fix: Caddy config regeneration due to non-deterministic container serialisation (fixes #111)

internal/machine/dns/resolver_test.go

@@ -0,0 +1,77 @@
+package dns
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/docker/docker/api/types/container"
+	"github.com/docker/docker/api/types/network"
+	"github.com/psviderski/uncloud/internal/machine/store"
+	"github.com/psviderski/uncloud/pkg/api"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestClusterResolver_UpdateServiceIPs(t *testing.T) {
+	t.Parallel()
+
+	containers := []store.ContainerRecord{
+		newRecord("svc-id-1", "web", "10.210.0.2", "mach-1"),
+		newRecord("svc-id-1", "web", "10.210.0.3", "mach-2"),
+		newRecord("svc-id-2", "api", "10.210.1.2", "mach-1"),
+	}
+
+	r := NewClusterResolver(nil)
+	r.updateServiceIPs(containers)
+
+	firstMapPtr := reflect.ValueOf(r.serviceIPs).Pointer()
+	assert.NotZero(t, firstMapPtr, "first call should populate the map")
+	assert.NotEmpty(t, r.Resolve("web"))
+	assert.NotEmpty(t, r.Resolve("api"))
+
+	// Second call with the same input must not swap the map.
+	r.updateServiceIPs(containers)
+	assert.Equal(t, firstMapPtr, reflect.ValueOf(r.serviceIPs).Pointer(),
+		"second call with identical input must not rewrite the map")
+
+	// Reordering the input also must not rewrite the map.
+	reordered := []store.ContainerRecord{containers[2], containers[0], containers[1]}
+	r.updateServiceIPs(reordered)
+	assert.Equal(t, firstMapPtr, reflect.ValueOf(r.serviceIPs).Pointer(),
+		"reordered input with same containers must not rewrite the map")
+
+	// A real change must rewrite the map.
+	changed := append([]store.ContainerRecord{}, containers...)
+	changed = append(changed, newRecord("svc-id-3", "db", "10.210.2.2", "mach-1"))
+	r.updateServiceIPs(changed)
+	assert.NotEqual(t, firstMapPtr, reflect.ValueOf(r.serviceIPs).Pointer(),
+		"adding a new service should rewrite the map")
+	assert.NotEmpty(t, r.Resolve("db"))
+}
+
+func newRecord(serviceID, serviceName, ip, machineID string) store.ContainerRecord {
+	return store.ContainerRecord{
+		Container: api.ServiceContainer{
+			Container: api.Container{
+				InspectResponse: container.InspectResponse{
+					ContainerJSONBase: &container.ContainerJSONBase{
+						ID:    serviceName + "-" + ip,
+						State: &container.State{Running: true},
+					},
+					NetworkSettings: &container.NetworkSettings{
+						Networks: map[string]*network.EndpointSettings{
+							// Hardcoded to avoid an import cycle via internal/machine/docker.
+							"uncloud": {IPAddress: ip},
+						},
+					},
+					Config: &container.Config{
+						Labels: map[string]string{
+							api.LabelServiceID:   serviceID,
+							api.LabelServiceName: serviceName,
+						},
+					},
+				},
+			},
+		},
+		MachineID: machineID,
+	}
+}