command: when setting up state, only write back if local is newer

command/remote_pull_test.go

@@ -80,15 +80,6 @@ func testRemoteState(t *testing.T, s *terraform.State, c int) (*terraform.Remote
 	var b64md5 string
 	buf := bytes.NewBuffer(nil)
 
-	if s != nil {
-		enc := json.NewEncoder(buf)
-		if err := enc.Encode(s); err != nil {
-			t.Fatalf("err: %v", err)
-		}
-		md5 := md5.Sum(buf.Bytes())
-		b64md5 = base64.StdEncoding.EncodeToString(md5[:16])
-	}
-
 	cb := func(resp http.ResponseWriter, req *http.Request) {
 		if req.Method == "PUT" {
 			resp.WriteHeader(c)
@@ -98,13 +89,28 @@ func testRemoteState(t *testing.T, s *terraform.State, c int) (*terraform.Remote
 			resp.WriteHeader(404)
 			return
 		}
+
 		resp.Header().Set("Content-MD5", b64md5)
 		resp.Write(buf.Bytes())
 	}
+
 	srv := httptest.NewServer(http.HandlerFunc(cb))
 	remote := &terraform.RemoteState{
 		Type:   "http",
 		Config: map[string]string{"address": srv.URL},
 	}
+
+	if s != nil {
+		// Set the remote data
+		s.Remote = remote
+
+		enc := json.NewEncoder(buf)
+		if err := enc.Encode(s); err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		md5 := md5.Sum(buf.Bytes())
+		b64md5 = base64.StdEncoding.EncodeToString(md5[:16])
+	}
+
 	return remote, srv
 }

command/state.go

@@ -231,10 +231,20 @@ func remoteState(
 				"Error reloading remote state: {{err}}", err)
 		}
 		switch cache.RefreshResult() {
+		// All the results below can be safely ignored since it means the
+		// pull was successful in some way. Noop = nothing happened.
+		// Init = both are empty. UpdateLocal = local state was older and
+		// updated.
+		//
+		// We don't have to do anything, the pull was successful.
 		case state.CacheRefreshNoop:
 		case state.CacheRefreshInit:
-		case state.CacheRefreshLocalNewer:
 		case state.CacheRefreshUpdateLocal:
+
+		// Our local state has a higher serial number than remote, so we
+		// want to explicitly sync the remote side with our local so that
+		// the remote gets the latest serial number.
+		case state.CacheRefreshLocalNewer:
 			// Write our local state out to the durable storage to start.
 			if err := cache.WriteState(local); err != nil {
 				return nil, errwrap.Wrapf(

terraform/state.go

@@ -344,6 +344,10 @@ func (r *RemoteState) Equals(other *RemoteState) bool {
 	return true
 }
 
+func (r *RemoteState) GoString() string {
+	return fmt.Sprintf("*%#v", *r)
+}
+
 // ModuleState is used to track all the state relevant to a single
 // module. Previous to Terraform 0.3, all state belonged to the "root"
 // module.