Add an 3.4.3 upgrade step.

Using the AssignArchToContainers method to fix the instance data of
containers. The method was merged forward from 3.3.5. However we need a
different upgrade step in 3.4

upgrades/operations.go

@@ -20,6 +20,7 @@ import (
 var stateUpgradeOperations = func() []Operation {
 	steps := []Operation{
 		upgradeToVersion{version.MustParse("3.4.1"), stateStepsFor341()},
+		upgradeToVersion{version.MustParse("3.4.3"), stateStepsFor343()},
 	}
 	return steps
 }

upgrades/steps_343.go

@@ -0,0 +1,16 @@
+// Copyright 2024 Canonical Ltd.
+// Licensed under the AGPLv3, see LICENCE file for details.
+
+package upgrades
+
+func stateStepsFor343() []Step {
+	return []Step{
+		&upgradeStep{
+			description: "assign architectures to container's instance data",
+			targets:     []Target{DatabaseMaster},
+			run: func(context Context) error {
+				return context.State().AssignArchToContainers()
+			},
+		},
+	}
+}

upgrades/steps_343_test.go

@@ -0,0 +1,26 @@
+// Copyright 2024 Canonical Ltd.
+// Licensed under the AGPLv3, see LICENCE file for details.
+
+package upgrades_test
+
+import (
+	jc "github.com/juju/testing/checkers"
+	"github.com/juju/version/v2"
+	gc "gopkg.in/check.v1"
+
+	"github.com/juju/juju/testing"
+	"github.com/juju/juju/upgrades"
+)
+
+var v343 = version.MustParse("3.4.3")
+
+type steps342Suite struct {
+	testing.BaseSuite
+}
+
+var _ = gc.Suite(&steps342Suite{})
+
+func (s *steps342Suite) TestAssignArchToContainers(c *gc.C) {
+	step := findStateStep(c, v343, "assign architectures to container's instance data")
+	c.Assert(step.Targets(), jc.DeepEquals, []upgrades.Target{upgrades.DatabaseMaster})
+}

upgrades/upgrade_test.go

@@ -598,6 +598,7 @@ func (s *upgradeSuite) TestStateUpgradeOperationsVersions(c *gc.C) {
 	versions := extractUpgradeVersions(c, (*upgrades.StateUpgradeOperations)())
 	c.Assert(versions, gc.DeepEquals, []string{
 		"3.4.1",
+		"3.4.3",
 	})
 }