libvirt-run: Add --update-from-host

This streamlines the UX of upgrading from a local build; it's
part of the idea of #86
but this is a lot smaller than that.

Signed-off-by: Colin Walters <[email protected]>

Author: cgwalters

crates/kit/src/cache_metadata.rs

@@ -34,10 +34,16 @@ struct CacheInputs {
     /// This is crucial because it determines the upgrade source for the installed system
     source_imgref: String,
 
+    /// Target transport
+    #[serde(skip_serializing_if = "Option::is_none")]
+    target_transport: Option<String>,
+
     /// Filesystem type used for installation (e.g., "ext4", "xfs", "btrfs")
+    #[serde(skip_serializing_if = "Option::is_none")]
     filesystem: Option<String>,
 
     /// Root filesystem size if specified
+    #[serde(skip_serializing_if = "Option::is_none")]
     root_size: Option<String>,
 
     /// Whether to use composefs-native storage
@@ -60,6 +66,9 @@ pub struct DiskImageMetadata {
     /// This is crucial because it determines the upgrade source for the installed system
     pub source_imgref: String,
 
+    /// Target transport
+    pub target_transport: Option<String>,
+
     /// Filesystem type used for installation (e.g., "ext4", "xfs", "btrfs")
     pub filesystem: Option<String>,
 
@@ -82,6 +91,7 @@ impl DiskImageMetadata {
         let inputs = CacheInputs {
             image_digest: self.digest.clone(),
             source_imgref: self.source_imgref.clone(),
+            target_transport: self.target_transport.clone(),
             filesystem: self.filesystem.clone(),
             root_size: self.root_size.clone(),
             composefs_backend: self.composefs_backend,
@@ -169,6 +179,7 @@ impl DiskImageMetadata {
             version: 1,
             digest: image_digest.to_owned(),
             source_imgref: source_imgref.to_owned(),
+            target_transport: options.target_transport.clone(),
             filesystem: options.filesystem.clone(),
             root_size: options.root_size.clone(),
             kernel_args: options.karg.clone(),
@@ -326,6 +337,7 @@ mod tests {
         let inputs = CacheInputs {
             image_digest: "sha256:abc123".to_string(),
             source_imgref: "quay.io/test/image:v1".to_string(),
+            target_transport: None,
             filesystem: Some("ext4".to_string()),
             root_size: Some("20G".to_string()),
             kernel_args: vec!["console=ttyS0".to_string()],

crates/kit/src/install_options.rs

@@ -29,6 +29,10 @@ pub struct InstallOptions {
     )]
     pub storage_path: Option<Utf8PathBuf>,
 
+    /// The transport; e.g. oci, oci-archive, containers-storage.  Defaults to `registry`
+    #[clap(long)]
+    pub target_transport: Option<String>,
+
     #[clap(long)]
     /// Set a kernel argument
     pub karg: Vec<String>,
@@ -57,6 +61,11 @@ impl InstallOptions {
             args.push(format!("--karg={k}"));
         }
 
+        if let Some(ref t) = self.target_transport {
+            args.push("--target-transport".to_string());
+            args.push(t.clone());
+        }
+
         if self.composefs_backend {
             args.push("--composefs-backend".to_owned());
         }

crates/kit/src/libvirt/run.rs

@@ -22,6 +22,9 @@ use crate::xml_utils;
 /// SSH wait timeout in seconds
 const SSH_WAIT_TIMEOUT_SECONDS: u64 = 180;
 
+/// Transport type for updating from host container storage
+const UPDATE_FROM_HOST_TRANSPORT: &str = "containers-storage";
+
 /// Create a virsh command with optional connection URI
 pub(super) fn virsh_command(connect_uri: Option<&str>) -> Result<std::process::Command> {
     let mut cmd = std::process::Command::new("virsh");
@@ -264,6 +267,11 @@ pub struct LibvirtRunOpts {
     #[clap(long = "bind-storage-ro")]
     pub bind_storage_ro: bool,
 
+    /// Implies --bind-storage-ro, but also configure to update from the host
+    /// container storage by default.
+    #[clap(long, conflicts_with = "target_transport")]
+    pub update_from_host: bool,
+
     /// Firmware type for the VM (defaults to uefi-secure)
     #[clap(long, default_value = "uefi-secure")]
     pub firmware: FirmwareType,
@@ -381,7 +389,7 @@ fn wait_for_ssh_ready(
 }
 
 /// Execute the libvirt run command
-pub fn run(global_opts: &crate::libvirt::LibvirtOptions, opts: LibvirtRunOpts) -> Result<()> {
+pub fn run(global_opts: &crate::libvirt::LibvirtOptions, mut opts: LibvirtRunOpts) -> Result<()> {
     use crate::images;
 
     // Validate labels don't contain commas
@@ -417,6 +425,11 @@ pub fn run(global_opts: &crate::libvirt::LibvirtOptions, opts: LibvirtRunOpts) -
     let image_digest = inspect.digest.to_string();
     debug!("Image digest: {}", image_digest);
 
+    if opts.update_from_host {
+        opts.bind_storage_ro = true;
+        opts.install.target_transport = Some(UPDATE_FROM_HOST_TRANSPORT.to_owned());
+    }
+
     // Phase 1: Find or create a base disk image
     let base_disk_path = crate::libvirt::base_disks::find_or_create_base_disk(
         &opts.image,

docs/src/man/bcvk-libvirt-run.md

@@ -57,6 +57,10 @@ Run a bootable container as a persistent VM
 
     Path to host container storage (auto-detected if not specified)
 
+**--target-transport**=*TARGET_TRANSPORT*
+
+    The transport; e.g. oci, oci-archive, containers-storage.  Defaults to `registry`
+
 **--karg**=*KARG*
 
     Set a kernel argument
@@ -103,6 +107,10 @@ Run a bootable container as a persistent VM
 
     Mount host container storage (RO) at /run/host-container-storage
 
+**--update-from-host**
+
+    Implies --bind-storage-ro, but also configure to update from the host container storage by default
+
 **--firmware**=*FIRMWARE*
 
     Firmware type for the VM (defaults to uefi-secure)

docs/src/man/bcvk-libvirt-upload.md

@@ -45,6 +45,10 @@ Upload bootc disk images to libvirt with metadata annotations
 
     Path to host container storage (auto-detected if not specified)
 
+**--target-transport**=*TARGET_TRANSPORT*
+
+    The transport; e.g. oci, oci-archive, containers-storage.  Defaults to `registry`
+
 **--karg**=*KARG*
 
     Set a kernel argument

docs/src/man/bcvk-to-disk.md

@@ -47,6 +47,10 @@ The installation process:
 
     Path to host container storage (auto-detected if not specified)
 
+**--target-transport**=*TARGET_TRANSPORT*
+
+    The transport; e.g. oci, oci-archive, containers-storage.  Defaults to `registry`
+
 **--karg**=*KARG*
 
     Set a kernel argument