devcontainer.json for VScode using existing Container

How to use existing container in VSCode?

I have a file called .devcontainer.json. The path is /home/myname/Documents/ABC/.devcontainer.

{
    "name": "Kaggle Dev CPU",
    "image": "gcr.io/kaggle-images/python:v100",
    "extensions": [
        "ms-python.python",
    ],
    "settings": {
        "terminal.integrated.shell.linux": "/bin/bash",
        "python.pythonPath": "/opt/conda/bin/python"
    },
    "devPort": 8888,
    "shutdownAction": "none"
}

It ran without any problem. I can access all python + other library that mimic kaggle environment. I also install some library in that container.

docker ps
>> 
CONTAINER ID   IMAGE                              COMMAND                  CREATED         STATUS          PORTS      NAMES
bd7d3c11bedc   gcr.io/kaggle-images/python:v100   "/bin/sh -c 'echo Co…"   10 months ago   Up 49 minutes   8080/tcp   affectionate_cray

Now, I want /home/myname/Documents/BCD/ ran from previous container. But how to do that?

What I have done and fails..
First attempt, Create .devcontainer.json in BCD/.devcontainer folder

{
    "name": "Kaggle Dev CPU",
    "container": "bd7d3c11bedc", 
    "extensions": [
        "ms-python.python",
    ],
    "settings": {
        "terminal.integrated.shell.linux": "/bin/bash",
        "python.pythonPath": "/opt/conda/bin/python"
    },
    "devPort": 8888,
    "shutdownAction": "none"
}

second attempt :

{
  "workspaceFolder": "/home/myname/Documents/BCD",
  "settings": {
        "terminal.integrated.shell.linux": "/bin/bash",
        "python.pythonPath": "/opt/conda/bin/python"
  },
  "extensions": [
        "ms-python.python",
  ],
  "forwardPorts": 8889,
  "remoteUser": "vscode",
  "remoteEnv": { "MY_VARIABLE": "some-value" }
}

My reference, but I got confuse with that explanation
https://code.visualstudio.com/docs/remote/attach-container
https://code.visualstudio.com/docs/remote/create-dev-container