compose: Add rpmdb option, default to bdb

The design of https://fedoraproject.org/wiki/Changes/Sqlite_Rpmdb
is problematic for us for multiple reasons.  The first big reason
is that rpm-ostree is designed for "cross" builds and e.g. today
we use a Fedora-derived container to build RHEL CoreOS images.

However the default database lives inside the `rpm` package which
means that if we e.g. upgrade the coreos-assembler container to F33
it will suddenly try to use sqlite for RHCOS which is obviously broken.

Related to this, rebases from f32 to f33 w/layered packages
are broken: https://bugzilla.redhat.com/show_bug.cgi?id=1876194#c3

With this we can configure things to continue to use bdb for f33
for ostree-based systems, so that by enforcing an upgrade order
f32 → f33 [bdb] → f34 [sqlite] ... the intermediate f33 w/bdb
still understands sqlite and hence rebases will work.

docs/manual/treefile.md

@@ -94,6 +94,10 @@ It supports the following parameters:
     specific filesystem drivers are included.  If not specified,
     `--no-hostonly` will be used.
 
+ * `rpmdb`: String, optional: The RPM database backend.  Can be one of
+    `bdb`, `ndb`, or `sqlite`.  If unspecified, defaults to `bdb` for
+    compatibility.
+
  * `cliwrap`: boolean, optional.  Defaults to `false`.  If enabled,
     rpm-ostree will replace binaries such as `/usr/bin/rpm` with
     wrappers that intercept unsafe operations, or adjust functionality.

rust/src/treefile.rs

@@ -306,6 +306,7 @@ fn treefile_merge(dest: &mut TreeComposeConfig, src: &mut TreeComposeConfig) {
         releasever,
         automatic_version_prefix,
         automatic_version_suffix,
+        rpmdb,
         mutate_os_release,
         preserve_passwd,
         check_passwd,
@@ -681,6 +682,16 @@ enum Include {
     Multiple(Vec<String>),
 }
 
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq)]
+#[serde(rename_all = "kebab-case")]
+/// The database backend; see https://github.com/coreos/fedora-coreos-tracker/issues/609
+/// and https://fedoraproject.org/wiki/Changes/Sqlite_Rpmdb
+enum RpmdbBackend {
+    BDB,
+    Sqlite,
+    NDB,
+}
+
 // Because of how we handle includes, *everything* here has to be
 // Option<T>.  The defaults live in the code (e.g. machineid-compat defaults
 // to `true`).
@@ -821,6 +832,10 @@ struct TreeComposeConfig {
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(rename = "add-commit-metadata")]
     add_commit_metadata: Option<BTreeMap<String, serde_json::Value>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[serde(rename = "rpmdb")]
+    // The database backend
+    rpmdb: Option<RpmdbBackend>,
 
     #[serde(flatten)]
     legacy_fields: LegacyTreeComposeConfigFields,
@@ -1026,6 +1041,7 @@ mutate-os-release: ${releasever}
         assert!(treefile.releasever.unwrap() == "30");
         assert!(treefile.automatic_version_prefix.unwrap() == "30");
         assert!(treefile.mutate_os_release.unwrap() == "30");
+        assert!(treefile.rpmdb.is_none());
     }
 
     #[test]
@@ -1043,12 +1059,14 @@ gpg_key: foo
 boot_location: new
 default_target: bar
 automatic_version_prefix: baz
+rpmdb: sqlite
         ",
         );
         assert!(treefile.gpg_key.unwrap() == "foo");
         assert!(treefile.boot_location.unwrap() == BootLocation::New);
         assert!(treefile.default_target.unwrap() == "bar");
         assert!(treefile.automatic_version_prefix.unwrap() == "baz");
+        assert!(treefile.rpmdb.unwrap() == RpmdbBackend::Sqlite);
     }
 
     #[test]
@@ -1512,6 +1530,17 @@ mod ffi {
         tf.parsed.readonly_executables.unwrap_or(false)
     }
 
+    #[no_mangle]
+    pub extern "C" fn ror_treefile_get_rpmdb(tf: *mut Treefile) -> *mut libc::c_char {
+        let tf = ref_from_raw_ptr(tf);
+        let s: &str = match tf.parsed.rpmdb.as_ref().unwrap_or(&RpmdbBackend::BDB) {
+            RpmdbBackend::BDB => "bdb",
+            RpmdbBackend::Sqlite => "sqlite",
+            RpmdbBackend::NDB => "ndb",
+        };
+        s.to_string().to_glib_full()
+    }
+
     #[no_mangle]
     pub extern "C" fn ror_treefile_free(tf: *mut Treefile) {
         if tf.is_null() {

src/libpriv/rpmostree-core.c

@@ -753,6 +753,15 @@ rpmostree_context_setup (RpmOstreeContext    *self,
   /* This is what we use as default. */
   dnf_context_set_rpm_macro (self->dnfctx, "_dbpath", "/" RPMOSTREE_RPMDB_LOCATION);
 
+  /* Set the database backend only in the compose path.  It then becomes the default
+   * for any client side layering.
+   */
+  if (self->treefile_rs)
+    {
+      g_autofree char *rpmdb_backend = ror_treefile_get_rpmdb (self->treefile_rs);
+      dnf_context_set_rpm_macro (self->dnfctx, "_db_backend", rpmdb_backend);
+    }
+
   if (!dnf_context_setup (self->dnfctx, cancellable, error))
     return FALSE;
 

tests/compose/libbasic-test.sh

@@ -95,6 +95,11 @@ ostree --repo=${repo} ls -R ${treeref} /usr/etc/selinux > ls.txt
 assert_not_file_has_content ls.txt 'LOCK'
 echo "ok no leftover files"
 
+ostree --repo=${repo} ls ${treeref} /usr/share/rpm > ls.txt
+assert_file_has_content ls.txt /usr/share/rpm/Packages
+assert_not_file_has_content ls.txt rpmdb.sqlite
+echo "ok rpmdb is bdb"
+
 ostree --repo=${repo} show ${treeref} \
   --print-metadata-key rpmostree.rpmdb.pkglist > pkglist.txt
 assert_file_has_content pkglist.txt 'systemd'