Asp.Net Core on Docker - asp.net

I'm currently trying to launch a Docker component with a ASP.NET Core application.
I use the following repo for my test : https://github.com/aspnet/cli-samples
I ran the following commande without any issue :
git clone https://github.com/aspnet/cli-samples aspnet-Home
cd aspnet-Home/HelloWeb
cat Dockerfile
FROM microsoft/aspnetcore
WORKDIR /app
COPY . .
ENTRYPOINT ["dotnet", "helloweb.dll"]
sudo docker build –t helloweb .
sudo docker run -d helloweb
The image is visible using the sudo docker images, but the container doesn't launch and is not visible with sudo docker ps:
And if I browse my website, obsviously I do not see data.
Is the repo not good for my test ? Is there any mistake I do on the docker container creation ?
Running the -it command give me the following output:

The error you highlighted is because helloweb.dll you set as the ENTRYPOINT doesn't exist. There could be two reasons for it
1 You didn't build the project yet
In this case you should run dotnet restore from the project home directory, then navigate to HelloWeb directory and run dotnet publish. When I run this command, I see the following:
publish: Published to /code/HelloWeb/bin/Debug/netcoreapp1.0/publish
Published 1/1 projects successfully
2 You built the project, but the ENTRYPOINT path is wrong
COPY . . directive will copy everything from the current directory into your app directory. That means HelloWeb.dll will actually be in bin/Debug/netcoreapp1.0/publish/ (or bin/Release/... for release builds).
Option 1: Modify your entrypoint with the full path
ENTRYPOINT ["dotnet", "bin/Debug/netcoreapp1.0/publish/HelloWeb.dll"]
Your application should happily start and serve requests.
Option 2: Modify your COPY directive
Once your project has been published, everything you'll need to run it will be in the publish directory. You could copy the contents of that into the /app directory and your entrypoint will be correct. That would look like this
FROM microsoft/aspnetcore
WORKDIR /app
COPY ./bin/Debug/netcoreapp1.0/publish/ .
EXPOSE 80
ENTRYPOINT ["dotnet", "HelloWeb.dll"]
You will also probably want to add the EXPOSE directive to tell Docker that your container will be listening on port 80.
When that succeeds, you should see (if you run in interactive mode)
docker run -it helloweb
Hosting environment: Production
Content root path: /app
Now listening on: http://+:80
Application started. Press Ctrl+C to shut down.
You could also use the microsoft/dotnet:latest image instead. That image comes with the SDK installed and a very convenient run command. The Dockerfile would look like this
FROM microsoft/dotnet:latest
COPY . /app
WORKDIR /app
RUN dotnet restore
ENV ASPNETCORE_URLS http://*:5000
EXPOSE 5000
ENTRYPOINT ["dotnet", "run"]
and you should be able to modify your source and build and run your container.

Related

ASP.NET Docker image exits immediately in AWS ECS

I have a dockerized ASP.NET application that I am hosting on AWS ECS. I have a task definition with one container image: the ASP.NET app, which is marked as essential. When I run that task in a service, the task provisions, is running, and then immediately changes to DEPROVISIONING (Essential container in task exited). I can run the image on my machine (with Docker Desktop) with no problem, the image listens on the specified port and doesn't exit, as expected. The issue seems to be that when I run that container on ECS, the container immediately exits.
Here is my Dockerfile, I don't see anything wrong, but I could be mistaken.
FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build-env
WORKDIR /App
# Copy everything
COPY . ./
# Restore as distinct layers
RUN dotnet restore
# Build and publish a release
RUN dotnet publish -c Release -o out
# Build runtime image
FROM mcr.microsoft.com/dotnet/aspnet:6.0
EXPOSE 80
WORKDIR /App
COPY --from=build-env /App/out .
ENTRYPOINT ["dotnet", "webapi.dll"]
I found my issue after looking at the logs like Hans Kilian was wondering.
The error I was getting was "exec /usr/bin/dotnet: exec format error". After reading This post, I discovered that the platform I was building for was specific to my machine, an m1 mac. In order to run my container on AWS Fargate, I had to build for linux amd64, using this command: docker buildx build --platform=linux/amd64 -t {app-name}:latest.

Docker errror: dotnet-file.dll does not exist

I have successfully builded my app and there is image listed my-app:2.7
But when I try to run it error says:
Any idea where is wrong?
docker run -it --rm -p 5000:80 --name my-app:2.7 uploadcore Unable to find image 'uploadcore:latest' locally docker: Error response from daemon: pull access denied for uploadcore, repository does not exist or may require 'docker login': denied: requested access to the resource is denied. See 'docker run --help'.
docker run -p 5000:80 my-app:2.7 Could not execute because the specified command or file was not found. Possible reasons for this include: You misspelled a built-in dotnet command. You intended to execute a .NET program, but dotnet-uploadcore.dll does not exist. You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.
Dockerfile:
FROM mcr.microsoft.com/dotnet/nightly/sdk:6.0 AS base
WORKDIR /app
EXPOSE 59518
EXPOSE 44364
FROM mcr.microsoft.com/dotnet/nightly/sdk:6.0 AS build
WORKDIR /src
COPY UploadCore/UploadCore.csproj UploadCore/
RUN dotnet restore UploadCore/UploadCore.csproj
COPY . .
WORKDIR /src/UploadCore
RUN dotnet build UploadCore.csproj -c Release -o /app
FROM build AS publish
RUN dotnet publish UploadCore.csproj -c Release -o /app
FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "uploadcore.dll"]
Files structure
Context
Controllers
Migrations
Models
Properties
Service
Views
wwwroot
Program.cs
Startup.cs
UploadCore.csproj
appsettings.Development.json
appsettings.json
libman.json
Linux is case sensitive, so your ENTRYPOINT has to be
ENTRYPOINT ["dotnet", "UploadCore.dll"]
Your second docker run command works. You can add a container name with the --name option like this
docker run -p 5000:80 --name mycontainer my-app:2.7
The image name has to be the first parameter that isn't an option. In your first docker run command, the first one is uploadcore, so docker looks for an image called that and it can't find it.

This site can’t be reached - Docker

I have created the Containers / Apps
But when I run it, I got this error message: This site can’t be reached. localhost unexpectedly closed the connection.
But when I run from Visual Studio, I can run it.
Extra troubleshooting steps is below
This is docker file
FROM mcr.microsoft.com/dotnet/aspnet:5.0-focal AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
# Creates a non-root user with an explicit UID and adds permission to access the /app folder
# For more info, please refer to https://aka.ms/vscode-docker-dotnet-configure-containers
RUN adduser -u 5678 --disabled-password --gecos "" appuser && chown -R appuser /app
USER appuser
FROM mcr.microsoft.com/dotnet/sdk:5.0-focal AS build
WORKDIR /src
COPY ["WebApplication3/WebApplication3.csproj", "WebApplication3/"]
RUN dotnet restore "WebApplication3/WebApplication3.csproj"
COPY . .
WORKDIR "/src/WebApplication3"
RUN dotnet build "WebApplication3.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "WebApplication3.csproj" -c Release -o /app/publish /p:UseAppHost=false
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "WebApplication3.dll"]
By default, Swagger is only available when the app runs in development mode. Docker containers, by default, don't run in development mode.
Try accessing the API directly on http://localhost:49155/WeatherForecast
You can run the container in development mode by setting the environment variable ASPNETCORE_ENVIRONMENT to Development by adding the option -e ASPNETCORE_ENVIRONMENT=Development to your docker run command. Then Swagger should be available.

How to access ASP.NET Swagger API published in Docker?

I have made an ASP.NET API with scaffolding. I have generated a docker file in Visual Studio 2019:
#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.
FROM mcr.microsoft.com/dotnet/aspnet:5.0-buster-slim AS base
WORKDIR /app
EXPOSE 80
FROM mcr.microsoft.com/dotnet/sdk:5.0-buster-slim AS build
WORKDIR /src
COPY ["CoinAPI.csproj", "CoinAPI/"]
RUN dotnet restore "CoinAPI/CoinAPI.csproj"
WORKDIR "/src/CoinAPI"
COPY . .
RUN dotnet build "CoinAPI.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "CoinAPI.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "CoinAPI.dll"]
I am building the project with command:
docker build -t coinapi .
And running it with:
docker run -dp 12344:12344 coinapi
The container is running in docker desktop in Windows, but when I access localhost:12344 I get an error 404. After adding this line of code webBuilder.UseUrls("http://localhost:12344"); in Program.cs file, I am getting an ERR_EMPTY_RESPONSE when accessing the URL. What can I do to successfully access my Swagger API run in a docker container?
The application listens to ports 80 and 443 by default, try this
docker run -dp 12344:80 coinapi
And you should access the web with http://localhost:12344
The thing that did the trick was to change webBuilder.UseUrls("http://localhost:12344"); to webBuilder.UseUrls("http://+:12344"); and now the API works and I can connect to it via the browser with http://localhost:12344/

In Docker for windows, how do i access a webapi running on my dev machine from the container i aslo have on my machine?

I am currently running docker for windows with a container using the asp.net core 2.0 image.
I also have a web api application running on iis on the development machine (the same machine i have docker installed with the container)
I need to be able to make an API request to the api on my dev machine.
I cant seem to get this to work.
Any help would be appreciated
Update:
My docker file
FROM microsoft/aspnetcore:2.0 AS base
WORKDIR /app
EXPOSE 80
FROM microsoft/aspnetcore-build:2.0 AS build
WORKDIR /src
COPY mysol.sln ./
COPY mysol.Web/mysol.Web.csproj mysol.Web/
RUN dotnet restore -nowarn:msb3202,nu1503
COPY . .
WORKDIR /src/CraOrchestrator.Web
RUN dotnet build -c Release -o /app
FROM build AS publish
RUN dotnet publish -c Release -o /app
FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "mysol.Web.dll"]
I am running the container with
docker run -dit -p 1253:80 -v c:/data:/data --name sol mysol:latest
There should not be any problem for your containerised app to reach an app running on the host or even a different container. The problem may be in the .dockerfile.
You only need the executables in your image to correctly run your application. Your .dockerfile may look like:
# use microsoft dotnet core as base image - including ASP.NET Core
FROM microsoft/dotnet:2.0.5-runtime
# set the working directory
WORKDIR /app
# copy executables
ADD . /app
# make port 5050 available - should not matter much since this is a client app
EXPOSE 5050
# run app
CMD ["dotnet", "mysol.Web.dll"]
To create the image:
docker build -t app-image .
To run the container (and so your application):
docker run --name myapp -p 4000:5050 app-image
You may not require the port setup since the application you run is the one performing requests to the Web API running in IIS.

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