vume:base property to track full snapshot name

Author: scttnlsn

README.md

@@ -151,20 +151,18 @@ vume <command> --help
 
 ## Customizing the rootfs
 
-You can create a custom base image from a running VM. The active rootfs version is tracked
-via the `vume:latest` ZFS user property on `vume/rootfs`, so you can create new versions without
-affecting existing VMs.
+You can create a custom base image from a running VM. The active rootfs snapshot is tracked
+via the `vume:base` ZFS user property on the pool, which stores the full snapshot path.
 
 ```bash
 # 1. Customize a running VM, e.g.
 sudo vume exec <vm-id> "apt install -y python3 nginx"
 
-# 2. Snapshot the customized VM and create a new rootfs version
+# 2. Snapshot the customized VM
 sudo zfs snapshot vume/<vm-id>@<version>
-sudo zfs send vume/<vm-id>@<version> | sudo zfs receive vume/rootfs@<version>
 
-# 3. Point to the new version
-sudo zfs set vume:latest=<version> vume/rootfs
+# 3. Point to the new snapshot
+sudo zfs set vume:base=vume/<vm-id>@<version> vume
 ```
 
-All future VMs will clone from the new version. Existing VMs are unaffected.
+All future VMs will clone from the new snapshot. Existing VMs are unaffected.

src/vm.rs

@@ -161,26 +161,19 @@ impl VM {
 fn resolve_rootfs_snapshot() -> Result<String> {
     let pool = &get().zfs_pool;
     let output = Command::new("zfs")
-        .args([
-            "get",
-            "-H",
-            "-o",
-            "value",
-            "vume:latest",
-            &format!("{}/rootfs", pool),
-        ])
+        .args(["get", "-H", "-o", "value", "vume:base", pool])
         .output()
         .context("Failed to run zfs get")?;
 
     if !output.status.success() {
         bail!("zfs get failed");
     }
 
-    let version = String::from_utf8_lossy(&output.stdout).trim().to_string();
-    if version.is_empty() || version == "-" {
-        bail!("vume:latest property not set on {}/rootfs", pool);
+    let snapshot = String::from_utf8_lossy(&output.stdout).trim().to_string();
+    if snapshot.is_empty() || snapshot == "-" {
+        bail!("vume:base property not set on {}", pool);
     }
-    Ok(format!("{}/rootfs@{}", pool, version))
+    Ok(snapshot)
 }
 
 /// Remove a VM's filesystem, ZFS dataset, and state record.

vume.sh

@@ -18,8 +18,8 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
 POOL_DEVICE=""
 ROOTFS_PATH=""
-ROOTFS_SIZE="2G"
-ZVOL_SIZE="2G"
+ROOTFS_SIZE="10G"
+ZVOL_SIZE="10G"
 SSH_KEY=""
 POOL_NAME=""
 
@@ -163,7 +163,7 @@ cmd_setup() {
     else
         echo ":: creating snapshot '${POOL_NAME}/rootfs@base'"
         zfs snapshot "${POOL_NAME}/rootfs@base"
-        zfs set vume:latest=base "${POOL_NAME}/rootfs"
+        zfs set vume:base=${POOL_NAME}/rootfs@base "${POOL_NAME}"
     fi
 
     echo ""