fix(cmr) expose all controller addresses cross-controller

We were previously sourcing addresses for cross-controller info from
APIHostPortsForAgents and prioritising for local-cloud scope.

This meant that we were not exposing public addresses resulting in some
CMRs not being able to contact remote controllers.

Here we user APIHostPortsForClients, which includes public addresses,
and we prioritise for the public scope.

apiserver/facades/controller/crosscontroller/register.go

@@ -8,8 +8,9 @@ import (
 
 	"github.com/juju/errors"
 
-	"github.com/juju/juju/apiserver/common"
 	"github.com/juju/juju/apiserver/facade"
+	"github.com/juju/juju/core/network"
+	"github.com/juju/juju/state"
 )
 
 // Register is called to expose a package of facades onto a given registry.
@@ -26,7 +27,7 @@ func newStateCrossControllerAPI(ctx facade.Context) (*CrossControllerAPI, error)
 	return NewCrossControllerAPI(
 		ctx.Resources(),
 		func() ([]string, string, error) {
-			return common.StateControllerInfo(st)
+			return controllerInfo(st)
 		},
 		func() (string, error) {
 			config, err := st.ControllerConfig()
@@ -38,3 +39,28 @@ func newStateCrossControllerAPI(ctx facade.Context) (*CrossControllerAPI, error)
 		st.WatchAPIHostPortsForClients,
 	)
 }
+
+func controllerInfo(st *state.State) ([]string, string, error) {
+	apiHostPorts, err := st.APIHostPortsForClients()
+	if err != nil {
+		return nil, "", errors.Trace(err)
+	}
+
+	var addrs []string
+	for _, hostPorts := range apiHostPorts {
+		ordered := hostPorts.HostPorts().PrioritizedForScope(network.ScopeMatchPublic)
+		for _, addr := range ordered {
+			if addr != "" {
+				addrs = append(addrs, addr)
+			}
+		}
+	}
+
+	controllerConfig, err := st.ControllerConfig()
+	if err != nil {
+		return nil, "", errors.Trace(err)
+	}
+
+	caCert, _ := controllerConfig.CACert()
+	return addrs, caCert, nil
+}