lib: Remove composefs-backend feature gate

While composefs is still experimental, after looking at this
I think the feature gating we're doing has a pretty high "pain:gain"
ratio - in other words, the risk we're mitigating by having it
off is very low.

Since composefs is a focus of development, let's just remove
the feature gate. We have good CI coverage for the non-composefs
case.

Assisted-by: Claude Code (Sonnet 4.5)
Signed-off-by: Colin Walters <walters@verbum.org>

crates/lib/Cargo.toml

@@ -74,13 +74,11 @@ similar-asserts = { workspace = true }
 static_assertions = { workspace = true }
 
 [features]
-default = ["install-to-disk", "composefs-backend"]
+default = ["install-to-disk"]
 # This feature enables `bootc install to-disk`, which is considered just a "demo"
 # or reference installer; we expect most nontrivial use cases to be using
 # `bootc install to-filesystem`.
 install-to-disk = []
-# Enable support for the composefs native backend
-composefs-backend = []
 # This featuares enables `bootc internals publish-rhsm-facts` to integrate with
 # Red Hat Subscription Manager
 rhsm = []

crates/lib/src/bootloader.rs

@@ -8,7 +8,6 @@ use fn_error_context::context;
 use bootc_blockdev::{Partition, PartitionTable};
 use bootc_mount as mount;
 
-#[cfg(any(feature = "composefs-backend", feature = "install-to-disk"))]
 use crate::bootc_composefs::boot::mount_esp;
 use crate::{discoverable_partition_specification, utils};
 
@@ -72,7 +71,6 @@ pub(crate) fn install_via_bootupd(
 }
 
 #[context("Installing bootloader")]
-#[cfg(any(feature = "composefs-backend", feature = "install-to-disk"))]
 pub(crate) fn install_systemd_boot(
     device: &PartitionTable,
     _rootfs: &Utf8Path,

crates/lib/src/cli.rs

@@ -33,7 +33,6 @@ use schemars::schema_for;
 use serde::{Deserialize, Serialize};
 use tempfile::tempdir_in;
 
-#[cfg(feature = "composefs-backend")]
 use crate::bootc_composefs::{
     finalize::{composefs_backend_finalize, get_etc_diff},
     rollback::composefs_rollback,
@@ -667,9 +666,7 @@ pub(crate) enum Opt {
     #[clap(subcommand)]
     #[clap(hide = true)]
     Internals(InternalsOpts),
-    #[cfg(feature = "composefs-backend")]
     ComposefsFinalizeStaged,
-    #[cfg(feature = "composefs-backend")]
     /// Diff current /etc configuration versus default
     ConfigDiff,
 }
@@ -1263,38 +1260,26 @@ async fn run_from_opt(opt: Opt) -> Result<()> {
     let root = &Dir::open_ambient_dir("/", cap_std::ambient_authority())?;
     match opt {
         Opt::Upgrade(opts) => {
-            #[cfg(feature = "composefs-backend")]
             if composefs_booted()?.is_some() {
                 upgrade_composefs(opts).await
             } else {
                 upgrade(opts).await
             }
-
-            #[cfg(not(feature = "composefs-backend"))]
-            upgrade(opts).await
         }
         Opt::Switch(opts) => {
-            #[cfg(feature = "composefs-backend")]
             if composefs_booted()?.is_some() {
                 switch_composefs(opts).await
             } else {
                 switch(opts).await
             }
-
-            #[cfg(not(feature = "composefs-backend"))]
-            switch(opts).await
         }
         Opt::Rollback(opts) => {
-            #[cfg(feature = "composefs-backend")]
             if composefs_booted()?.is_some() {
                 composefs_rollback().await?
             } else {
                 rollback(&opts).await?
             }
 
-            #[cfg(not(feature = "composefs-backend"))]
-            rollback(&opts).await?;
-
             if opts.apply {
                 crate::reboot::reboot()?;
             }
@@ -1303,15 +1288,11 @@ async fn run_from_opt(opt: Opt) -> Result<()> {
         }
         Opt::Edit(opts) => edit(opts).await,
         Opt::UsrOverlay => {
-            #[cfg(feature = "composefs-backend")]
             if composefs_booted()?.is_some() {
                 composefs_usr_overlay()
             } else {
                 usroverlay().await
             }
-
-            #[cfg(not(feature = "composefs-backend"))]
-            usroverlay().await
         }
         Opt::Container(opts) => match opts {
             ContainerOpts::Lint {
@@ -1604,10 +1585,8 @@ async fn run_from_opt(opt: Opt) -> Result<()> {
             }
         },
 
-        #[cfg(feature = "composefs-backend")]
         Opt::ComposefsFinalizeStaged => composefs_backend_finalize().await,
 
-        #[cfg(feature = "composefs-backend")]
         Opt::ConfigDiff => get_etc_diff().await,
     }
 }

crates/lib/src/install.rs

@@ -53,7 +53,6 @@ use serde::{Deserialize, Serialize};
 
 #[cfg(feature = "install-to-disk")]
 use self::baseline::InstallBlockDeviceOpts;
-#[cfg(feature = "composefs-backend")]
 use crate::bootc_composefs::{boot::setup_composefs_boot, repo::initialize_composefs_repository};
 use crate::boundimage::{BoundImage, ResolvedBoundImage};
 use crate::containerenv::ContainerExecutionInfo;
@@ -66,7 +65,6 @@ use crate::task::Task;
 use crate::utils::sigpolicy_from_opt;
 use bootc_kernel_cmdline::{bytes, utf8, INITRD_ARG_PREFIX, ROOTFLAGS};
 use bootc_mount::Filesystem;
-#[cfg(feature = "composefs-backend")]
 use composefs::fsverity::FsVerityHashValue;
 
 /// The toplevel boot directory
@@ -275,7 +273,6 @@ pub(crate) struct InstallToDiskOpts {
 
     #[clap(flatten)]
     #[serde(flatten)]
-    #[cfg(feature = "composefs-backend")]
     pub(crate) composefs_opts: InstallComposefsOpts,
 }
 
@@ -353,7 +350,6 @@ pub(crate) struct InstallToFilesystemOpts {
     #[clap(flatten)]
     pub(crate) config_opts: InstallConfigOpts,
 
-    #[cfg(feature = "composefs-backend")]
     #[clap(flatten)]
     pub(crate) composefs_opts: InstallComposefsOpts,
 }
@@ -388,7 +384,6 @@ pub(crate) struct InstallToExistingRootOpts {
     #[clap(default_value = ALONGSIDE_ROOT_MOUNT)]
     pub(crate) root_path: Utf8PathBuf,
 
-    #[cfg(feature = "composefs-backend")]
     #[clap(flatten)]
     pub(crate) composefs_opts: InstallComposefsOpts,
 }
@@ -431,7 +426,6 @@ pub(crate) struct State {
     pub(crate) composefs_required: bool,
 
     // If Some, then --composefs_native is passed
-    #[cfg(feature = "composefs-backend")]
     pub(crate) composefs_options: InstallComposefsOpts,
 
     /// Detected bootloader type for the target system
@@ -562,7 +556,7 @@ impl FromStr for MountSpec {
     }
 }
 
-#[cfg(all(feature = "install-to-disk", feature = "composefs-backend"))]
+#[cfg(feature = "install-to-disk")]
 impl InstallToDiskOpts {
     pub(crate) fn validate(&self) -> Result<()> {
         if !self.composefs_opts.composefs_backend {
@@ -1218,11 +1212,7 @@ async fn verify_target_fetch(
 }
 
 fn root_has_uki(root: &Dir) -> Result<bool> {
-    #[cfg(feature = "composefs-backend")]
-    return crate::bootc_composefs::boot::container_root_has_uki(root);
-
-    #[cfg(not(feature = "composefs-backend"))]
-    Ok(false)
+    crate::bootc_composefs::boot::container_root_has_uki(root)
 }
 
 /// Preparation for an install; validates and prepares some (thereafter immutable) global state.
@@ -1230,7 +1220,7 @@ async fn prepare_install(
     config_opts: InstallConfigOpts,
     source_opts: InstallSourceOpts,
     target_opts: InstallTargetOpts,
-    #[cfg(feature = "composefs-backend")] mut composefs_options: InstallComposefsOpts,
+    mut composefs_options: InstallComposefsOpts,
 ) -> Result<Arc<State>> {
     tracing::trace!("Preparing install");
     let rootfs = cap_std::fs::Dir::open_ambient_dir("/", cap_std::ambient_authority())
@@ -1305,7 +1295,6 @@ async fn prepare_install(
 
     tracing::debug!("Composefs required: {composefs_required}");
 
-    #[cfg(feature = "composefs-backend")]
     if composefs_required {
         composefs_options.composefs_backend = true;
     }
@@ -1378,7 +1367,6 @@ async fn prepare_install(
 
     // Determine bootloader type for the target system
     // Priority: user-specified > bootupd availability > systemd-boot fallback
-    #[cfg(feature = "composefs-backend")]
     let detected_bootloader = {
         if let Some(bootloader) = composefs_options.bootloader.clone() {
             bootloader
@@ -1390,8 +1378,6 @@ async fn prepare_install(
             }
         }
     };
-    #[cfg(not(feature = "composefs-backend"))]
-    let detected_bootloader = crate::spec::Bootloader::Grub;
     println!("Bootloader: {detected_bootloader}");
 
     // Create our global (read-only) state which gets wrapped in an Arc
@@ -1410,7 +1396,6 @@ async fn prepare_install(
         host_is_container,
         composefs_required,
         detected_bootloader,
-        #[cfg(feature = "composefs-backend")]
         composefs_options,
     });
 
@@ -1582,7 +1567,6 @@ async fn install_to_filesystem_impl(
         }
     }
 
-    #[cfg(feature = "composefs-backend")]
     if state.composefs_options.composefs_backend {
         // Load a fd for the mounted target physical root
 
@@ -1593,9 +1577,6 @@ async fn install_to_filesystem_impl(
         ostree_install(state, rootfs, cleanup).await?;
     }
 
-    #[cfg(not(feature = "composefs-backend"))]
-    ostree_install(state, rootfs, cleanup).await?;
-
     // Finalize mounted filesystems
     if !rootfs.skip_finalize {
         let bootfs = rootfs.boot.as_ref().map(|_| ("boot", "boot"));
@@ -1615,7 +1596,6 @@ fn installation_complete() {
 #[context("Installing to disk")]
 #[cfg(feature = "install-to-disk")]
 pub(crate) async fn install_to_disk(mut opts: InstallToDiskOpts) -> Result<()> {
-    #[cfg(feature = "composefs-backend")]
     opts.validate()?;
 
     // Log the disk installation operation to systemd journal
@@ -1664,7 +1644,6 @@ pub(crate) async fn install_to_disk(mut opts: InstallToDiskOpts) -> Result<()> {
         opts.config_opts,
         opts.source_opts,
         opts.target_opts,
-        #[cfg(feature = "composefs-backend")]
         opts.composefs_opts,
     )
     .await?;
@@ -1902,7 +1881,6 @@ pub(crate) async fn install_to_filesystem(
         opts.config_opts,
         opts.source_opts,
         opts.target_opts,
-        #[cfg(feature = "composefs-backend")]
         opts.composefs_opts,
     )
     .await?;
@@ -2174,7 +2152,6 @@ pub(crate) async fn install_to_existing_root(opts: InstallToExistingRootOpts) ->
         source_opts: opts.source_opts,
         target_opts: opts.target_opts,
         config_opts: opts.config_opts,
-        #[cfg(feature = "composefs-backend")]
         composefs_opts: opts.composefs_opts,
     };
 

crates/lib/src/lib.rs

@@ -4,7 +4,6 @@
 //! to provide a fully "container native" tool for using
 //! bootable container images.
 
-#[cfg(feature = "composefs-backend")]
 mod bootc_composefs;
 pub(crate) mod bootc_kargs;
 mod bootloader;

crates/lib/src/lints.rs

@@ -27,7 +27,6 @@ use linkme::distributed_slice;
 use ostree_ext::ostree_prepareroot;
 use serde::Serialize;
 
-#[cfg(feature = "composefs-backend")]
 use crate::bootc_composefs::boot::EFI_LINUX;
 
 /// Reference to embedded default baseimage content that should exist.
@@ -770,7 +769,6 @@ fn check_boot(root: &Dir, config: &LintExecutionConfig) -> LintResult {
         })
         .collect();
     let mut entries = entries?;
-    #[cfg(feature = "composefs-backend")]
     {
         // Work around https://github.com/containers/composefs-rs/issues/131
         let efidir = Utf8Path::new(EFI_LINUX)

crates/lib/src/spec.rs

@@ -11,7 +11,6 @@ use ostree_ext::{container::OstreeImageReference, oci_spec};
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 
-#[cfg(feature = "composefs-backend")]
 use crate::bootc_composefs::boot::BootType;
 use crate::{k8sapitypes, status::Slot};
 
@@ -201,7 +200,6 @@ impl FromStr for Bootloader {
 /// A bootable entry
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, JsonSchema)]
 #[serde(rename_all = "camelCase")]
-#[cfg(feature = "composefs-backend")]
 pub struct BootEntryComposefs {
     /// The erofs verity
     pub verity: String,
@@ -232,7 +230,6 @@ pub struct BootEntry {
     /// If this boot entry is ostree based, the corresponding state
     pub ostree: Option<BootEntryOstree>,
     /// If this boot entry is composefs based, the corresponding state
-    #[cfg(feature = "composefs-backend")]
     pub composefs: Option<BootEntryComposefs>,
 }
 
@@ -305,7 +302,6 @@ impl Host {
         }
     }
 
-    #[cfg(feature = "composefs-backend")]
     pub(crate) fn require_composefs_booted(&self) -> anyhow::Result<&BootEntryComposefs> {
         let cfs = self
             .status
@@ -588,7 +584,6 @@ mod tests {
                 pinned: false,
                 store: None,
                 ostree: None,
-                #[cfg(feature = "composefs-backend")]
                 composefs: None,
             }
         }

crates/lib/src/status.rs

@@ -19,7 +19,6 @@ use ostree_ext::sysroot::SysrootLock;
 
 use ostree_ext::ostree;
 
-#[cfg(feature = "composefs-backend")]
 use crate::bootc_composefs::status::{composefs_booted, composefs_deployment_status};
 use crate::cli::OutputFormat;
 use crate::spec::ImageStatus;
@@ -210,7 +209,6 @@ fn boot_entry_from_deployment(
             deploy_serial: deployment.deployserial().try_into().unwrap(),
             stateroot: deployment.stateroot().into(),
         }),
-        #[cfg(feature = "composefs-backend")]
         composefs: None,
     };
     Ok(r)
@@ -340,7 +338,6 @@ pub(crate) fn get_status(
     Ok((deployments, host))
 }
 
-#[cfg(feature = "composefs-backend")]
 async fn get_host() -> Result<Host> {
     let host = if ostree_booted()? {
         let sysroot = super::cli::get_storage().await?;
@@ -357,21 +354,6 @@ async fn get_host() -> Result<Host> {
     Ok(host)
 }
 
-#[cfg(not(feature = "composefs-backend"))]
-async fn get_host() -> Result<Host> {
-    let host = if ostree_booted()? {
-        let sysroot = super::cli::get_storage().await?;
-        let ostree = sysroot.get_ostree()?;
-        let booted_deployment = ostree.booted_deployment();
-        let (_deployments, host) = get_status(&ostree, booted_deployment.as_ref())?;
-        host
-    } else {
-        Default::default()
-    };
-
-    Ok(host)
-}
-
 /// Implementation of the `bootc status` CLI command.
 #[context("Status")]
 pub(crate) async fn status(opts: super::cli::StatusOpts) -> Result<()> {
@@ -515,7 +497,6 @@ fn human_render_slot(
     writeln!(out, "{digest} ({arch})")?;
 
     // Write the EROFS verity if present
-    #[cfg(feature = "composefs-backend")]
     if let Some(composefs) = &entry.composefs {
         write_row_name(&mut out, "Verity", prefix_len)?;
         writeln!(out, "{}", composefs.verity)?;
@@ -622,7 +603,6 @@ fn human_render_slot_ostree(
 }
 
 /// Output a rendering of a non-container composefs boot entry.
-#[cfg(feature = "composefs-backend")]
 fn human_render_slot_composefs(
     mut out: impl Write,
     slot: Slot,
@@ -657,7 +637,6 @@ fn human_readable_output_booted(mut out: impl Write, host: &Host, verbose: bool)
                 writeln!(out)?;
             }
 
-            #[cfg(feature = "composefs-backend")]
             if let Some(image) = &host_status.image {
                 human_render_slot(&mut out, Some(slot_name), host_status, image, verbose)?;
             } else if let Some(ostree) = host_status.ostree.as_ref() {
@@ -673,21 +652,6 @@ fn human_readable_output_booted(mut out: impl Write, host: &Host, verbose: bool)
             } else {
                 writeln!(out, "Current {slot_name} state is unknown")?;
             }
-
-            #[cfg(not(feature = "composefs-backend"))]
-            if let Some(image) = &host_status.image {
-                human_render_slot(&mut out, Some(slot_name), host_status, image, verbose)?;
-            } else if let Some(ostree) = host_status.ostree.as_ref() {
-                human_render_slot_ostree(
-                    &mut out,
-                    Some(slot_name),
-                    host_status,
-                    &ostree.checksum,
-                    verbose,
-                )?;
-            } else {
-                writeln!(out, "Current {slot_name} state is unknown")?;
-            }
         }
     }
 

crates/lib/src/store/mod.rs

@@ -37,7 +37,6 @@ use crate::utils::deployment_fd;
 /// See https://github.com/containers/composefs-rs/issues/159
 pub type ComposefsRepository =
     composefs::repository::Repository<composefs::fsverity::Sha512HashValue>;
-#[cfg(feature = "composefs-backend")]
 pub type ComposefsFilesystem = composefs::tree::FileSystem<composefs::fsverity::Sha512HashValue>;
 
 /// Path to the physical root

crates/lib/src/utils.rs

@@ -1,7 +1,6 @@
 use std::future::Future;
 use std::io::Write;
 use std::os::fd::BorrowedFd;
-#[cfg(feature = "composefs-backend")]
 use std::path::{Component, Path, PathBuf};
 use std::process::Command;
 use std::time::Duration;
@@ -202,7 +201,6 @@ pub(crate) fn digested_pullspec(image: &str, digest: &str) -> String {
     format!("{image}@{digest}")
 }
 
-#[cfg(feature = "composefs-backend")]
 #[derive(Debug)]
 pub enum EfiError {
     SystemNotUEFI,
@@ -213,14 +211,12 @@ pub enum EfiError {
     Io(std::io::Error),
 }
 
-#[cfg(feature = "composefs-backend")]
 impl From<std::io::Error> for EfiError {
     fn from(e: std::io::Error) -> Self {
         EfiError::Io(e)
     }
 }
 
-#[cfg(feature = "composefs-backend")]
 pub fn read_uefi_var(var_name: &str) -> Result<String, EfiError> {
     use crate::install::EFIVARFS;
     use cap_std_ext::cap_std::ambient_authority;
@@ -262,7 +258,6 @@ pub fn read_uefi_var(var_name: &str) -> Result<String, EfiError> {
 /// Computes a relative path from `from` to `to`.
 ///
 /// Both `from` and `to` must be absolute paths.
-#[cfg(feature = "composefs-backend")]
 pub(crate) fn path_relative_to(from: &Path, to: &Path) -> Result<PathBuf> {
     if !from.is_absolute() || !to.is_absolute() {
         anyhow::bail!("Paths must be absolute");
@@ -321,7 +316,6 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "composefs-backend")]
     fn test_relative_path() {
         let from = Path::new("/sysroot/state/deploy/image_id");
         let to = Path::new("/sysroot/state/os/default/var");

docs/src/experimental-composefs.md

@@ -9,7 +9,7 @@ Tracking issue: <https://github.com/bootc-dev/bootc/issues/1190>
 
 The composefs backend is an experimental alternative storage backend that uses [composefs-rs](https://github.com/containers/composefs-rs) instead of ostree for storing and managing bootc system deployments.
 
-**Status**: Experimental. The composefs backend is under active development and not yet suitable for production use. The feature is currently gated behind the `composefs-backend` compile-time feature flag, which in current git main is enabled by default.
+**Status**: Experimental. The composefs backend is under active development and not yet suitable for production use. The feature is always compiled in as of bootc v1.10.1.
 
 ## Key Benefits