Add support for --remove-installed-kernel

Closes: #2542

Today anyone wanting to switch to a different kernel variant
such as `kernel-rt` must manually pass all the *current* kernel
packages to `--uninstall` (separately).  It's not just very unergonomic,
it also makes the calling code *operating system dependent* because
as just happened when C9S added a `kernel-modules-core` package,
that suddenly also needs to be specified.

xref https://issues.redhat.com/browse/OCPBUGS-8113

ci/test-container.sh

@@ -116,6 +116,14 @@ rpm -q ignition
 dnf -y uninstall kexec-tools
 if rpm -q kexec-tools; then fatal "failed to remove kexec-tools"; fi
 
+rpm -q kernel
+# Fedora doesn't ship kernel variants, so we just install some other package
+rpm-ostree install --remove-installed-kernel strace
+if rpm -qa |grep -E '^kernel'; then
+  fatal "Found installed kernel after --remove-installed-kernel"
+fi
+rpm -e strace
+
 # test replacement by Koji URL
 rpm-ostree override replace $koji_url |& tee out.txt
 n_downloaded=$(grep Downloading out.txt | wc -l)

rpmostree-cxxrs.cxx

@@ -1703,6 +1703,8 @@ struct Treefile final : public ::rust::Opaque
   bool remove_package_override_remove (::rust::Str package) noexcept;
   bool has_packages_override_remove_name (::rust::Str name) const noexcept;
   bool remove_all_overrides () noexcept;
+  bool has_remove_kernel () const noexcept;
+  bool set_remove_kernel (bool remove) noexcept;
   ::rust::Vec< ::rust::String> get_modules_enable () const noexcept;
   bool has_modules_enable () const noexcept;
   ::rust::Vec< ::rust::String> get_modules_install () const noexcept;
@@ -2487,6 +2489,12 @@ extern "C"
   bool
   rpmostreecxx$cxxbridge1$Treefile$remove_all_overrides (::rpmostreecxx::Treefile &self) noexcept;
 
+  bool rpmostreecxx$cxxbridge1$Treefile$has_remove_kernel (
+      const ::rpmostreecxx::Treefile &self) noexcept;
+
+  bool rpmostreecxx$cxxbridge1$Treefile$set_remove_kernel (::rpmostreecxx::Treefile &self,
+                                                           bool remove) noexcept;
+
   void rpmostreecxx$cxxbridge1$Treefile$get_modules_enable (
       const ::rpmostreecxx::Treefile &self, ::rust::Vec< ::rust::String> *return$) noexcept;
 
@@ -4902,6 +4910,18 @@ Treefile::remove_all_overrides () noexcept
   return rpmostreecxx$cxxbridge1$Treefile$remove_all_overrides (*this);
 }
 
+bool
+Treefile::has_remove_kernel () const noexcept
+{
+  return rpmostreecxx$cxxbridge1$Treefile$has_remove_kernel (*this);
+}
+
+bool
+Treefile::set_remove_kernel (bool remove) noexcept
+{
+  return rpmostreecxx$cxxbridge1$Treefile$set_remove_kernel (*this, remove);
+}
+
 ::rust::Vec< ::rust::String>
 Treefile::get_modules_enable () const noexcept
 {

rpmostree-cxxrs.h

@@ -1485,6 +1485,8 @@ struct Treefile final : public ::rust::Opaque
   bool remove_package_override_remove (::rust::Str package) noexcept;
   bool has_packages_override_remove_name (::rust::Str name) const noexcept;
   bool remove_all_overrides () noexcept;
+  bool has_remove_kernel () const noexcept;
+  bool set_remove_kernel (bool remove) noexcept;
   ::rust::Vec< ::rust::String> get_modules_enable () const noexcept;
   bool has_modules_enable () const noexcept;
   ::rust::Vec< ::rust::String> get_modules_install () const noexcept;

rust/src/lib.rs

@@ -560,6 +560,8 @@ pub mod ffi {
         fn remove_package_override_remove(&mut self, package: &str) -> bool;
         fn has_packages_override_remove_name(&self, name: &str) -> bool;
         fn remove_all_overrides(&mut self) -> bool;
+        fn has_remove_kernel(&self) -> bool;
+        fn set_remove_kernel(&mut self, remove: bool) -> bool;
         fn get_modules_enable(&self) -> Vec<String>;
         fn has_modules_enable(&self) -> bool;
         fn get_modules_install(&self) -> Vec<String>;

rust/src/treefile.rs

@@ -486,6 +486,10 @@ fn treefile_merge(dest: &mut TreeComposeConfig, src: &mut TreeComposeConfig) {
         &mut dest.derive.override_replace,
         &mut src.derive.override_replace,
     );
+    merge_basic_field(
+        &mut dest.derive.override_remove_kernel,
+        &mut src.derive.override_remove_kernel,
+    );
     dest.handle_repo_packages_override_replacements();
     merge_map_field(
         &mut dest.derive.override_replace_local,
@@ -1040,6 +1044,15 @@ impl Treefile {
             .unwrap_or_default()
     }
 
+    /// Kernel removal is configured
+    pub(crate) fn has_remove_kernel(&self) -> bool {
+        self.parsed
+            .derive
+            .override_remove_kernel
+            .clone()
+            .unwrap_or_default()
+    }
+
     // Check that the same overrides don't already exist. Of course, in the local replace
     // case, this doesn't catch same pkg name but different EVRA; we'll just barf at that
     // later on in the core. This is an early easy sanity check.
@@ -1135,6 +1148,21 @@ impl Treefile {
         Some(old_map) != self.parsed.derive.override_replace
     }
 
+    /// Change the state of kernel removal for derived images
+    pub(crate) fn set_remove_kernel(&mut self, remove: bool) -> bool {
+        let current = self
+            .parsed
+            .derive
+            .override_remove_kernel
+            .take()
+            .unwrap_or_default();
+        // Note we did .take() above, so this also canonicalizes false -> None
+        if remove {
+            self.parsed.derive.override_remove_kernel = Some(true);
+        }
+        current != remove
+    }
+
     pub(crate) fn remove_package_override_replace(&mut self, package: &str) -> bool {
         self.parsed
             .derive
@@ -1196,6 +1224,7 @@ impl Treefile {
             .map(|x| !x.is_empty())
             .unwrap_or_default()
             || changed;
+        changed = self.set_remove_kernel(false) || changed;
         changed
     }
 
@@ -1621,6 +1650,7 @@ impl Treefile {
         clone.override_replace.take();
         clone.override_remove.take();
         clone.override_replace_local.take();
+        clone.override_remove_kernel.take();
         if clone != Default::default() {
             let j = serde_json::to_string_pretty(&clone)?;
             bail!(
@@ -1894,6 +1924,12 @@ impl Treefile {
                 .as_ref()
                 .and_then(|m| m.install.as_ref().map(|i| !i.is_empty()))
                 .unwrap_or_default()
+            || self
+                .parsed
+                .derive
+                .override_remove_kernel
+                .clone()
+                .unwrap_or_default()
     }
 
     /// Derive RPM importer flags for a given package and treefile settings.
@@ -2714,6 +2750,9 @@ pub(crate) struct DeriveConfigFields {
     pub(crate) packages_local_fileoverride: Option<BTreeMap<String, String>>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(crate) override_remove: Option<BTreeSet<String>>,
+    /// Remove the kernel
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(crate) override_remove_kernel: Option<bool>,
     #[serde(rename = "ex-override-replace")]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(crate) override_replace: Option<Vec<RemoteOverrideReplace>>,

src/app/rpmostree-pkg-builtins.cxx

@@ -38,6 +38,7 @@ static gboolean opt_apply_live;
 static gboolean opt_idempotent;
 static gchar **opt_install;
 static gboolean opt_assumeyes;
+static gboolean opt_remove_kernel;
 static gchar **opt_uninstall;
 static gboolean opt_cache_only;
 static gboolean opt_download_only;
@@ -90,6 +91,9 @@ static GOptionEntry install_option_entry[]
           "Just download latest ostree and RPM data, don't deploy", NULL },
         { "apply-live", 'A', 0, G_OPTION_ARG_NONE, &opt_apply_live,
           "Apply changes to both pending deployment and running filesystem tree", NULL },
+        { "remove-installed-kernel", 0, 0, G_OPTION_ARG_NONE, &opt_remove_kernel,
+          "Remove the installed kernel packages (usually helpful to install a different kernel)",
+          NULL },
         { "force-replacefiles", 0, 0, G_OPTION_ARG_NONE, &opt_force_replacefiles,
           "Allow package to replace files from other packages", NULL },
         { NULL } };
@@ -260,6 +264,8 @@ rpmostree_builtin_install (int argc, char **argv, RpmOstreeCommandInvocation *in
           auto ver = rust::Str (*it);
           treefile->set_releasever (ver);
         }
+      if (opt_remove_kernel)
+        treefile->set_remove_kernel (true);
       return rpmostree_container_rebuild (*treefile, cancellable, error);
     }
 

src/libpriv/rpmostree-core.cxx

@@ -54,6 +54,15 @@
 #define RPMOSTREE_MESSAGE_PKG_IMPORT                                                               \
   SD_ID128_MAKE (df, 8b, b5, 4f, 04, fa, 47, 08, ac, 16, 11, 1b, bf, 4b, a3, 52)
 
+// This is a copy of the defaults from libdnf because it's not public API
+// see INSTALLONLYPKGS there.
+static const char *KERNEL_PACKAGES[] = { "kernel",
+                                         "kernel-PAE",
+                                         "installonlypkg(kernel)",
+                                         "installonlypkg(kernel-module)",
+                                         "installonlypkg(vm)",
+                                         "multiversion(kernel)" };
+
 static OstreeRepo *get_pkgcache_repo (RpmOstreeContext *self);
 
 static int
@@ -1734,6 +1743,7 @@ rpmostree_context_prepare (RpmOstreeContext *self, GCancellable *cancellable, GE
   auto exclude_packages = self->treefile_rs->get_exclude_packages ();
   auto modules_enable = self->treefile_rs->get_modules_enable ();
   auto modules_install = self->treefile_rs->get_modules_install ();
+  auto remove_kernel = self->treefile_rs->has_remove_kernel ();
 
   /* we only support pure installs for now (compose case) */
   if (self->lockfile)
@@ -1945,6 +1955,25 @@ rpmostree_context_prepare (RpmOstreeContext *self, GCancellable *cancellable, GE
       g_ptr_array_add (removed_pkgnames, (gpointer)pkgname);
     }
 
+  if (remove_kernel)
+    {
+      for (guint i = 0; i < G_N_ELEMENTS (KERNEL_PACKAGES); i++)
+        {
+          const char *pkg = KERNEL_PACKAGES[i];
+          hy_autoquery HyQuery query = hy_query_create (sack);
+          hy_query_filter (query, HY_PKG_REPONAME, HY_EQ, HY_SYSTEM_REPO_NAME);
+          hy_query_filter (query, HY_PKG_PROVIDES, HY_EQ, pkg);
+          g_autoptr (GPtrArray) packages = hy_query_run (query);
+          for (guint i = 0; i < packages->len; i++)
+            {
+              auto pkg = static_cast<DnfPackage *> (g_ptr_array_index (packages, i));
+              g_printerr ("Removing kernel pkg: %s\n", dnf_package_get_name (pkg));
+              g_ptr_array_add (removed_pkgnames, (gpointer)dnf_package_get_name (pkg));
+              hy_goal_erase (goal, pkg);
+            }
+        }
+    }
+
   /* Then, handle local packages to install */
   GLNX_HASH_TABLE_FOREACH_V (local_pkgs_to_install, DnfPackage *, pkg)
     hy_goal_install (goal, pkg);