install: Add alongside-cleanup systemd service

This will remove all rpms and containers/images from the previous
install (found in /sysroot) on reboot after running `install to-existing-root.`

Signed-off-by: ckyrouac <[email protected]>

Author: ckyrouac

Makefile

@@ -28,6 +28,7 @@ install:
 	install -d -m 0755 $(DESTDIR)/$(prefix)/lib/systemd/system/multi-user.target.wants
 	ln -s ../bootc-status-updated.path $(DESTDIR)/$(prefix)/lib/systemd/system/multi-user.target.wants/bootc-status-updated.path
 	ln -s ../bootc-status-updated-onboot.target $(DESTDIR)/$(prefix)/lib/systemd/system/multi-user.target.wants/bootc-status-updated-onboot.target
+	ln -s ../bootc-install-alongside-cleanup.service $(DESTDIR)/$(prefix)/lib/systemd/system/multi-user.target.wants/bootc-install-alongside-cleanup.service
 	install -D -m 0644 -t $(DESTDIR)/$(prefix)/share/doc/bootc/baseimage/base/usr/lib/ostree/ baseimage/base/usr/lib/ostree/prepare-root.conf
 	install -d -m 755 $(DESTDIR)/$(prefix)/share/doc/bootc/baseimage/base/sysroot
 	cp -PfT baseimage/base/ostree $(DESTDIR)/$(prefix)/share/doc/bootc/baseimage/base/ostree 

contrib/packaging/bootc.spec

@@ -72,6 +72,7 @@ Recommends: podman
 This package provides a utility to simplify reinstalling the current system to a given bootc image.
 
 %global system_reinstall_bootc_install_podman_path %{_prefix}/lib/system-reinstall-bootc/install-podman
+%global install_alongside_cleanup %{_prefix}/lib/bootc/install-alongside-cleanup
 
 %prep
 %autosetup -p1 -a1
@@ -82,6 +83,7 @@ cat vendor-config.toml >> .cargo/config.toml
 rm vendor-config.toml
 
 %build
+export INSTALL_ALONGSIDE_CLEANUP=%{install_alongside_cleanup}
 # Build the main bootc binary
 %if 0%{?fedora} || 0%{?rhel} >= 10
     %cargo_build %{?with_rhsm:-f rhsm}
@@ -115,13 +117,26 @@ sed -i -e '/https:\/\//d' cargo-vendor.txt
 %if %{with ostree_ext}
 make install-ostree-hooks DESTDIR=%{?buildroot}
 %endif
+
 mkdir -p %{buildroot}/%{dirname:%{system_reinstall_bootc_install_podman_path}}
 cat >%{?buildroot}/%{system_reinstall_bootc_install_podman_path} <<EOF
 #!/bin/bash
 exec dnf -y install podman
 EOF
 chmod +x %{?buildroot}/%{system_reinstall_bootc_install_podman_path}
 
+mkdir -p %{buildroot}/%{dirname:%{install_alongside_cleanup}}
+cat >%{?buildroot}/%{install_alongside_cleanup} <<EOF
+#!/bin/bash
+set -xeuo pipefail
+mount -o remount,rw /sysroot
+rpm -qa --root=/sysroot --dbpath=/usr/lib/sysimage/rpm | xargs rpm -e --root=/sysroot --dbpath=/usr/lib/sysimage/rpm
+
+mount --bind -o rw /sysroot/var/lib/containers /var/lib/containers
+podman system prune --all
+EOF
+chmod +x %{?buildroot}/%{install_alongside_cleanup}
+
 %if %{with check}
 %check
 %cargo_test
@@ -142,6 +157,7 @@ chmod +x %{?buildroot}/%{system_reinstall_bootc_install_podman_path}
 %{_unitdir}/*
 %{_docdir}/bootc/*
 %{_mandir}/man*/bootc*
+%{install_alongside_cleanup}
 
 %files -n system-reinstall-bootc
 %{_bindir}/system-reinstall-bootc

lib/src/install.rs

@@ -69,6 +69,8 @@ const BOOT: &str = "boot";
 const RUN_BOOTC: &str = "/run/bootc";
 /// The default path for the host rootfs
 const ALONGSIDE_ROOT_MOUNT: &str = "/target";
+/// Global flag to signal the booted system was provisioned via an alongside bootc install
+const ALONGSIDE_INSTALL: &str = ".bootc-installed-alongside";
 /// This is an ext4 special directory we need to ignore.
 const LOST_AND_FOUND: &str = "lost+found";
 /// The filename of the composefs EROFS superblock; TODO move this into ostree
@@ -1460,7 +1462,7 @@ impl BoundImages {
     }
 }
 
-async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Result<()> {
+async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Result<Storage> {
     if matches!(state.selinux_state, SELinuxFinalState::ForceTargetDisabled) {
         rootfs.kargs.push("selinux=0".to_string());
     }
@@ -1489,7 +1491,8 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
     let bound_images = BoundImages::from_state(state).await?;
 
     // Initialize the ostree sysroot (repo, stateroot, etc.)
-    {
+    
+    let sysroot = {
         let (sysroot, has_ostree, imgstore) = initialize_ostree_root(state, rootfs).await?;
 
         install_with_sysroot(
@@ -1502,9 +1505,11 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
             &imgstore,
         )
         .await?;
+
+        sysroot
         // We must drop the sysroot here in order to close any open file
         // descriptors.
-    }
+    };
 
     // Run this on every install as the penultimate step
     install_finalize(&rootfs.physical_root_path).await?;
@@ -1517,7 +1522,7 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
         }
     }
 
-    Ok(())
+    Ok(sysroot)
 }
 
 fn installation_complete() {
@@ -1950,7 +1955,17 @@ pub(crate) async fn install_to_filesystem(
         skip_finalize,
     };
 
-    install_to_filesystem_impl(&state, &mut rootfs).await?;
+    let sysroot = install_to_filesystem_impl(&state, &mut rootfs).await?;
+
+    // add a flag to signify the system was provisioned via an alongside install
+    // this is used by things like bootc-installed-alongside-cleanup.service
+    let sysroot_dir = crate::utils::sysroot_dir(&sysroot.sysroot)?;
+    if matches!(fsopts.replace, Some(ReplaceMode::Alongside))
+        && !sysroot_dir.try_exists(ALONGSIDE_INSTALL)?
+    {
+        tracing::debug!("Writing {ALONGSIDE_INSTALL}");
+        sysroot_dir.atomic_write(ALONGSIDE_INSTALL, b"")?;
+    }
 
     // Drop all data about the root except the path to ensure any file descriptors etc. are closed.
     drop(rootfs);

systemd/bootc-install-alongside-cleanup.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Cleanup previous the installation after an alongside installation
+Documentation=man:bootc(8)
+ConditionPathExists=/sysroot/.bootc-installed-alongside
+
+[Service]
+Type=oneshot
+ExecStart=/usr/lib/bootc/install-alongside-cleanup
+PrivateMounts=true
+
+[Install]
+WantedBy=multi-user.target