to expose the port correctly in your yml file, using "5000:". – weichch Apr 29 '20 at 04:46
  • Alright, works now. I thought I had done that originally, so thank you for the reminder. Go figure it was something fairly simple that I was doing that was throwing everything else off. Thanks for your help. – bengineerdavis Apr 29 '20 at 04:58