cvm: Add built-in swap config

Author: kvinwang

Cargo.lock

@@ -13,3 +13,4 @@ license.workspace = true
 serde = { workspace = true, features = ["derive"] }
 serde-human-bytes.workspace = true
 sha3.workspace = true
+size-parser = { workspace = true, features = ["serde"] }

dstack-types/Cargo.toml

@@ -4,6 +4,7 @@
 
 use serde::{Deserialize, Serialize};
 use serde_human_bytes as hex_bytes;
+use size_parser::human_size;
 
 #[derive(Deserialize, Serialize, Debug, Clone)]
 pub struct AppCompose {
@@ -39,6 +40,8 @@ pub struct AppCompose {
     pub no_instance_id: bool,
     #[serde(default = "default_true")]
     pub secure_time: bool,
+    #[serde(default, with = "human_size")]
+    pub swap_size: u64,
 }
 
 fn default_true() -> bool {

dstack-types/src/lib.rs

@@ -18,6 +18,7 @@ use dstack_types::{
     KeyProvider, KeyProviderInfo,
 };
 use fs_err as fs;
+use fs_err::os::unix::fs::OpenOptionsExt as _;
 use luks2::{
     LuksAf, LuksConfig, LuksDigest, LuksHeader, LuksJson, LuksKdf, LuksKeyslot, LuksSegment,
     LuksSegmentSize,
@@ -621,6 +622,43 @@ impl<'a> Stage0<'a> {
         }
     }
 
+    async fn setup_swap(&self, swap_size: u64) -> Result<()> {
+        let swap_file = self.args.mount_point.join("swapfile");
+        let swap_path = swap_file
+            .to_str()
+            .ok_or_else(|| anyhow!("Invalid swap file path"))?;
+
+        if swap_size == 0 {
+            if swap_file.exists() {
+                fs::remove_file(&swap_file).context("Failed to remove swap file")?;
+            }
+            return Ok(());
+        }
+
+        info!("Setting up swap file at {swap_path} (size {swap_size} bytes)");
+        {
+            let file = fs::OpenOptions::new()
+                .create(true)
+                .write(true)
+                .mode(0o600)
+                .custom_flags(libc::O_NOFOLLOW)
+                .open(&swap_file)
+                .context("Failed to open swap file")?;
+            file.set_len(swap_size)
+                .context("Failed to set swap file size")?;
+            file.sync_all().context("Failed to sync swap file")?;
+        }
+
+        let _ = cmd! {
+            chmod 600 $swap_path;
+            mkswap -f $swap_path;
+            swapon $swap_path;
+        }
+        .context("Failed to enable swap")?;
+
+        Ok(())
+    }
+
     async fn mount_data_disk(&self, initialized: bool, disk_crypt_key: &str) -> Result<()> {
         let name = "dstack_data_disk";
         let fs_dev = "/dev/mapper/".to_string() + name;
@@ -805,6 +843,9 @@ impl<'a> Stage0<'a> {
         self.vmm.notify_q("boot.progress", "unsealing env").await;
         self.mount_data_disk(is_initialized, &hex::encode(&app_keys.disk_crypt_key))
             .await?;
+
+        self.setup_swap(self.shared.app_compose.swap_size).await?;
+
         self.vmm
             .notify_q(
                 "instance.info",

dstack-util/src/system_setup.rs

@@ -173,22 +173,22 @@ pub fn create_manifest_from_vm_config(
         None => GpuConfig::default(),
     };
 
-    Ok(Manifest::builder()
-        .id(id)
-        .name(request.name.clone())
-        .app_id(app_id)
-        .image(request.image.clone())
-        .vcpu(request.vcpu)
-        .memory(request.memory)
-        .disk_size(request.disk_size)
-        .port_map(port_map)
-        .created_at_ms(now)
-        .hugepages(request.hugepages)
-        .pin_numa(request.pin_numa)
-        .gpus(gpus)
-        .kms_urls(request.kms_urls.clone())
-        .gateway_urls(request.gateway_urls.clone())
-        .build())
+    Ok(Manifest {
+        id,
+        name: request.name.clone(),
+        app_id,
+        vcpu: request.vcpu,
+        memory: request.memory,
+        disk_size: request.disk_size,
+        image: request.image.clone(),
+        port_map,
+        created_at_ms: now,
+        hugepages: request.hugepages,
+        pin_numa: request.pin_numa,
+        gpus: Some(gpus),
+        kms_urls: request.kms_urls.clone(),
+        gateway_urls: request.gateway_urls.clone(),
+    })
 }
 
 impl RpcHandler {