ASPNETCORE_ENVIRONMENT in Docker

Question

i have problems setting the ASPNETCORE_ENVIRONMENT variable running my project in a docker container. The problem is that the value is always set/overwritten to "Development".

I have tried setting the environment variable in my Dockerfile using

ENV ASPNETCORE_ENVIRONMENT test

also tried setting the environment variable in my docker-compose file using

environment:
      - ASPNETCORE_ENVIRONMENT=test

When I set any other environment variable it works, for example:

environment:
      - OTHER_TEST_VARIABLE=test

I assume that the value for ASPNETCORE_ENVIRONMENT variable is overwritten somewhere but I have difficulties finding out where.

I have added Docker support to an existing project and am running the project directly via Visual Studio's Docker/Docker compose option

The project runs on Asp Net Core 2.1

Thanks in advance

My launchSettings.json:

{
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:53183/",
      "sslPort": 0
    }
  },
  "profiles": {

    "Docker": {
      "commandName": "Docker",
      "launchBrowser": true,
      "launchUrl": "{Scheme}://localhost:{ServicePort}/api/values"

    }

  }
}

I also tried adding the environment variable configuration to the launchSettings.json

"Docker": {
          "commandName": "Docker",
          "launchBrowser": true,
          "launchUrl": "{Scheme}://localhost:{ServicePort}/api/values",
          "environmentVariables": {
           "ASPNETCORE_ENVIRONMENT": "test"
      }
        }

My Webhost:

 public static IWebHost BuildWebHost(string[] args)
        {
           return WebHost.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration((builderContext,config) =>
                {
                    config.AddEnvironmentVariables();
                })
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.AddConsole();
                    logging.AddDebug();
                })
                .UseStartup<Startup>()
                .Build();

        }

My docker-compose.yml

version: '3.4'

services:
  api:
    image: ${DOCKER_REGISTRY}api
    build:
      context: .
      dockerfile: API/Dockerfile
    environment:
     - ASPNETCORE_ENVIRONMENT=test 

My Dockerfile:

FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base

WORKDIR /app
EXPOSE 80
FROM microsoft/dotnet:2.1-sdk AS build
WORKDIR /src
COPY API/API.csproj API/
RUN dotnet restore API/API.csproj
COPY . .
WORKDIR /src/API
RUN dotnet build API.csproj -c Release -o /app

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

FROM base AS final
WORKDIR /app
COPY --from=publish /app .


ENTRYPOINT ["dotnet", "API.dll"]

Here is a list of the environment variables in the container

C:\Users\Administrator>docker exec -ti d6 /bin/bash
root@d6f26d2ed2c3:/app# printenv
HOSTNAME=d6f26d2ed2c3
ASPNETCORE_URLS=http://+:80
test1=asdasd
test2=dasdasd
test3=dasdasd
PWD=/app
HOME=/root
NUGET_FALLBACK_PACKAGES=/root/.nuget/fallbackpackages
DOTNET_USE_POLLING_FILE_WATCHER=1
ASPNETCORE_VERSION=2.1.3
DOTNET_RUNNING_IN_CONTAINER=true
TERM=xterm
SHLVL=1
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
ASPNETCORE_ENVIRONMENT=Development
_=/usr/bin/printenv
root@d6f26d2ed2c3:/app#

Solution 1

It works for me by configuring ASPNETCORE_ENVIRONMENT with command dotnet CoreDocker.dll --environment="X"

Try to change dockerfile like below:

ENTRYPOINT ["dotnet", "CoreDocker.dll", "--environment=X"]

Solution 2

In the docker-compose.override.yml file, you should find something like that:

version: '3.4'

services:
  webapplication1:
    environment:
      - ASPNETCORE_ENVIRONMENT=Development # <==

Solution 3

Visual Studio Docker Tooling

In case you use the Docker integration for Visual Studio (debug container from within VS) you need to pay special attention to the defaults.

Default Environment Variables

When the tooling is starting the debugger with a docker run [..] command, it supplies an -e "ASPNETCORE_ENVIRONMENT=Development" argument. You can overwrite this environment variable in the Properties/launchSettings.json.

Even though I can't see it in the issued command, in my testing I experienced another default variable ASPNETCORE_URLS=http://+:80 as well.

A good starting point to read about VS Docker Tooling is this blog post and the official documentation.

.Net-Core 3.0 Generic Host

When you use the generic host in .Net-Core 3.0 you might encounter issues when you use the new generic DOTNET_ENVIRONMENT variable, since you will have two environments specified then. This can be hard to debug. So what I like to do is to unset all defaults initially and start fresh in my Properties/launchSettings.json:

{
  "$schema": "http://json.schemastore.org/launchsettings.json",
  "profiles": {
    "Docker": {
      "commandName": "Docker",
      "environmentVariables": {
        // Overwrite default VS Docker Tools environment variables first (ASPNETCORE_ENVIRONMENT=Development; ASPNETCORE_URLS=http://+:80)
        // https://www.paraesthesia.com/archive/2019/06/18/tips-on-container-tools-for-visual-studio/
        "ASPNETCORE_ENVIRONMENT": "",
        "ASPNETCORE_URLS": "",
        "DOTNET_ENVIRONMENT": "Production",
        "DOTNET_URLS": "http://+:80"
      }
    }
  }
}

Solution 4

Thanks for your comments, I solved my issue. It was just my mistake.

My problem was that when I added Docker-Support to my project I already had a Dockerfile included in the project.

When VS generated files for Docker-support, there was a second Dockerfile created, and one of the Dockerfiles was renamed to "Dockerfile.original".

I was using the "Dockerfile" visible in the solution explorer (which was somehow mapped to the "Dockerfile.original" file in the filesystem)

It seems that in the background my changes where written to "Dockerfile.original" but this file wasn't used while docker-compose was running. It used the empty generated Dockerfile that wasn't visible in the Solution explorer.

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Comments

[Lee Gary]

It worked for me when I did this too, but I looked harder and realised that I had 2 sets of environment values set, merging them into one worked fine after that

[Javid]

Saved my life just like that. yeah.