controller: set deployedDigest and updateAvailable in driveRollout

Now we start actually updating some of the domain-specific pool status
bits.

In this one, we update deployedDigest once a rollout is complete. And
similarly we keep updateAvailable updated based on whether we've
converged to the targetDigest or not.

Assisted-by: Pi (Claude Opus 4.6)

Author: jlebon

internal/controller/rollout.go

@@ -66,13 +66,15 @@ func (r *BootcNodePoolReconciler) driveRollout(ctx context.Context, pool *bootcv
 		return fmt.Errorf("freeing completed slots: %w", err)
 	}
 
-	maxUnavail, err := resolveMaxUnavailable(pool, rs.nodeCount())
-	if err != nil {
-		return err
+	// Update deployedDigest: if every node is running the target image,
+	// the rollout is converged. Otherwise, clear it — nodes aren't all
+	// on the same digest (e.g. mid-rollout or a new node joined).
+	if len(rs.upToDate) == rs.nodeCount() {
+		pool.Status.DeployedDigest = pool.Status.TargetDigest
+	} else {
+		pool.Status.DeployedDigest = ""
 	}
-
-	avail := max(0, maxUnavail-rs.occupiedSlots)
-	candidates := selectDrainCandidates(rs.staged, avail)
+	pool.Status.UpdateAvailable = pool.Status.TargetDigest != pool.Status.DeployedDigest
 
 	log.V(1).Info("Rollout state",
 		"upToDate", len(rs.upToDate),
@@ -83,6 +85,22 @@ func (r *BootcNodePoolReconciler) driveRollout(ctx context.Context, pool *bootcv
 		"degraded", len(rs.degraded),
 		"unclassified", nodeNames(rs.unclassified),
 		"occupiedSlots", rs.occupiedSlots,
+		"updateAvailable", pool.Status.UpdateAvailable,
+	)
+
+	if !pool.Status.UpdateAvailable {
+		return nil
+	}
+
+	maxUnavail, err := resolveMaxUnavailable(pool, rs.nodeCount())
+	if err != nil {
+		return err
+	}
+
+	avail := max(0, maxUnavail-rs.occupiedSlots)
+	candidates := selectDrainCandidates(rs.staged, avail)
+
+	log.V(1).Info("Rollout candidates",
 		"maxUnavailable", maxUnavail,
 		"availableSlots", avail,
 		"candidates", nodeNames(candidates),

internal/controller/rollout_envtest_test.go

@@ -71,6 +71,16 @@ func TestSimpleRollout(t *testing.T) {
 		simulateDaemonStatus(g, ctx, name, testDigestA, bootcv1alpha1.NodeReasonStaged)
 	}
 
+	// During rollout: deployedDigest is empty (never converged) and
+	// updateAvailable is true.
+	g.Eventually(func(g Gomega) {
+		g.Expect(k8sClient.Get(ctx, client.ObjectKey{Name: poolName}, pool)).To(Succeed())
+		g.Expect(pool.Status.DeployedDigest).To(BeEmpty(),
+			"deployedDigest should be empty during rollout")
+		g.Expect(pool.Status.UpdateAvailable).To(BeTrue(),
+			"updateAvailable should be true during rollout")
+	}).Should(Succeed())
+
 	// Verify the sequential rollout: with maxUnavailable: 1 and
 	// alphabetical candidate selection, nodes are processed in
 	// deterministic order w1 → w2 → w3.
@@ -128,6 +138,16 @@ func TestSimpleRollout(t *testing.T) {
 				"node %s should be uncordoned after reboot", name)
 		}).Should(Succeed())
 	}
+
+	// After rollout: all nodes converged, deployedDigest matches target,
+	// updateAvailable is false.
+	g.Eventually(func(g Gomega) {
+		g.Expect(k8sClient.Get(ctx, client.ObjectKey{Name: poolName}, pool)).To(Succeed())
+		g.Expect(pool.Status.DeployedDigest).To(Equal(testDigestB),
+			"deployedDigest should match targetDigest after rollout")
+		g.Expect(pool.Status.UpdateAvailable).To(BeFalse(),
+			"updateAvailable should be false after rollout")
+	}).Should(Succeed())
 }
 
 // simulateDaemonStatus writes BootcNode status as if the daemon had