chore: bump version

.cargo/config.toml

@@ -1,2 +1,3 @@
 [alias]
-runs = "run -- paper --config data/config --backup data/backups --world data/worlds --jar data/paper.jar"
+runs = "run -- paper 1.19.4-545 --config data/config --backup data/backups --world data/worlds --jar data/paper.jar"
+runrs = "run --release -- paper 1.19.4-545 --config data/config --backup data/backups --world data/worlds --jar data/paper.jar"

.dockerignore

@@ -0,0 +1,5 @@
+*
+
+!Cargo.toml
+!Cargo.lock
+!src/

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://git.rustybever.be/Chewing_Bever/alex/src/branch/dev)
 
+## [0.2.0](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.2.0)
+
+### Added
+
+* Rudimentary signal handling for gently stopping server
+    * A single stop signal will trigger the Java process to shut down, but Alex
+      still expects to be run from a utility such as dumb-init
+* Properly back up entire config directory
+* Inject Java optimisation flags
+
 ## [0.1.1](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.1.1)
 
 ### Changed

Cargo.lock

@@ -10,11 +10,12 @@ checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 
 [[package]]
 name = "alex"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "chrono",
  "clap",
  "flate2",
+ "signal-hook",
  "tar",
 ]
 
@@ -383,6 +384,25 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "signal-hook"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "732768f1176d21d09e076c23a93123d40bba92d50c4058da34d45c8de8e682b9"
+dependencies = [
+ "libc",
+ "signal-hook-registry",
+]
+
+[[package]]
+name = "signal-hook-registry"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8229b473baa5980ac72ef434c4415e70c4b5e71b423043adb4ba059f89c99a1"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "strsim"
 version = "0.10.0"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "alex"
-version = "0.1.0"
+version = "0.2.0"
 description = "Wrapper around Minecraft server processes, designed to complement Docker image installations."
 authors = ["Jef Roosens"]
 edition = "2021"
@@ -15,6 +15,7 @@ flate2 = "1.0.26"
 # Used for backup filenames
 chrono = "0.4.26"
 clap = { version = "4.3.1", features = ["derive", "env"] }
+signal-hook = "0.3.15"
 
 [profile.release]
 lto = "fat"

Dockerfile

@@ -0,0 +1,64 @@
+FROM rust:1.70-alpine3.18 AS builder
+
+ARG DI_VER=1.2.5
+
+WORKDIR /app
+
+COPY . ./
+
+RUN apk add --no-cache build-base unzip curl && \
+    curl -Lo - "https://github.com/Yelp/dumb-init/archive/refs/tags/v${DI_VER}.tar.gz" | tar -xzf - && \
+    cd "dumb-init-${DI_VER}" && \
+    make SHELL=/bin/sh && \
+    mv dumb-init ..
+
+RUN cargo build && \
+    [ "$(readelf -d target/debug/alex | grep NEEDED | wc -l)" = 0 ]
+
+
+# We use ${:-} instead of a default value because the argument is always passed
+# to the build, it'll just be blank most likely
+FROM eclipse-temurin:17-jre-alpine
+
+# Build arguments
+ARG MC_VERSION=1.19.4
+ARG PAPERMC_VERSION=545
+
+RUN addgroup -Sg 1000 paper && \
+    adduser -SHG paper -u 1000 paper
+
+# Create worlds and config directory
+WORKDIR /app
+RUN mkdir -p worlds config/cache backups
+
+# Download server file
+ADD "https://papermc.io/api/v2/projects/paper/versions/$MC_VERSION/builds/$PAPERMC_VERSION/downloads/paper-$MC_VERSION-$PAPERMC_VERSION.jar" server.jar
+
+# Make sure the server user can access all necessary folders
+RUN chown -R paper:paper /app
+
+# Store the cache in an anonymous volume, which means it won't get stored in the other volumes
+VOLUME /app/config/cache
+VOLUME /app/backups
+
+COPY --from=builder /app/dumb-init /bin/dumb-init
+COPY --from=builder /app/target/debug/alex /bin/alex
+
+RUN chmod +x /bin/alex
+
+# Default value to keep users from eating up all ram accidentally
+ENV ALEX_XMS=1024 \
+    ALEX_XMX=2048 \
+    ALEX_JAR=/app/server.jar \
+    ALEX_CONFIG_DIR=/app/config \
+    ALEX_WORLD_DIR=/app/worlds \
+    ALEX_BACKUPS_DIR=/app/backups \
+    ALEX_SERVER_VERSION="${MC_VERSION}-${PAPERMC_VERSION}"
+
+# Document exposed ports
+EXPOSE 25565
+
+# Switch to non-root user
+USER paper:paper
+
+ENTRYPOINT ["/bin/alex", "paper"]

src/main.rs

@@ -1,4 +1,6 @@
 mod server;
+mod signals;
+mod stdin;
 
 use clap::Parser;
 use server::ServerType;
@@ -79,7 +81,8 @@ fn backups_thread(counter: Arc<Mutex<server::ServerProcess>>, frequency: u64) {
     }
 }
 
-fn main() {
+fn main() -> io::Result<()> {
+    let (_, mut signals) = signals::install_signal_handlers()?;
     let cli = Cli::parse();
 
     let cmd = server::ServerCommand::new(cli.type_, &cli.server_version)
@@ -91,33 +94,17 @@ fn main() {
         .xms(cli.xms)
         .xmx(cli.xmx)
         .max_backups(cli.max_backups);
-    let counter = Arc::new(Mutex::new(cmd.spawn().expect("Failed to start server.")));
+    let counter = Arc::new(Mutex::new(cmd.spawn()?));
 
     if cli.frequency > 0 {
         let clone = Arc::clone(&counter);
         std::thread::spawn(move || backups_thread(clone, cli.frequency));
     }
 
-    let stdin = io::stdin();
-    let input = &mut String::new();
+    // Spawn thread that handles the main stdin loop
+    let clone = Arc::clone(&counter);
+    std::thread::spawn(move || stdin::handle_stdin(clone));
 
-    loop {
-        input.clear();
-
-        if stdin.read_line(input).is_err() {
-            continue;
-        };
-
-        {
-            let mut server = counter.lock().unwrap();
-
-            if let Err(e) = server.send_command(input) {
-                println!("{}", e);
-            };
-        }
-
-        if input.trim() == "stop" {
-            break;
-        }
-    }
+    // Signal handler loop exits the process when necessary
+    signals::handle_signals(&mut signals, counter)
 }

src/server/command.rs

@@ -113,16 +113,57 @@ impl ServerCommand {
         let backup_dir = self.backup_dir.canonicalize()?;
 
         self.accept_eula()?;
+        let mut cmd = Command::new(&self.java);
 
-        let child = Command::new(&self.java)
-            .current_dir(&config_dir)
+        // Apply JVM optimisation flags
+        // https://aikar.co/2018/07/02/tuning-the-jvm-g1gc-garbage-collector-flags-for-minecraft/
+        cmd.arg(format!("-Xms{}M", self.xms))
+            .arg(format!("-Xmx{}M", self.xmx))
+            .args([
+                "-XX:+UseG1GC",
+                "-XX:+ParallelRefProcEnabled",
+                "-XX:MaxGCPauseMillis=200",
+                "-XX:+UnlockExperimentalVMOptions",
+                "-XX:+DisableExplicitGC",
+                "-XX:+AlwaysPreTouch",
+                "-XX:G1HeapWastePercent=5",
+                "-XX:G1MixedGCCountTarget=4",
+                "-XX:G1MixedGCLiveThresholdPercent=90",
+                "-XX:G1RSetUpdatingPauseTimePercent=5",
+                "-XX:SurvivorRatio=32",
+                "-XX:+PerfDisableSharedMem",
+                "-XX:MaxTenuringThreshold=1",
+                "-Dusing.aikars.flags=https://mcflags.emc.gs",
+                "-Daikars.new.flags=true",
+            ]);
+
+        if self.xms > 12 * 1024 {
+            cmd.args([
+                "-XX:G1NewSizePercent=40",
+                "-XX:G1MaxNewSizePercent=50",
+                "-XX:G1HeapRegionSize=16M",
+                "-XX:G1ReservePercent=15",
+                "-XX:InitiatingHeapOccupancyPercent=20",
+            ]);
+        } else {
+            cmd.args([
+                "-XX:G1NewSizePercent=30",
+                "-XX:G1MaxNewSizePercent=40",
+                "-XX:G1HeapRegionSize=8M",
+                "-XX:G1ReservePercent=15",
+                "-XX:InitiatingHeapOccupancyPercent=15",
+            ]);
+        }
+
+        cmd.current_dir(&config_dir)
             .arg("-jar")
             .arg(&jar)
             .arg("--universe")
             .arg(&world_dir)
             .arg("--nogui")
-            .stdin(Stdio::piped())
-            .spawn()?;
+            .stdin(Stdio::piped());
+
+        let child = cmd.spawn()?;
 
         Ok(ServerProcess::new(
             self.type_,

src/server/process.rs

@@ -2,7 +2,7 @@ use crate::server::ServerType;
 use flate2::write::GzEncoder;
 use flate2::Compression;
 use std::io::Write;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::process::Child;
 
 #[link(name = "c")]
@@ -67,6 +67,10 @@ impl ServerProcess {
         Ok(())
     }
 
+    pub fn kill(&mut self) -> std::io::Result<()> {
+        self.child.kill()
+    }
+
     /// 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<()> {
@@ -89,7 +93,11 @@ impl ServerProcess {
         // 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")?;
+        if res.is_ok() {
+            self.custom("say server backed up successfully")?;
+        } else {
+            self.custom("an error occured while backing up the server")?;
+        }
 
         res
     }
@@ -108,11 +116,21 @@ impl ServerProcess {
 
         tar.append_dir_all("worlds", &self.world_dir)?;
 
-        // We don't store all files in the config, as this would include caches
-        tar.append_path_with_name(
-            self.config_dir.join("server.properties"),
-            "config/server.properties",
-        )?;
+        // Add all files from the config directory that aren't the cache
+        for entry in self
+            .config_dir
+            .read_dir()?
+            .filter_map(|e| e.ok())
+            .filter(|e| e.file_name() != "cache")
+        {
+            let tar_path = Path::new("config").join(entry.file_name());
+
+            if entry.file_type()?.is_dir() {
+                tar.append_dir_all(tar_path, entry.path())?;
+            } else {
+                tar.append_path_with_name(entry.path(), tar_path)?;
+            }
+        }
 
         // We add a file to the backup describing for what version it was made
         let info = format!("{} {}", self.type_, self.version);
@@ -128,8 +146,6 @@ impl ServerProcess {
 
         tar.append_data(&mut header, "info.txt", info_bytes)?;
 
-        // tar.append_dir_all("config", &self.config_dir)?;
-
         // Backup file gets finalized in the drop
 
         Ok(())
@@ -139,7 +155,9 @@ impl ServerProcess {
     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)?
+        let mut backups = self
+            .backup_dir
+            .read_dir()?
             .filter_map(|res| res.map(|e| e.path()).ok())
             .collect::<Vec<PathBuf>>();
         backups.sort();

src/signals.rs

@@ -0,0 +1,68 @@
+use std::io;
+use std::sync::atomic::AtomicBool;
+use std::sync::{Arc, Mutex};
+
+use signal_hook::consts::TERM_SIGNALS;
+use signal_hook::flag;
+use signal_hook::iterator::{Signals, SignalsInfo};
+
+use crate::server;
+
+/// Install the required signal handlers for terminating signals.
+pub fn install_signal_handlers() -> io::Result<(Arc<AtomicBool>, SignalsInfo)> {
+    let term = Arc::new(AtomicBool::new(false));
+
+    // For each terminating signal, we register both a shutdown handler and a handler that sets an
+    // atomic bool. With this, the process will get killed immediately once it receives a second
+    // termination signal (e.g. a double ctrl-c).
+    // https://docs.rs/signal-hook/0.3.15/signal_hook/#a-complex-signal-handling-with-a-background-thread
+    for sig in TERM_SIGNALS {
+        // When terminated by a second term signal, exit with exit code 1.
+        // This will do nothing the first time (because term_now is false).
+        flag::register_conditional_shutdown(*sig, 1, Arc::clone(&term))?;
+        // But this will "arm" the above for the second time, by setting it to true.
+        // The order of registering these is important, if you put this one first, it will
+        // first arm and then terminate ‒ all in the first round.
+        flag::register(*sig, Arc::clone(&term))?;
+    }
+
+    let signals = TERM_SIGNALS;
+
+    Ok((term, Signals::new(signals)?))
+}
+
+/// Loop that handles terminating signals as they come in.
+pub fn handle_signals(
+    signals: &mut SignalsInfo,
+    counter: Arc<Mutex<server::ServerProcess>>,
+) -> io::Result<()> {
+    let mut force = false;
+
+    // We only register terminating signals, so we don't need to differentiate between what kind of
+    // signal came in
+    for _ in signals {
+        // If term is already true, this is the second signal, meaning we kill the process
+        // immediately.
+        // This will currently not work, as the initial stop command will block the kill from
+        // happening.
+        if force {
+            let mut server = counter.lock().unwrap();
+            return server.kill();
+        }
+        // The stop command runs in a separate thread to avoid blocking the signal handling loop.
+        // After stopping the server, the thread terminates the process.
+        else {
+            let clone = Arc::clone(&counter);
+
+            std::thread::spawn(move || {
+                let mut server = clone.lock().unwrap();
+                let _ = server.stop();
+                std::process::exit(0);
+            });
+        }
+
+        force = true;
+    }
+
+    Ok(())
+}

src/stdin.rs

@@ -0,0 +1,29 @@
+use std::io;
+use std::sync::{Arc, Mutex};
+
+use crate::server;
+
+pub fn handle_stdin(counter: Arc<Mutex<server::ServerProcess>>) {
+    let stdin = io::stdin();
+    let input = &mut String::new();
+
+    loop {
+        input.clear();
+
+        if stdin.read_line(input).is_err() {
+            continue;
+        };
+
+        {
+            let mut server = counter.lock().unwrap();
+
+            if let Err(e) = server.send_command(input) {
+                println!("{}", e);
+            };
+        }
+
+        if input.trim() == "stop" {
+            std::process::exit(0);
+        }
+    }
+}