launch.json

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [

        {
            "preLaunchTask": {
                "type": "cargo",
                "subcommand": "build",
                "problemMatcher": [
                    "$rustc"
                ],
                "label": "Rust: cargo build"
            },
            "env": {"DATABASE_URL": "/tmp/olarust.db"},
            "type": "lldb",
            "request": "launch",
            "name": "Debug",
            "program": "${workspaceFolder}/target/debug/sample",
            "args": [],
            "cwd": "${workspaceFolder}",
            "sourceMap": {
                "/rustc/CHANGE_HERE/src": "CHANGE_HERE"
            }
        }
    ]
}