Exports Oracle cloud models with region set from credentials if it

exists there.

Old versions used region from the credential, but subsequent versions
correctly use the model's cloud region.

state/migration_export.go

@@ -129,10 +129,15 @@ func (st *State) exportImpl(cfg ExportConfig) (description.Model, error) {
 		return nil, errors.Trace(err)
 	}
 
+	region, err := deriveCloudRegion(dbModel)
+	if err != nil {
+		return nil, errors.Annotate(err, "deriving cloud region")
+	}
+
 	args := description.ModelArgs{
 		Type:               string(dbModel.Type()),
 		Cloud:              dbModel.CloudName(),
-		CloudRegion:        dbModel.CloudRegion(),
+		CloudRegion:        region,
 		Owner:              dbModel.Owner(),
 		Config:             modelConfig.Settings,
 		PasswordHash:       dbModel.doc.PasswordHash,
@@ -246,6 +251,30 @@ func (st *State) exportImpl(cfg ExportConfig) (description.Model, error) {
 	return export.model, nil
 }
 
+// deriveCloudRegion accommodates migration of the model's cloud region
+// for legacy Oracle models that derived region from credentials.
+// If this model is on OCI and its credential has a region attribute,
+// we'll use that. Otherwise, it's the model's region as usual.
+func deriveCloudRegion(m *Model) (string, error) {
+	cloud, err := m.Cloud()
+	if err != nil {
+		return "", errors.Trace(err)
+	}
+
+	if cloud.Type == "oci" {
+		cred, _, err := m.CloudCredential()
+		if err != nil {
+			return "", errors.Trace(err)
+		}
+
+		if region := cred.Attributes["region"]; region != "" {
+			return region, nil
+		}
+	}
+
+	return m.CloudRegion(), nil
+}
+
 // ExportStateMigration defines a migration for exporting various entities into
 // a destination description model from the source state.
 // It accumulates a series of migrations to run at a later time.

state/migration_export_test.go

@@ -6,6 +6,7 @@ package state_test
 import (
 	"bytes"
 	"fmt"
+	"github.com/juju/juju/cloud"
 	"io/ioutil"
 	"math/rand"
 	"time"
@@ -220,6 +221,29 @@ func (s *MigrationExportSuite) TestModelInfo(c *gc.C) {
 	})
 }
 
+func (s *MigrationExportSuite) TestModelRegionForOCICLoud(c *gc.C) {
+	cl, err := s.Model.Cloud()
+	c.Assert(err, jc.ErrorIsNil)
+
+	cl.Type = "oci"
+	err = s.State.UpdateCloud(cl)
+	c.Assert(err, jc.ErrorIsNil)
+
+	tag := names.NewCloudCredentialTag(fmt.Sprintf("%s/owner/name", cl.Name))
+	err = s.State.UpdateCloudCredential(tag, cloud.NewCredential(cloud.EmptyAuthType, map[string]string{
+		"region": "nether",
+	}))
+	c.Assert(err, jc.ErrorIsNil)
+
+	_, err = s.Model.SetCloudCredential(tag)
+	c.Assert(err, jc.ErrorIsNil)
+
+	model, err := s.State.Export()
+	c.Assert(err, jc.ErrorIsNil)
+
+	c.Check(model.CloudRegion(), gc.Equals, "nether")
+}
+
 func (s *MigrationExportSuite) TestModelUsers(c *gc.C) {
 	// Make sure we have some last connection times for the admin user,
 	// and create a few other users.