Vertical rulers in Visual Studio Code

In addition to global "editor.rulers" setting, it's also possible to set this on a per-language level.

For example, style guides for Python projects often specify either 79 or 120 characters vs. Git commit messages should be no longer than 50 characters.

So in your settings.json, you'd put:

"[git-commit]": {"editor.rulers": [50]},
"[python]": {
    "editor.rulers": [
        79,
        120
    ]
}

Visual Studio Code 0.10.10 introduced this feature. To configure it, go to menu File → Preferences → Settings and add this to to your user or workspace settings:

"editor.rulers": [80,120]

The color of the rulers can be customized like this:

"workbench.colorCustomizations": {
    "editorRuler.foreground": "#ff4081"
}