Add support for (weakly) lifecycle bound podman images

This is a working PoC implementation of part of
#128

Demo:

```
$ cat Containerfile
FROM localhost/bootc
COPY *.image /usr/share/containers/systemd
$ cat foo.image
[Container]
Image=quay.io/centos/centos:stream9
$ podman build -t localhost/testbootc .
$ podman-bootc run localhost/testbootc
...
[root@ibm-p8-kvm-03-guest-02 ~]# podman images
REPOSITORY             TAG         IMAGE ID      CREATED       SIZE
quay.io/centos/centos  stream9     75a875ea6cd8  43 hours ago  163 MB
[root@ibm-p8-kvm-03-guest-02 ~]#
```

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

lib/Cargo.toml

@@ -47,6 +47,7 @@ tempfile = "3.10.1"
 toml = "0.8.12"
 xshell = { version = "0.2.6", optional = true }
 uuid = { version = "1.8.0", features = ["v4"] }
+rust-ini = "0.21.0"
 
 [features]
 default = ["install"]

lib/src/deploy.rs

@@ -2,7 +2,9 @@
 //!
 //! Create a merged filesystem tree with the image and mounted configmaps.
 
+use std::collections::HashSet;
 use std::io::{BufRead, Write};
+use std::process::Command;
 
 use anyhow::Ok;
 use anyhow::{anyhow, Context, Result};
@@ -18,7 +20,9 @@ use ostree_ext::container::store::PrepareResult;
 use ostree_ext::ostree;
 use ostree_ext::ostree::Deployment;
 use ostree_ext::sysroot::SysrootLock;
+use rustix::fd::BorrowedFd;
 
+use crate::podman;
 use crate::spec::ImageReference;
 use crate::spec::{BootOrder, HostSpec};
 use crate::status::labels_of_config;
@@ -113,6 +117,53 @@ pub(crate) fn check_bootc_label(config: &ostree_ext::oci_spec::image::ImageConfi
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) struct BoundState {
+    pub(crate) total_images: usize,
+    pub(crate) bound_images: HashSet<String>,
+}
+
+impl BoundState {
+    pub(crate) fn is_empty(&self) -> bool {
+        self.bound_images.is_empty()
+    }
+
+    pub(crate) fn print(&self) {
+        if self.total_images == 0 {
+            println!("No podman .image definitions found");
+        } else {
+            println!("podman systemd .image entries: {}", self.total_images);
+            println!("Bound images: {}", self.bound_images.len());
+        }
+    }
+}
+
+pub(crate) fn query_bound_state(root: &Dir) -> Result<BoundState> {
+    let (total_images, bound_images) = podman::list_container_images(root)?;
+    tracing::debug!("images={total_images} bound={}", bound_images.len());
+    Ok(BoundState {
+        total_images,
+        bound_images,
+    })
+}
+
+/// Pre-fetch e.g. podman `.image` files which reference external images.  This
+/// expects that podman sees e.g. `/var` set up as the deployment root.
+#[context("Fetching bound state")]
+pub(crate) async fn fetch_bound_state(state: &BoundState) -> Result<()> {
+    for image in state.bound_images.iter() {
+        let mut cmd = Command::new("podman");
+        cmd.args(["pull", image.as_str()]);
+        let mut cmd = tokio::process::Command::from(cmd);
+        cmd.kill_on_drop(true);
+        let status = cmd.status().await.context("bound podman pull")?;
+        if !status.success() {
+            anyhow::bail!("Failed to pull {image}");
+        }
+    }
+    Ok(())
+}
+
 /// Write container fetch progress to standard output.
 async fn handle_layer_progress_print(
     mut layers: tokio::sync::mpsc::Receiver<ostree_container::store::ImportProgress>,
@@ -278,19 +329,20 @@ async fn deploy(
     stateroot: &str,
     image: &ImageState,
     origin: &glib::KeyFile,
-) -> Result<()> {
+) -> Result<Deployment> {
     let stateroot = Some(stateroot);
     // Copy to move into thread
     let cancellable = gio::Cancellable::NONE;
-    let _new_deployment = sysroot.stage_tree_with_options(
-        stateroot,
-        image.ostree_commit.as_str(),
-        Some(origin),
-        merge_deployment,
-        &Default::default(),
-        cancellable,
-    )?;
-    Ok(())
+    sysroot
+        .stage_tree_with_options(
+            stateroot,
+            image.ostree_commit.as_str(),
+            Some(origin),
+            merge_deployment,
+            &Default::default(),
+            cancellable,
+        )
+        .map_err(Into::into)
 }
 
 #[context("Generating origin")]
@@ -307,6 +359,7 @@ fn origin_from_imageref(imgref: &ImageReference) -> Result<glib::KeyFile> {
 
 /// Stage (queue deployment of) a fetched container image.
 #[context("Staging")]
+#[allow(unsafe_code)]
 pub(crate) async fn stage(
     sysroot: &SysrootLock,
     stateroot: &str,
@@ -315,14 +368,20 @@ pub(crate) async fn stage(
 ) -> Result<()> {
     let merge_deployment = sysroot.merge_deployment(Some(stateroot));
     let origin = origin_from_imageref(spec.image)?;
-    crate::deploy::deploy(
+    let deployment = crate::deploy::deploy(
         sysroot,
         merge_deployment.as_ref(),
         stateroot,
         image,
         &origin,
     )
     .await?;
+    let sysroot_fd = Dir::reopen_dir(unsafe { &BorrowedFd::borrow_raw(sysroot.fd()) })?;
+    let deployment_dir = sysroot_fd.open_dir(sysroot.deployment_dirpath(&deployment))?;
+    // TODO: Make things atomic here by not completing the staging unless we can fetch
+    // the new images.
+    let bound = query_bound_state(&deployment_dir)?;
+    fetch_bound_state(&bound).await?;
     crate::deploy::cleanup(sysroot).await?;
     println!("Queued for next boot: {:#}", spec.image);
     if let Some(version) = image.version.as_deref() {

lib/src/install.rs

@@ -40,6 +40,7 @@ use serde::{Deserialize, Serialize};
 
 use self::baseline::InstallBlockDeviceOpts;
 use crate::containerenv::ContainerExecutionInfo;
+use crate::deploy::query_bound_state;
 use crate::mount::Filesystem;
 use crate::task::Task;
 use crate::utils::sigpolicy_from_opts;
@@ -530,11 +531,17 @@ pub(crate) fn print_configuration() -> Result<()> {
     serde_json::to_writer(stdout, &install_config).map_err(Into::into)
 }
 
+pub(crate) struct InitializedRoot {
+    aleph: InstallAleph,
+    deployment: Dir,
+    var: Dir,
+}
+
 #[context("Creating ostree deployment")]
 async fn initialize_ostree_root_from_self(
     state: &State,
     root_setup: &RootSetup,
-) -> Result<InstallAleph> {
+) -> Result<InitializedRoot> {
     let sepolicy = state.load_policy()?;
     let sepolicy = sepolicy.as_ref();
 
@@ -667,6 +674,10 @@ async fn initialize_ostree_root_from_self(
     let root = rootfs_dir
         .open_dir(path.as_str())
         .context("Opening deployment dir")?;
+    let varpath = format!("ostree/deploy/{stateroot}/var");
+    let var = rootfs_dir
+        .open_dir(&varpath)
+        .with_context(|| format!("Opening {varpath}"))?;
 
     // And do another recursive relabeling pass over the ostree-owned directories
     // but avoid recursing into the deployment root (because that's a *distinct*
@@ -715,7 +726,11 @@ async fn initialize_ostree_root_from_self(
         selinux: state.selinux_state.to_aleph().to_string(),
     };
 
-    Ok(aleph)
+    Ok(InitializedRoot {
+        aleph,
+        deployment: root,
+        var: var,
+    })
 }
 
 /// Run a command in the host mount namespace
@@ -1180,15 +1195,29 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
     tracing::debug!("boot uuid={boot_uuid}");
 
     // Write the aleph data that captures the system state at the time of provisioning for aid in future debugging.
-    {
-        let aleph = initialize_ostree_root_from_self(state, rootfs).await?;
-        rootfs
-            .rootfs_fd
-            .atomic_replace_with(BOOTC_ALEPH_PATH, |f| {
-                serde_json::to_writer(f, &aleph)?;
-                anyhow::Ok(())
-            })
-            .context("Writing aleph version")?;
+    let inst = initialize_ostree_root_from_self(state, rootfs).await?;
+    rootfs
+        .rootfs_fd
+        .atomic_replace_with(BOOTC_ALEPH_PATH, |f| {
+            serde_json::to_writer(f, &inst.aleph)?;
+            anyhow::Ok(())
+        })
+        .context("Writing aleph version")?;
+
+    let bound = query_bound_state(&inst.deployment)?;
+    bound.print();
+    if !bound.is_empty() {
+        println!();
+        Task::new("Mounting deployment /var", "mount")
+            .args(["--bind", ".", "/var"])
+            .cwd(&inst.var)?
+            .run()?;
+        // podman needs this
+        Task::new("Initializing /var/tmp", "systemd-tmpfiles")
+            .args(["--create", "--boot", "--prefix=/var/tmp"])
+            .verbose()
+            .run()?;
+        crate::deploy::fetch_bound_state(&bound).await?;
     }
 
     crate::bootloader::install_via_bootupd(&rootfs.device, &rootfs.rootfs, &state.config_opts)?;

lib/src/lib.rs

@@ -45,7 +45,6 @@ mod k8sapitypes;
 mod kernel;
 #[cfg(feature = "install")]
 pub(crate) mod mount;
-#[cfg(feature = "install")]
 mod podman;
 pub mod spec;