Question 279869 in Docker Question posted in
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.NET 6 Docker: Why I can't see env variable in Docker container?

There is the next section in launchsettings.json of the ASP.NET Core Web API project:

"Docker": {
  "commandName": "Docker",
  "launchBrowser": true,
  "launchUrl": "{Scheme}://{ServiceHost}:{ServicePort}/swagger",
  "environmentVariables": {
    "ASPNETCORE_URLS": "https://+:443;http://+:80",
    "MYSECRETS__MYDBPASSWORD": "MyPassValue"
  },
  "publishAllPorts": true,
  "useSSL": true
}

I run the app in a docker container and my application works fine taking a password from MYSECRETS__MYDBPASSWORD env variable. But when I try to printenv (as root user) inside the container, I can’t see my env var. I also tried to find it in Docker Desktop -> Inspect but without success.

In Visual Studio 2022 -> Output -> Container Tools I also can’t see that the variable is passed to the container with -e argument.

If I change the password to something wrong in launchsettings.json and re-run the container, application fails because of the wrong authentication. So, the env variable is definitely inside the container but I can’t see it.

Why I can’t see it and how it’s passed inside the container?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    It turned out that Visual Studio sets environment variables per process when run Web API project in Docker. Env vars can be seen the next way:

    # Find your dotnet process ID
ps faux
# Show env vars for your process ID (PID)
cat /proc/[PID]/environ | tr '' 'n'

    But when I run the application via docker-compose project with setting env vars in docker-compose.override.yml file, they can be seen with simple printenv command.


  2. 0

    You mentioned you are using Visual Studio, so you can use docker-compose.override.yml to Override Visual Studio’s Docker Compose configuration. This official article just support Visual Studio in Windows.
    enter image description here

    Sample: docker-compose.override.yml

    version: '3.4'

services:
  your-service-name:
    environment:
      - ASPNETCORE_URLS=https://+:443;http://+:80
      - MYSECRETS__MYDBPASSWORD=MyPassValue

    And if you deploy it to docker, you could use below command.

    docker run -e ASPNETCORE_URLS="https://+:443;http://+:80" -e MYSECRETS__MYDBPASSWORD=MyPassValue your-image-name
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