catstodon/.devcontainer/devcontainer.json

{
  "name": "Mastodon",
  "dockerComposeFile": "docker-compose.yml",
  "service": "app",
  "workspaceFolder": "/workspaces/mastodon",

  // Set *default* container specific settings.json values on container create.
  "settings": {},

  // Add the IDs of extensions you want installed when the container is created.
  "extensions": [
    "EditorConfig.EditorConfig",
    "dbaeumer.vscode-eslint",
    "rebornix.Ruby",
    "webben.browserslist"
  ],

  // Use 'forwardPorts' to make a list of ports inside the container available locally.
  // This can be used to network with other containers or the host.
  "forwardPorts": [3000, 4000],

  // Use 'postCreateCommand' to run commands after the container is created.
  "postCreateCommand": "bundle install --path vendor/bundle && yarn install && ./bin/rails db:setup",

  // Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
  "remoteUser": "vscode"
}