[nexus] Improve logging for schema changes (#4309)

Improves visibility of logging, indicating:
- What version are we upgrading into, throughout the process
- Logging the names of SQL files used for upgrade, as they occur

nexus/db-queries/src/db/datastore/db_metadata.rs

@@ -25,6 +25,17 @@ use std::str::FromStr;
 
 pub const EARLIEST_SUPPORTED_VERSION: &'static str = "1.0.0";
 
+/// Describes a single file containing a schema change, as SQL.
+pub struct SchemaUpgradeStep {
+    pub path: Utf8PathBuf,
+    pub sql: String,
+}
+
+/// Describes a sequence of files containing schema changes.
+pub struct SchemaUpgrade {
+    pub steps: Vec<SchemaUpgradeStep>,
+}
+
 /// Reads a "version directory" and reads all SQL changes into
 /// a result Vec.
 ///
@@ -34,7 +45,7 @@ pub const EARLIEST_SUPPORTED_VERSION: &'static str = "1.0.0";
 /// These are sorted lexicographically.
 pub async fn all_sql_for_version_migration<P: AsRef<Utf8Path>>(
     path: P,
-) -> Result<Vec<String>, String> {
+) -> Result<SchemaUpgrade, String> {
     let target_dir = path.as_ref();
     let mut up_sqls = vec![];
     let entries = target_dir
@@ -54,13 +65,12 @@ pub async fn all_sql_for_version_migration<P: AsRef<Utf8Path>>(
     }
     up_sqls.sort();
 
-    let mut result = vec![];
+    let mut result = SchemaUpgrade { steps: vec![] };
     for path in up_sqls.into_iter() {
-        result.push(
-            tokio::fs::read_to_string(&path)
-                .await
-                .map_err(|e| format!("Cannot read {path}: {e}"))?,
-        );
+        let sql = tokio::fs::read_to_string(&path)
+            .await
+            .map_err(|e| format!("Cannot read {path}: {e}"))?;
+        result.steps.push(SchemaUpgradeStep { path: path.to_owned(), sql });
     }
     Ok(result)
 }
@@ -187,7 +197,8 @@ impl DataStore {
             )
             .map_err(|e| format!("Invalid schema path: {}", e.display()))?;
 
-            let up_sqls = all_sql_for_version_migration(&target_dir).await?;
+            let schema_change =
+                all_sql_for_version_migration(&target_dir).await?;
 
             // Confirm the current version, set the "target_version"
             // column to indicate that a schema update is in-progress.
@@ -205,7 +216,7 @@ impl DataStore {
                 "target_version" => target_version.to_string(),
             );
 
-            for sql in &up_sqls {
+            for SchemaUpgradeStep { path: _, sql } in &schema_change.steps {
                 // Perform the schema change.
                 self.apply_schema_update(
                     &current_version,

nexus/db-queries/src/db/datastore/mod.rs

@@ -91,7 +91,8 @@ mod zpool;
 
 pub use address_lot::AddressLotCreateResult;
 pub use db_metadata::{
-    all_sql_for_version_migration, EARLIEST_SUPPORTED_VERSION,
+    all_sql_for_version_migration, SchemaUpgrade, SchemaUpgradeStep,
+    EARLIEST_SUPPORTED_VERSION,
 };
 pub use dns::DnsVersionUpdateBuilder;
 pub use instance::InstanceAndActiveVmm;

nexus/tests/integration_tests/schema.rs

@@ -89,6 +89,7 @@ async fn apply_update_as_transaction(
         match apply_update_as_transaction_inner(client, sql).await {
             Ok(()) => break,
             Err(err) => {
+                warn!(log, "Failed to apply update as transaction"; "err" => err.to_string());
                 client
                     .batch_execute("ROLLBACK;")
                     .await
@@ -111,7 +112,9 @@ async fn apply_update(
     version: &str,
     times_to_apply: usize,
 ) {
-    info!(log, "Performing upgrade to {version}");
+    let log = log.new(o!("target version" => version.to_string()));
+    info!(log, "Performing upgrade");
+
     let client = crdb.connect().await.expect("failed to connect");
 
     // We skip this for the earliest supported version because these tables
@@ -126,11 +129,15 @@ async fn apply_update(
     }
 
     let target_dir = Utf8PathBuf::from(SCHEMA_DIR).join(version);
-    let sqls = all_sql_for_version_migration(&target_dir).await.unwrap();
+    let schema_change =
+        all_sql_for_version_migration(&target_dir).await.unwrap();
 
     for _ in 0..times_to_apply {
-        for sql in sqls.iter() {
-            apply_update_as_transaction(log, &client, sql).await;
+        for nexus_db_queries::db::datastore::SchemaUpgradeStep { path, sql } in
+            &schema_change.steps
+        {
+            info!(log, "Applying sql schema upgrade step"; "path" => path.to_string());
+            apply_update_as_transaction(&log, &client, sql).await;
         }
     }