(1/N) db_metadata_nexus schema changes, db queries. Populate the tables (#8924)

Split off of #8845

Creates the schema, ensures it stays up-to-date. Does not attempt to
read it.

First part of #8501: adding schema for records, writing them. Not yet
reading these records.

Author: smklein

nexus/db-model/src/db_metadata.rs

@@ -3,8 +3,14 @@
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 use crate::SemverVersion;
+use crate::impl_enum_type;
+use crate::typed_uuid::DbTypedUuid;
 use chrono::{DateTime, Utc};
 use nexus_db_schema::schema::db_metadata;
+use nexus_db_schema::schema::db_metadata_nexus;
+use omicron_uuid_kinds::{
+    BlueprintKind, BlueprintUuid, OmicronZoneKind, OmicronZoneUuid,
+};
 use serde::{Deserialize, Serialize};
 
 /// Internal database metadata
@@ -33,3 +39,47 @@ impl DbMetadata {
         &self.version
     }
 }
+
+impl_enum_type!(
+    DbMetadataNexusStateEnum:
+
+    #[derive(Clone, Copy, Debug, AsExpression, FromSqlRow, PartialEq, Serialize, Deserialize)]
+    pub enum DbMetadataNexusState;
+
+    // Enum values
+    Active => b"active"
+    NotYet => b"not_yet"
+    Quiesced => b"quiesced"
+);
+
+#[derive(
+    Queryable, Insertable, Debug, Clone, Selectable, Serialize, Deserialize,
+)]
+#[diesel(table_name = db_metadata_nexus)]
+pub struct DbMetadataNexus {
+    nexus_id: DbTypedUuid<OmicronZoneKind>,
+    last_drained_blueprint_id: Option<DbTypedUuid<BlueprintKind>>,
+    state: DbMetadataNexusState,
+}
+
+impl DbMetadataNexus {
+    pub fn new(nexus_id: OmicronZoneUuid, state: DbMetadataNexusState) -> Self {
+        Self {
+            nexus_id: nexus_id.into(),
+            last_drained_blueprint_id: None,
+            state,
+        }
+    }
+
+    pub fn state(&self) -> DbMetadataNexusState {
+        self.state
+    }
+
+    pub fn nexus_id(&self) -> OmicronZoneUuid {
+        self.nexus_id.into()
+    }
+
+    pub fn last_drained_blueprint_id(&self) -> Option<BlueprintUuid> {
+        self.last_drained_blueprint_id.map(|id| id.into())
+    }
+}

nexus/db-model/src/schema_versions.rs

@@ -16,7 +16,7 @@ use std::{collections::BTreeMap, sync::LazyLock};
 ///
 /// This must be updated when you change the database schema.  Refer to
 /// schema/crdb/README.adoc in the root of this repository for details.
-pub const SCHEMA_VERSION: Version = Version::new(184, 0, 0);
+pub const SCHEMA_VERSION: Version = Version::new(185, 0, 0);
 
 /// List of all past database schema versions, in *reverse* order
 ///
@@ -28,6 +28,7 @@ static KNOWN_VERSIONS: LazyLock<Vec<KnownVersion>> = LazyLock::new(|| {
         // |  leaving the first copy as an example for the next person.
         // v
         // KnownVersion::new(next_int, "unique-dirname-with-the-sql-files"),
+        KnownVersion::new(185, "populate-db-metadata-nexus"),
         KnownVersion::new(184, "store-silo-admin-group-name"),
         KnownVersion::new(183, "add-ip-version-to-pools"),
         KnownVersion::new(182, "add-tuf-artifact-board"),
@@ -228,6 +229,9 @@ static KNOWN_VERSIONS: LazyLock<Vec<KnownVersion>> = LazyLock::new(|| {
 /// The earliest supported schema version.
 pub const EARLIEST_SUPPORTED_VERSION: Version = Version::new(1, 0, 0);
 
+/// The version where "db_metadata_nexus" was added.
+pub const DB_METADATA_NEXUS_SCHEMA_VERSION: Version = Version::new(185, 0, 0);
+
 /// Describes one version of the database schema
 #[derive(Debug, Clone)]
 struct KnownVersion {