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WIP: Add support for --replace-mode=alongside for ostree target
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Ironically our support for `--replace-mode=alongside` breaks
when we're targeting an already extant ostree host, because when
we first blow away the `/boot` directory, this means the ostree
stack loses its knowledge that we're in a booted deployment,
and will attempt to GC it...

ostreedev/ostree-rs-ext@8fa019b
is a key part of the fix for that.

However, a notable improvement we can do here is to grow this
whole thing into a real "factory reset" mode, and this will
be a compelling answer to
coreos/fedora-coreos-tracker#399

To implement this though we need to support configuring the
stateroot and not just hardcode `default`.

Signed-off-by: Colin Walters <[email protected]>
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cgwalters committed Oct 2, 2023
1 parent bb163bc commit 22671b5
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Showing 3 changed files with 80 additions and 10 deletions.
3 changes: 3 additions & 0 deletions Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -33,3 +33,6 @@ exclude-crate-paths = [ { name = "libz-sys", exclude = "src/zlib" },
{ name = "k8s-openapi", exclude = "src/v1_25" },
{ name = "k8s-openapi", exclude = "src/v1_27" },
]

[patch.crates-io]
ostree-ext = { path = "../../ostreedev/ostree-rs-ext/lib" }
45 changes: 35 additions & 10 deletions lib/src/install.rs
Original file line number Diff line number Diff line change
Expand Up @@ -459,11 +459,17 @@ async fn initialize_ostree_root_from_self(

// TODO: make configurable?
let stateroot = STATEROOT_DEFAULT;
Task::new_and_run(
"Initializing ostree layout",
"ostree",
["admin", "init-fs", "--modern", rootfs.as_str()],
)?;
let has_ostree = rootfs_dir.try_exists("ostree/repo")?;
if !has_ostree {
Task::new_and_run(
"Initializing ostree layout",
"ostree",
["admin", "init-fs", "--modern", rootfs.as_str()],
)?;
} else {
println!("Reusing extant ostree layout");
let _ = crate::utils::open_dir_remount_rw(rootfs_dir, "sysroot".into())?;
}

// Default to avoiding grub2-mkconfig etc., but we need to use zipl on s390x.
// TODO: Lower this logic into ostree proper.
Expand All @@ -482,10 +488,15 @@ async fn initialize_ostree_root_from_self(
.quiet()
.run()?;
}
Task::new("Initializing sysroot", "ostree")
.args(["admin", "os-init", stateroot, "--sysroot", "."])
.cwd(rootfs_dir)?
.run()?;
let stateroot_exists = rootfs_dir.try_exists(format!("ostree/deploy/{stateroot}"))?;
if stateroot_exists {
anyhow::bail!("Cannot redeploy over extant stateroot {stateroot}");
} else {
Task::new("Initializing sysroot", "ostree")
.args(["admin", "os-init", stateroot, "--sysroot", "."])
.cwd(rootfs_dir)?
.run()?;
}

// Ensure everything in the ostree repo is labeled
state.lsm_label(&rootfs.join("ostree"), "/usr".into(), true)?;
Expand Down Expand Up @@ -532,6 +543,7 @@ async fn initialize_ostree_root_from_self(
options.kargs = Some(kargs.as_slice());
options.target_imgref = Some(&target_imgref);
options.proxy_cfg = Some(proxy_cfg);
options.no_clean = has_ostree;
println!("Creating initial deployment");
let state =
ostree_container::deploy::deploy(&sysroot, stateroot, &src_imageref, Some(options)).await?;
Expand Down Expand Up @@ -845,6 +857,18 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
}

let boot_uuid = rootfs.get_boot_uuid()?;
// If we're doing an alongside install, then the /dev bootupd sees needs to be the host's.
// What we probably really want to do here is tunnel in the host's /dev properly, but for now
// just copy /dev/disk
if rootfs.skip_finalize {
if !Utf8Path::new("/dev/disk").try_exists()? {
Task::new_and_run(
"Copying host /dev/disk",
"cp",
["-a", "/proc/1/root/dev/disk", "/dev/disk"],
)?;
}
}
crate::bootloader::install_via_bootupd(&rootfs.device, &rootfs.rootfs, boot_uuid)?;
tracing::debug!("Installed bootloader");

Expand Down Expand Up @@ -958,7 +982,8 @@ fn remove_all_in_dir_no_xdev(d: &Dir) -> Result<()> {

#[context("Removing boot directory content")]
fn clean_boot_directories(rootfs: &Dir) -> Result<()> {
let bootdir = rootfs.open_dir(BOOT).context("Opening /boot")?;
let bootdir =
crate::utils::open_dir_remount_rw(rootfs, BOOT.into()).context("Opening /boot")?;
// This should not remove /boot/efi note.
remove_all_in_dir_no_xdev(&bootdir)?;
if ARCH_USES_EFI {
Expand Down
42 changes: 42 additions & 0 deletions lib/src/utils.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,12 @@ use std::os::unix::prelude::OsStringExt;
use std::process::Command;

use anyhow::{Context, Result};
use camino::Utf8Path;
use cap_std_ext::{cap_std::fs::Dir, prelude::CapStdExtCommandExt};
use fn_error_context::context;
use ostree::glib;
use ostree_ext::ostree;
use std::os::fd::AsFd;

/// Try to look for keys injected by e.g. rpm-ostree requesting machine-local
/// changes; if any are present, return `true`.
Expand Down Expand Up @@ -32,6 +36,44 @@ pub(crate) fn find_mount_option<'a>(
.next()
}

/// Try to (heuristically) determine if the provided path is a mount root.
pub(crate) fn is_mountpoint(root: &Dir, path: &Utf8Path) -> Result<Option<bool>> {
// https://github.com/systemd/systemd/blob/8fbf0a214e2fe474655b17a4b663122943b55db0/src/basic/mountpoint-util.c#L176
use rustix::fs::{AtFlags, StatxFlags};

// SAFETY(unwrap): We can infallibly convert an i32 into a u64.
let mountroot_flag: u64 = libc::STATX_ATTR_MOUNT_ROOT.try_into().unwrap();
match rustix::fs::statx(
root.as_fd(),
path.as_std_path(),
AtFlags::NO_AUTOMOUNT | AtFlags::SYMLINK_NOFOLLOW,
StatxFlags::empty(),
) {
Ok(r) => {
let present = (r.stx_attributes_mask & mountroot_flag) > 0;
Ok(present.then(|| r.stx_attributes & mountroot_flag > 0))
}
Err(e) if e == rustix::io::Errno::NOSYS => Ok(None),
Err(e) => Err(e.into()),
}
}

/// Given a target directory, if it's a read-only mount, then remount it writable
#[context("Opening {target} with writable mount")]
pub(crate) fn open_dir_remount_rw(root: &Dir, target: &Utf8Path) -> Result<Dir> {
if is_mountpoint(root, target)?.unwrap_or_default() {
tracing::debug!("Target {target} is a mountpoint, remounting rw");
let st = Command::new("mount")
.args(["-o", "remount,rw", target.as_str()])
.cwd_dir(root.try_clone()?)
.status()?;
if !st.success() {
anyhow::bail!("Failed to remount: {st:?}");
}
}
root.open_dir(target).map_err(anyhow::Error::new)
}

/// Run a command in the host mount namespace
#[allow(dead_code)]
pub(crate) fn run_in_host_mountns(cmd: &str) -> Command {
Expand Down

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