Planner bg task: Save report even if we don't make a new target (#9088)

We talked about putting the background task's report in a watch channel,
and we might still want to do that if we decide we want to expose it in
the external API. But this change puts it into the _existing_ watch
channel that omdb can poke for debugging, and is a really trivial
change. With this it should be easy to compare the report of the current
target blueprint with the report of running the planner again after it's
realized.

Author: jgallagher

dev-tools/omdb/src/bin/omdb/nexus.rs

@@ -1295,14 +1295,20 @@ fn print_task_blueprint_planner(details: &serde_json::Value) {
         BlueprintPlannerStatus::Error(error) => {
             println!("    task did not complete successfully: {error}");
         }
-        BlueprintPlannerStatus::Unchanged { parent_blueprint_id } => {
+        BlueprintPlannerStatus::Unchanged { parent_blueprint_id, report } => {
             println!("    plan unchanged from parent {parent_blueprint_id}");
+            println!("{report}");
         }
-        BlueprintPlannerStatus::Planned { parent_blueprint_id, error } => {
+        BlueprintPlannerStatus::Planned {
+            parent_blueprint_id,
+            error,
+            report,
+        } => {
             println!(
                 "    planned new blueprint from parent {parent_blueprint_id}, \
                      but could not make it the target: {error}"
             );
+            println!("{report}");
         }
         BlueprintPlannerStatus::Targeted { blueprint_id, report, .. } => {
             println!(

nexus/src/app/background/tasks/blueprint_planner.rs

@@ -176,6 +176,25 @@ impl BlueprintPlanner {
             }
         };
 
+        // We just ran the planner, so we should always get its report. This
+        // output is for debugging only, though, so just make an empty one in
+        // the unreachable arms.
+        let report = match &blueprint.source {
+            BlueprintSource::Planner(report) => Arc::clone(report),
+            BlueprintSource::Rss
+            | BlueprintSource::PlannerLoadedFromDatabase
+            | BlueprintSource::ReconfiguratorCliEdit
+            | BlueprintSource::Test => {
+                warn!(
+                    &opctx.log,
+                    "ran planner, but got unexpected blueprint source; \
+                     generating an empty planning report";
+                    "source" => ?&blueprint.source,
+                );
+                Arc::new(PlanningReport::new())
+            }
+        };
+
         // Compare the new blueprint to its parent.
         {
             let summary = blueprint.diff_since_blueprint(&parent);
@@ -188,6 +207,7 @@ impl BlueprintPlanner {
                 );
                 return BlueprintPlannerStatus::Unchanged {
                     parent_blueprint_id,
+                    report,
                 };
             }
         }
@@ -255,30 +275,13 @@ impl BlueprintPlanner {
                 return BlueprintPlannerStatus::Planned {
                     parent_blueprint_id,
                     error: format!("{error}"),
+                    report,
                 };
             }
         }
 
         // We have a new target!
 
-        // We just ran the planner, so we should always get its report. This
-        // output is for debugging only, though, so just make an empty one in
-        // the unreachable arms.
-        let report = match &blueprint.source {
-            BlueprintSource::Planner(report) => Arc::clone(report),
-            BlueprintSource::Rss
-            | BlueprintSource::PlannerLoadedFromDatabase
-            | BlueprintSource::ReconfiguratorCliEdit
-            | BlueprintSource::Test => {
-                warn!(
-                    &opctx.log,
-                    "ran planner, but got unexpected blueprint source; \
-                     generating an empty planning report";
-                    "source" => ?&blueprint.source,
-                );
-                Arc::new(PlanningReport::new())
-            }
-        };
         self.tx_blueprint.send_replace(Some(Arc::new((target, blueprint))));
         BlueprintPlannerStatus::Targeted {
             parent_blueprint_id,
@@ -313,6 +316,7 @@ mod test {
     use crate::app::background::tasks::blueprint_load::TargetBlueprintLoader;
     use crate::app::background::tasks::inventory_collection::InventoryCollector;
     use crate::app::{background::Activator, quiesce::NexusQuiesceHandle};
+    use assert_matches::assert_matches;
     use nexus_inventory::now_db_precision;
     use nexus_test_utils_macros::nexus_test;
     use nexus_types::deployment::{
@@ -420,11 +424,12 @@ mod test {
             planner.activate(&opctx).await,
         )
         .expect("can't re-activate planner");
-        assert_eq!(
+        assert_matches!(
             status,
             BlueprintPlannerStatus::Unchanged {
-                parent_blueprint_id: blueprint_id,
-            }
+                parent_blueprint_id,
+                report: _,
+            } if parent_blueprint_id == parent_blueprint_id
         );
 
         // Enable execution.
@@ -488,11 +493,12 @@ mod test {
             planner.activate(&opctx).await,
         )
         .expect("can't re-activate planner");
-        assert_eq!(
+        assert_matches!(
             status,
             BlueprintPlannerStatus::Unchanged {
-                parent_blueprint_id: blueprint_id,
-            }
+                parent_blueprint_id,
+                report: _,
+            } if parent_blueprint_id == blueprint_id
         );
     }
 }

nexus/types/src/internal_api/background.rs

@@ -492,11 +492,18 @@ pub enum BlueprintPlannerStatus {
 
     /// Planning produced a blueprint identital to the current target,
     /// so we threw it away and did nothing.
-    Unchanged { parent_blueprint_id: BlueprintUuid },
+    Unchanged {
+        parent_blueprint_id: BlueprintUuid,
+        report: Arc<PlanningReport>,
+    },
 
     /// Planning produced a new blueprint, but we failed to make it
     /// the current target and so deleted it.
-    Planned { parent_blueprint_id: BlueprintUuid, error: String },
+    Planned {
+        parent_blueprint_id: BlueprintUuid,
+        error: String,
+        report: Arc<PlanningReport>,
+    },
 
     /// Planing succeeded, and we saved and made the new blueprint the
     /// current target.