feat: add periodic backups thread

.cargo/config.toml

@@ -0,0 +1,2 @@
+[alias]
+runs = "run -- paper 1.19.4-545 --config data/config --backup data/backups --world data/worlds data/paper-1.19.4-545.jar"

src/main.rs

@@ -1,9 +1,10 @@
 mod server;
 
-use clap::{Parser, Subcommand};
-use server::{ServerCommand, ServerType};
+use clap::Parser;
+use server::ServerType;
 use std::io;
 use std::path::PathBuf;
+use std::sync::{Arc, Mutex};
 
 #[derive(Parser)]
 #[command(author, version, about, long_about = None)]
@@ -15,43 +16,61 @@ struct Cli {
     /// Server jar to execute
     jar: PathBuf,
 
-    /// Directory where configs are stored, and where the server will run; defaults to the current
-    /// directory.
+    /// Directory where configs are stored, and where the server will run [default: .]
     #[arg(long, value_name = "CONFIG_DIR")]
     config: Option<PathBuf>,
-    /// Directory where world files will be saved; defaults to ../worlds
+    /// Directory where world files will be saved [default: ../worlds]
     #[arg(long, value_name = "WORLD_DIR")]
     world: Option<PathBuf>,
-    /// Directory where backups will be stored; defaults to ../backups
+    /// Directory where backups will be stored [default: ../backups]
     #[arg(long, value_name = "BACKUP_DIR")]
     backup: Option<PathBuf>,
+    /// Java command to run the server jar with
+    #[arg(long, value_name = "JAVA_CMD", default_value_t = String::from("java"))]
+    java: String,
 
-    /// XMS value for the server instance
-    #[arg(long)]
-    xms: Option<u32>,
-    /// XMX value for the server instance
-    #[arg(long)]
-    xmx: Option<u32>,
+    /// XMS value in megabytes for the server instance
+    #[arg(long, default_value_t = 1024)]
+    xms: u64,
+    /// XMX value in megabytes for the server instance
+    #[arg(long, default_value_t = 2048)]
+    xmx: u64,
+
+    /// How many backups to keep
+    #[arg(short = 'n', long, default_value_t = 7)]
+    max_backups: u64,
+    /// How frequently to perform a backup, in minutes
+    #[arg(short = 't', long, default_value_t = 720)]
+    frequency: u64,
+}
+
+fn backups_thread(counter: Arc<Mutex<server::ServerProcess>>, frequency: u64) {
+    loop {
+        std::thread::sleep(std::time::Duration::from_secs(frequency * 60));
+
+        {
+            let mut server = counter.lock().unwrap();
+            server.backup();
+        }
+    }
 }
 
 fn main() {
     let cli = Cli::parse();
 
-    let mut cmd = server::ServerCommand::new(cli.type_, &cli.server_version)
+    let cmd = server::ServerCommand::new(cli.type_, &cli.server_version)
+        .java(&cli.java)
         .jar(cli.jar)
         .config(cli.config.unwrap_or(".".into()))
         .world(cli.world.unwrap_or("../worlds".into()))
-        .backup(cli.backup.unwrap_or("../backups".into()));
+        .backup(cli.backup.unwrap_or("../backups".into()))
+        .xms(cli.xms)
+        .xmx(cli.xmx)
+        .max_backups(cli.max_backups);
+    let counter = Arc::new(Mutex::new(cmd.spawn().expect("Failed to start server.")));
 
-    if let Some(xms) = cli.xms {
-        cmd = cmd.xms(xms);
-    }
-
-    if let Some(xmx) = cli.xmx {
-        cmd = cmd.xmx(xmx);
-    }
-
-    let mut server = cmd.spawn().expect("Failed to start server.");
+    let clone = Arc::clone(&counter);
+    std::thread::spawn(move || backups_thread(clone, cli.frequency));
 
     let stdin = io::stdin();
     let input = &mut String::new();
@@ -59,10 +78,12 @@ fn main() {
     loop {
         input.clear();
         stdin.read_line(input);
-        println!("input: {}", input.trim());
-        if let Err(e) = server.send_command(input) {
-            println!("{}", e);
-        };
+        {
+            let mut server = counter.lock().unwrap();
+            if let Err(e) = server.send_command(input) {
+                println!("{}", e);
+            };
+        }
 
         if input.trim() == "stop" {
             break;

src/server/command.rs

@@ -4,7 +4,7 @@ use std::fmt;
 use std::fs::File;
 use std::io::Write;
 use std::path::{Path, PathBuf};
-use std::process::{Child, Command, Stdio};
+use std::process::{Command, Stdio};
 
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, ValueEnum)]
 pub enum ServerType {
@@ -33,8 +33,9 @@ pub struct ServerCommand {
     config_dir: PathBuf,
     world_dir: PathBuf,
     backup_dir: PathBuf,
-    xms: u32,
-    xmx: u32,
+    xms: u64,
+    xmx: u64,
+    max_backups: u64,
 }
 
 impl ServerCommand {
@@ -49,6 +50,7 @@ impl ServerCommand {
             backup_dir: PathBuf::from("backups"),
             xms: 1024,
             xmx: 2048,
+            max_backups: 7,
         }
     }
 
@@ -79,21 +81,26 @@ impl ServerCommand {
         self
     }
 
-    pub fn xms(mut self, v: u32) -> Self {
+    pub fn xms(mut self, v: u64) -> Self {
         self.xms = v;
         self
     }
 
-    pub fn xmx(mut self, v: u32) -> Self {
+    pub fn xmx(mut self, v: u64) -> Self {
         self.xmx = v;
         self
     }
 
+    pub fn max_backups(mut self, v: u64) -> Self {
+        self.max_backups = v;
+        self
+    }
+
     fn accept_eula(&self) -> std::io::Result<()> {
         let mut eula_path = self.config_dir.clone();
         eula_path.push("eula.txt");
         let mut eula_file = File::create(eula_path)?;
-        eula_file.write(b"eula=true")?;
+        eula_file.write_all(b"eula=true")?;
 
         Ok(())
     }
@@ -123,6 +130,7 @@ impl ServerCommand {
             config_dir,
             world_dir,
             backup_dir,
+            self.max_backups,
             child,
         ))
     }

src/server/process.rs

@@ -1,12 +1,15 @@
 use crate::server::ServerType;
 use flate2::write::GzEncoder;
 use flate2::Compression;
-use std::fs::File;
-use std::io;
 use std::io::Write;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 use std::process::Child;
-use std::process::{Command, Stdio};
+
+#[link(name = "c")]
+extern "C" {
+    fn geteuid() -> u32;
+    fn getegid() -> u32;
+}
 
 pub struct ServerProcess {
     type_: ServerType,
@@ -14,6 +17,7 @@ pub struct ServerProcess {
     config_dir: PathBuf,
     world_dir: PathBuf,
     backup_dir: PathBuf,
+    max_backups: u64,
     child: Child,
 }
 
@@ -24,6 +28,7 @@ impl ServerProcess {
         config_dir: PathBuf,
         world_dir: PathBuf,
         backup_dir: PathBuf,
+        max_backups: u64,
         child: Child,
     ) -> ServerProcess {
         ServerProcess {
@@ -32,6 +37,7 @@ impl ServerProcess {
             config_dir,
             world_dir,
             backup_dir,
+            max_backups,
             child,
         }
     }
@@ -61,17 +67,41 @@ impl ServerProcess {
         Ok(())
     }
 
+    /// Perform a backup by disabling the server's save feature and flushing its data, before
+    /// creating an archive file.
     pub fn backup(&mut self) -> std::io::Result<()> {
+        self.custom("say backing up server")?;
+
         // Make sure the server isn't modifying the files during the backup
         self.custom("save-off")?;
         self.custom("save-all")?;
 
+        // TODO implement a better mechanism
+        // We wait some time to (hopefully) ensure the save-all call has completed
+        std::thread::sleep(std::time::Duration::from_secs(10));
+
+        let res = self.create_backup_archive();
+
+        if res.is_ok() {
+            self.remove_old_backups()?;
+        }
+
+        // The server's save feature needs to be enabled again even if the archive failed to create
+        self.custom("save-on")?;
+
+        self.custom("say server backed up successfully")?;
+
+        res
+    }
+
+    /// Create a new compressed backup archive of the server's data.
+    fn create_backup_archive(&mut self) -> std::io::Result<()> {
         // Create a gzip-compressed tarball of the worlds folder
         let filename = format!(
             "{}",
             chrono::offset::Local::now().format("%Y-%m-%d_%H-%M-%S.tar.gz")
         );
-        let path = self.backup_dir.join(&filename);
+        let path = self.backup_dir.join(filename);
         let tar_gz = std::fs::File::create(path)?;
         let enc = GzEncoder::new(tar_gz, Compression::default());
         let mut tar = tar::Builder::new(enc);
@@ -87,15 +117,43 @@ impl ServerProcess {
         // We add a file to the backup describing for what version it was made
         let info = format!("{} {}", self.type_, self.version);
         let info_bytes = info.as_bytes();
+
         let mut header = tar::Header::new_gnu();
         header.set_size(info_bytes.len().try_into().unwrap());
+        header.set_mode(0o100644);
+        unsafe {
+            header.set_gid(getegid().into());
+            header.set_uid(geteuid().into());
+        }
 
         tar.append_data(&mut header, "info.txt", info_bytes)?;
 
         // tar.append_dir_all("config", &self.config_dir)?;
-        //
+
         // Backup file gets finalized in the drop
 
-        self.custom("save-on")
+        Ok(())
+    }
+
+    /// Remove the oldest backups
+    fn remove_old_backups(&mut self) -> std::io::Result<()> {
+        // The naming format used allows us to sort the backups by name and still get a sorting by
+        // creation time
+        let mut backups = std::fs::read_dir(&self.backup_dir)?
+            .filter_map(|res| res.map(|e| e.path()).ok())
+            .collect::<Vec<PathBuf>>();
+        backups.sort();
+
+        let max_backups: usize = self.max_backups.try_into().unwrap();
+
+        if backups.len() > max_backups {
+            let excess_backups = backups.len() - max_backups;
+
+            for backup in &backups[0..excess_backups] {
+                std::fs::remove_file(backup)?;
+            }
+        }
+
+        Ok(())
     }
 }