chore: add start and stop commands

Add commands for start and stop together
with their logic for the netgen CLI.

Signed-off-by: Paul Wekesa <paul1tw1@gmail.com>

Cargo.toml

@@ -18,3 +18,5 @@ enum-as-inner = "0.6.1"
 ipnetwork = "0.20.0"
 rand = "0.8.5"
 clap = {version="4.5.23", features = ["default", "cargo"]}
+futures-util = "0.3.31"
+sysinfo = "0.33.1"

src/bin/netgen.rs

@@ -1,39 +1,106 @@
 #![feature(let_chains)]
 use netgen::plugins::Config;
 use netgen::topology::Topology;
+use netgen::PLUGIN_PIDS_FILE;
 use netgen::{error::Error, Result};
 
 use std::fs::File;
+use std::fs::OpenOptions;
+use std::io::BufRead;
 
-use clap::{command, Arg};
+use clap::{command, Arg, ArgMatches};
+use sysinfo::{Pid, System};
 
 #[tokio::main]
 async fn main() -> Result<()> {
-    let matches = command!("netgen")
-        .arg(
-            Arg::new("Config File")
-                .short('c')
-                .long("config")
-                .value_name("yaml-file")
-                .help("the file with plugin configs"),
+    let app_match = command!("netgen")
+        .subcommand(
+            command!("start")
+                .args(config_args())
+                .about("starts the netgen setup"),
         )
-        .arg(
-            Arg::new("Topo File")
-                .short('t')
-                .long("topo")
-                .value_name("yaml-file")
-                .help("file with the topology"),
+        .subcommand(
+            command!("stop")
+                .args(config_args())
+                .about("stops the running netgen setup"),
         )
         .get_matches();
-    let config = match matches.get_one::<String>("Config File") {
+
+    match app_match.subcommand() {
+        Some(("start", start_args)) => {
+            let mut topology = parse_config_args(start_args)?;
+
+            // If the file exists, then the topology is currently running
+            if File::open(PLUGIN_PIDS_FILE).is_ok() {
+                return Err(Error::GeneralError(String::from("topology is currently running. Consider running 'netgen stop -t my-topo.yml' before starting again")));
+            }
+
+            File::create(PLUGIN_PIDS_FILE).unwrap();
+
+            // "powers on" all the devices and sets up all the required links
+            topology.power_on().await?;
+
+            // Runs the plugins in the routers.
+            // and initiates their startup-config (if present)
+            topology.run().await?;
+        }
+        Some(("stop", stop_args)) => {
+            let mut topology = parse_config_args(stop_args)?;
+
+            // Turns off all the nodes
+            // as a result also deletes any dangling veth link
+            topology.power_off().await;
+
+            // Kills all the running plugin PIDs
+            if let Ok(file) = OpenOptions::new().read(true).open(PLUGIN_PIDS_FILE) {
+                let reader = std::io::BufReader::new(file);
+                let system = System::new_all();
+
+                for line in reader.lines() {
+                    if let Ok(line) = line
+                        && let Ok(pid) = line.parse::<u32>()
+                        && let Some(process) = system.process(Pid::from_u32(pid))
+                    {
+                        process.kill();
+                    }
+                }
+            }
+
+            // Delete the PID file.
+            let _ = std::fs::remove_file(PLUGIN_PIDS_FILE);
+        }
+        _ => {
+            // Probably "help"
+        }
+    }
+    Ok(())
+}
+
+fn config_args() -> Vec<Arg> {
+    vec![
+        Arg::new("Config File")
+            .short('c')
+            .long("config")
+            .value_name("yaml-file")
+            .help("the file with plugin configs"),
+        Arg::new("Topo File")
+            .short('t')
+            .long("topo")
+            .value_name("yaml-file")
+            .help("file with the topology"),
+    ]
+}
+
+fn parse_config_args(config_args: &ArgMatches) -> Result<Topology> {
+    let config = match config_args.get_one::<String>("Config File") {
         Some(config_file) => {
             let mut config_file = File::open(config_file).unwrap();
             Config::from_yaml_file(Some(&mut config_file))?
         }
         None => Config::from_yaml_file(None)?,
     };
 
-    let topo_file = match matches.get_one::<String>("Topo File") {
+    let topo_file = match config_args.get_one::<String>("Topo File") {
         Some(topo_file) => topo_file,
         None => {
             return Err(Error::GeneralError(String::from(
@@ -43,14 +110,6 @@ async fn main() -> Result<()> {
     };
 
     let mut topo_file = File::open(topo_file).unwrap();
-    let mut topology = Topology::from_yaml_file(&mut topo_file, config).unwrap();
-
-    // "powers on" all the devices and sets up all the required links
-    topology.power_on().await?;
-
-    // runs the plugins in the routers.
-    // and initiates their startup-config (if present)
-    topology.run().await?;
-
-    Ok(())
+    let topology = Topology::from_yaml_file(&mut topo_file, config.clone()).unwrap();
+    Ok(topology)
 }