Add rpm-ostree ex rebuild command

This command reads treefile dropins in `/etc` and applies it to the
system. Only the OSTree container flow is supported for now. For the
client-side flow, see coreos#2326.

In the container flow, only `packages` is currently supported. But this
paves the way for supporting more derivation fields as well as making
currently "base" fields only become valid derivation fields too (by
promoting it from the `BaseComposeConfigFields` struct to
`TreeComposeConfig`).

What we're doing here is providing a "container" backend for derivation
treefiles, but coreos#2326 will provide a "client" backend which uses the core
more fully. But the inputs themselves are the exact same, hence
providing symmetry between the two flows. (See also discussions about
this in coreos/fedora-coreos-tracker#1054).

This will also allow us to drop the `microdnf` dependency which will be
done in a following patch.

Makefile-libpriv.am

@@ -25,6 +25,8 @@ librpmostreepriv_sources = \
 	src/libpriv/rpmostree-types.h \
 	src/libpriv/rpmostree-refts.h \
 	src/libpriv/rpmostree-refts.cxx \
+	src/libpriv/rpmostree-container.cxx \
+	src/libpriv/rpmostree-container.h \
 	src/libpriv/rpmostree-core.cxx \
 	src/libpriv/rpmostree-core.h \
 	src/libpriv/rpmostree-core-private.h \

Makefile-rpm-ostree.am

@@ -59,6 +59,7 @@ librpmostreeinternals_la_SOURCES = \
 	src/app/rpmostree-composeutil.cxx \
 	src/app/rpmostree-composeutil.h \
 	src/app/rpmostree-builtin-compose.cxx \
+	src/app/rpmostree-builtin-rebuild.cxx \
 	$(librpmostreed_sources) \
 	$(librpmostreepriv_sources) \
 	$(librpmostree_1_la_SOURCES) \

rust/src/lib.rs

@@ -393,6 +393,7 @@ pub mod ffi {
         ) -> Result<Box<Treefile>>;
         fn treefile_new_client(filename: &str, basearch: &str) -> Result<Box<Treefile>>;
         fn treefile_new_client_from_etc(basearch: &str) -> Result<Box<Treefile>>;
+        fn treefile_delete_client_etc() -> Result<()>;
 
         fn get_workdir(&self) -> i32;
         fn get_passwd_fd(&mut self) -> i32;

rust/src/treefile.rs

@@ -2289,3 +2289,12 @@ pub(crate) fn treefile_new_client_from_etc(basearch: &str) -> CxxResult<Box<Tree
     r.error_if_base()?;
     Ok(Box::new(r))
 }
+
+pub(crate) fn treefile_delete_client_etc() -> CxxResult<()> {
+    // To be nice we don't delete the directory itself; just matching files.
+    for entry in glob(CLIENT_TREEFILES_GLOB).map_err(anyhow::Error::msg)? {
+        let cfg = entry.map_err(anyhow::Error::msg)?;
+        std::fs::remove_file(&cfg)?;
+    }
+    Ok(())
+}

src/app/rpmostree-builtin-ex.cxx

@@ -33,6 +33,10 @@ static RpmOstreeCommand ex_subcommands[] = {
     "Inspect rpm-ostree history of the system", rpmostree_ex_builtin_history },
   { "initramfs-etc", (RpmOstreeBuiltinFlags)0,
     "Track initramfs configuration files", rpmostree_ex_builtin_initramfs_etc },
+  /* This is currently only for CoreOS layering; so hide it to not confuse
+   * users. */
+  { "rebuild", (RpmOstreeBuiltinFlags)(RPM_OSTREE_BUILTIN_FLAG_HIDDEN),
+    "Rebuild system based on configuration", rpmostree_ex_builtin_rebuild },
   /* To graduate out of experimental, simply revert:
    * https://github.com/coreos/rpm-ostree/pull/3078 */
   { "module", static_cast<RpmOstreeBuiltinFlags>(0),

src/app/rpmostree-builtin-rebuild.cxx

@@ -0,0 +1,83 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2022 Red Hat, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2 of the licence or (at
+ * your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include <string.h>
+#include <glib-unix.h>
+
+#include "rpmostree-ex-builtins.h"
+#include "rpmostree-libbuiltin.h"
+#include "rpmostree-clientlib.h"
+#include "rpmostree-container.h"
+
+#include <libglnx.h>
+
+gboolean
+rpmostree_ex_builtin_rebuild (int             argc,
+                              char          **argv,
+                              RpmOstreeCommandInvocation *invocation,
+                              GCancellable   *cancellable,
+                              GError        **error)
+{
+  g_autoptr(GOptionContext) context = g_option_context_new ("");
+
+  if (!rpmostree_option_context_parse (context,
+                                       NULL,
+                                       &argc, &argv,
+                                       invocation,
+                                       cancellable,
+                                       NULL, NULL, NULL,
+                                       error))
+    return FALSE;
+
+  bool in_container = false;
+  if (rpmostreecxx::running_in_container())
+    {
+      auto is_ostree_container = CXX_TRY_VAL(is_ostree_container(), error);
+      if (!is_ostree_container)
+        return glnx_throw (error, "This command can only run in an OSTree container.");
+      in_container = true;
+    }
+
+  auto basearch = rpmostreecxx::get_rpm_basearch();
+  auto treefile = CXX_TRY_VAL(treefile_new_client_from_etc (basearch), error);
+
+  /* This is the big switch: we support running this command in two modes:
+   * "client containers", where the effect takes place in the active rootfs, and
+   * possibly eventually "client host systems", where the effect takes place in
+   * a new deployment. */
+  if (in_container)
+    {
+      if (!rpmostree_container_rebuild (*treefile, cancellable, error))
+        return FALSE;
+
+      /* In the container flow, we effectively "consume" the treefiles after
+       * modifying the rootfs. */
+      CXX_TRY(treefile_delete_client_etc (), error);
+    }
+  else
+    {
+      return glnx_throw (error, "This command is not yet supported on host systems. "
+                                "See https://github.com/coreos/rpm-ostree/issues/2326.");
+    }
+
+  return TRUE;
+}

src/app/rpmostree-ex-builtins.h

@@ -35,6 +35,7 @@ BUILTINPROTO(apply_live);
 BUILTINPROTO(history);
 BUILTINPROTO(initramfs_etc);
 BUILTINPROTO(module);
+BUILTINPROTO(rebuild);
 
 #undef BUILTINPROTO
 

src/libpriv/rpmostree-container.cxx

@@ -0,0 +1,62 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2022 Red Hat, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2 of the licence or (at
+ * your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include <string.h>
+#include <glib-unix.h>
+
+#include "rpmostree-core.h"
+#include "rpmostree-container.h"
+
+#include <libglnx.h>
+
+gboolean
+rpmostree_container_rebuild (rpmostreecxx::Treefile &treefile,
+                             GCancellable           *cancellable,
+                             GError                **error)
+{
+  auto packages = treefile.get_packages();
+
+  /* for now, we only support package installs */
+  if (packages.empty())
+    return TRUE;
+
+  g_autoptr(RpmOstreeContext) ctx = rpmostree_context_new_container ();
+  rpmostree_context_set_treefile (ctx, treefile);
+
+  if (!rpmostree_context_setup (ctx, "/", "/", cancellable, error))
+    return FALSE;
+
+  if (!rpmostree_context_prepare (ctx, cancellable, error))
+    return FALSE;
+
+  if (!rpmostree_context_download (ctx, cancellable, error))
+    return FALSE;
+
+  DnfContext *dnfctx = rpmostree_context_get_dnf (ctx);
+
+  /* can't use cancellable here because it wants to re-set it on the state,
+   * which will trigger an assertion; XXX: tweak libdnf */
+  if (!dnf_context_run (dnfctx, NULL, error))
+    return FALSE;
+
+  return TRUE;
+}

src/libpriv/rpmostree-container.h

@@ -0,0 +1,30 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2022 Red Hat, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2 of the licence or (at
+ * your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#pragma once
+
+G_BEGIN_DECLS
+
+gboolean
+rpmostree_container_rebuild (rpmostreecxx::Treefile &treefile,
+                             GCancellable           *cancellable,
+                             GError                **error);
+
+G_END_DECLS