feat: bootstrap awg2 harness rust workspace and docs

traffic_core/src/swap.rs

@@ -0,0 +1,51 @@
+use std::{fs, process::Command};
+
+use crate::config::Config;
+
+pub fn ensure_swap(cfg: &Config) -> anyhow::Result<()> {
+    if !cfg.swap.enabled {
+        return Ok(());
+    }
+
+    let path = &cfg.swap.path;
+    if !std::path::Path::new(path).exists() {
+        run("fallocate", &["-l", &format!("{}M", cfg.swap.size_mb), path])?;
+        run("chmod", &["600", path])?;
+        run("mkswap", &[path])?;
+    }
+
+    let swapon = Command::new("swapon").args(["--show"]).output()?;
+    let active = String::from_utf8_lossy(&swapon.stdout);
+    if !active.contains(path) {
+        run("swapon", &["-p", &cfg.swap.priority.to_string(), path])?;
+    }
+
+    ensure_fstab(path, cfg.swap.priority)?;
+    run("sysctl", &["-w", &format!("vm.swappiness={}", cfg.swap.swappiness)])?;
+    Ok(())
+}
+
+fn ensure_fstab(path: &str, priority: i32) -> anyhow::Result<()> {
+    let file = "/etc/fstab";
+    let content = fs::read_to_string(file).unwrap_or_default();
+    if content.lines().any(|l| l.contains(path) && l.contains("swap")) {
+        return Ok(());
+    }
+    let line = format!("{path} none swap sw,pri={priority} 0 0\n");
+    fs::write(file, format!("{}{}", content, line))?;
+    Ok(())
+}
+
+fn run(program: &str, args: &[&str]) -> anyhow::Result<()> {
+    let out = Command::new(program).args(args).output()?;
+    if !out.status.success() {
+        anyhow::bail!(
+            "{} {:?} failed: {}",
+            program,
+            args,
+            String::from_utf8_lossy(&out.stderr)
+        );
+    }
+    Ok(())
+}
+