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Visual Studio Code Remote Docker Workflow

This page describes a workflow on how to build and test NCX Infra Controller (NICo) inside a remotely running docker container. The advantage of this workflow is that it requires no tools to be installed on your native Machine, but still can provide you a similar development feeling.

Prerequisites

  • Install Visual Studio Code from https://code.visualstudio.com
  • Install the Remote Development Extension Pack
  • Enable the code command for MacBook:
    • Open VS Code
    • Press Cmd + Shift + P to open the Command Palette.
    • Type Shell Command: Install 'code' command in PATH and select it. This sets up the code command for your terminal.
  • On the remote server, update the SSH daemon configuration to support port forwarding:
    • Edit the sshd configuration file: 
      doas vi /etc/ssh/sshd_config
    • Add or update the following lines: 
      AllowTcpForwarding yes
GatewayPorts yes
    • Restart sshd daemon: 
      doas systemctl restart sshd
    • For MacBook:
      • Port forwarding may fail initially.
      • To resolve this issue, remove the ~/.ssh/known_hosts file. Source: Stack Overflow
      • Note: Be sure to back up the file before deleting it.

Basic remote setup

Start VS Code using the code command in the same shell after running nvinit:

Click the remote button on the lower left of the IDE window: . Select "Connect to Host", choose the remote hostname define in Prerequisites, and connect. A new Visual Studio Code window should open, which is now on that host. Inside that window, open the folder which contains the NICo project.

Assuming that remote machine already has all dev tools installed, and you want to work directly on the machine instead of inside a container, you could open up Visual Studio Code's integrated terminal, and for example run:

cd api
cargo test

Remote Rust Analyzer support

In order to get proper IDE support also while working on the remote host, you can install the "Rust Analyzer" extension on the remote host. To do so:

  • Open the extensions tab
  • Look for the second column in it, which is labeled: SSH: $hostname - Installed.
  • Click the download button next to it.
  • Select Rust Analyzer, and all other extensions you want to install on the remote Host. Other recommended extensions are CodeLLDB for debugging Rust code, Better TOML for editing .toml files, and GitLens.

Remote container setup

On top of developing on a remote host, one can develop inside a container that contains all dev tools. The container can either run locally (if you work on a Linux machine), or on a remote Linux machine.

To work inside the remote container, the following steps are performed:

  • Inside the NICo directory on the Linux host you are working on, place a .devcontainer/devcontainer.json file with the following details 
    // For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
// https://github.com/microsoft/vscode-dev-containers/tree/v0.245.2/containers/docker-existing-dockerfile
{
    "name": "Existing Dockerfile",

    // Sets the run context to one level up instead of the .devcontainer folder.
    "context": "../dev/docker/",

    // Update the 'dockerFile' property if you aren't using the standard 'Dockerfile' filename.
    // "dockerFile": "../Dockerfile",
    "dockerFile": "../dev/docker/Dockerfile.build-container-x86_64",

    // Use 'forwardPorts' to make a list of ports inside the container available locally.
    // "forwardPorts": [],

    // Uncomment the next line to run commands after the container is created - for example installing curl.
    // "postCreateCommand": "apt-get update && apt-get install -y curl",

    // Uncomment when using a ptrace-based debugger like C++, Go, and Rust
    "runArgs": [ "--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined" ],

    // Uncomment to use the Docker CLI from inside the container. See https://aka.ms/vscode-remote/samples/docker-from-docker.
    "mounts": [ "source=/var/run/docker.sock,target=/var/run/docker.sock,type=bind" ]

    // Uncomment to connect as a non-root user if you've added one. See https://aka.ms/vscode-remote/containers/non-root.
    //"remoteUser": "youralias"
}
    This will automatically instruct the remote container extension to pick the specified container image. The build container image is picked here, because it contains all necessary tools.
  1. Click the remote button on the lower left of the IDE window: . Select "Reopen in Container". Since a container configuration file for the project exists, Visual Studio Code should automatically build the specified Dockerfile, launch it as a container, install a VsCode remote server in it, and launch your editor window in it.
  2. The new editor window runs inside the container, and should show something along "Dev Container: Existing Dockerfile" on the lower left.
  3. You can again open an integrated terminal here, and build the project.
  4. The dev container again has a separate set of installed extensions. You will need to reinstall all extensions you need there - e.g. Rust Analyzer.

Enabling postgres inside the dev container

While the last step will you allow to build the project and run some unit-tests, all unit-tests which require a database will. To fix this, start the postgres server inside the development container:

  1. Open another internal terminal tab
  2. Start postgres: 
    /etc/init.d/postgresql start
  3. Create the user: 
    su postgres -c "/usr/lib/postgresql/15/bin/createuser -d root"
  4. Set permissions: 
    sudo -u postgres psql -c "ALTER USER root WITH SUPERUSER;"
  5. Create a database: 
    createdb root
  6. Set the DATABASE_URL environment variable: 
    export DATABASE_URL="postgresql://%2Fvar%2Frun%2Fpostgresql"

With those steps completed, running cargo test should succeed.

If you also want to run or debug unit-test from within Visual Studio code using the inline buttons "Run Test" and "Debug" that Rust-Analyzer adds, you have to add the following configuration to the Visual Studio Code json config file:

"rust-analyzer.runnableEnv": {
    "DATABASE_URL": "postgresql://%2Fvar%2Frun%2Fpostgresql"
}

Gotchas

  • If you work as root inside the dev container, editing files might make them owned by root, which can prevent working on them from your regular desktop. You might need to reset ownership when going back to your regular environment: 
    sudio chown -R yourAlias carbide/*
  • The same applies for using git inside the container as root. It will make files in .git be owned by root

Those problems might be avoidable by being able to set remoteUser in devcontainer.json to ones alias. However when doing that I wasn't able to build the devcontainer image anymore, since it is missing my user alias in /etc/passwd.

References