WEBVTT 00:00.000 --> 00:02.790 -: All right my friends, we've now got our application 00:02.790 --> 00:04.260 up and running with Kubernetes 00:04.260 --> 00:06.660 but there's one last thing I want to show you. 00:06.660 --> 00:08.580 Right now, we don't really have a good setup 00:08.580 --> 00:10.080 for running our code locally 00:10.080 --> 00:12.570 and doing local development with Kubernetes. 00:12.570 --> 00:15.030 Sure, we can deploy to our mini cube cluster 00:15.030 --> 00:16.560 but going through the process of actually 00:16.560 --> 00:19.530 developing our application is a little bit awkward. 00:19.530 --> 00:21.300 Let me show you what I mean. 00:21.300 --> 00:23.820 If you recall back on the Docker Compose stuff we did, 00:23.820 --> 00:27.960 we had set up a client container for our React project. 00:27.960 --> 00:30.780 When we made use of Docker Compose, we set up a volume 00:30.780 --> 00:33.210 that mapped our local React Project directory 00:33.210 --> 00:34.380 into that volume. 00:34.380 --> 00:37.200 So essentially, we were sharing our source code 00:37.200 --> 00:40.830 between our local file system and that client container. 00:40.830 --> 00:42.600 That meant that anytime we changed our code 00:42.600 --> 00:45.330 on our local machine, it updated the code inside 00:45.330 --> 00:47.700 the container as well, and the React application 00:47.700 --> 00:50.970 automatically updated right before our eyes. 00:50.970 --> 00:54.210 Now this system only works with Docker Composed right now 00:54.210 --> 00:57.300 we don't really have anything equivalent for Kubernetes. 00:57.300 --> 00:59.520 So right now if you and I wanted to make some change 00:59.520 --> 01:02.400 to our local React Project during development, 01:02.400 --> 01:05.010 we don't have any easy way to somehow inject 01:05.010 --> 01:07.980 that source code into our client pod. 01:07.980 --> 01:10.200 Instead, we would have to completely rebuild 01:10.200 --> 01:15.180 the client image and then rerun that Cube CTL apply command. 01:15.180 --> 01:16.443 That's definitely a pain. 01:17.340 --> 01:18.690 So let me show you a better way to handle 01:18.690 --> 01:20.460 this development process. 01:20.460 --> 01:23.370 We're going to be making use of a tool called Scaffold. 01:23.370 --> 01:26.670 This is a command line tool separate from Kubernetes 01:26.670 --> 01:28.830 but designed to be used with Kubernetes 01:28.830 --> 01:31.560 just to facilitate local development. 01:31.560 --> 01:33.270 Here's how Scaffold works. 01:33.270 --> 01:36.000 Scaffold is going to watch our local React Project 01:36.000 --> 01:37.380 directory for changes. 01:37.380 --> 01:39.600 So you and I might then open up our code editor 01:39.600 --> 01:43.020 and change some React component or whatever else. 01:43.020 --> 01:45.720 Once we save that file, Scaffold is gonna see that 01:45.720 --> 01:47.760 a change occurred and then Scaffold 01:47.760 --> 01:50.100 is gonna jump into action. 01:50.100 --> 01:53.250 Scaffold is all about somehow taking that change in our code 01:53.250 --> 01:56.400 and getting it reflected inside of our Kubernetes cluster. 01:56.400 --> 01:59.040 It can do that with one of two different modes 01:59.040 --> 02:02.100 and we're going to explore both these different modes. 02:02.100 --> 02:04.170 The first way that Scaffold is going to somehow 02:04.170 --> 02:06.390 update our client pod inside of our cluster 02:06.390 --> 02:08.100 is just automatically rebuild 02:08.100 --> 02:10.440 the entire client image from scratch. 02:10.440 --> 02:13.650 When I say from scratch, I don't mean like rerun 02:13.650 --> 02:16.320 every single step including installing dependencies, 02:16.320 --> 02:19.290 it will be just a normal Docker build process. 02:19.290 --> 02:22.650 Scaffold is going to tell Docker to rebuild the client. 02:22.650 --> 02:24.690 Docker is going to see that the only change we made 02:24.690 --> 02:26.730 was to our source code, and so it's essentially 02:26.730 --> 02:28.380 just going to stick that source code 02:28.380 --> 02:30.750 into a new updated image. 02:30.750 --> 02:33.240 Scaffold will then take that image and update 02:33.240 --> 02:35.760 our local Kubernetes cluster, and then we should see 02:35.760 --> 02:37.983 our updated application appear. 02:39.000 --> 02:41.100 Now that process is still a little bit slow 02:41.100 --> 02:42.990 because we have to go through that entire sequence 02:42.990 --> 02:45.360 of rebuilding the image, even though it's kind of just 02:45.360 --> 02:48.270 the last step we are changing and then we still have to go 02:48.270 --> 02:50.520 through that redeployment process. 02:50.520 --> 02:54.240 So the other way that Scaffold can work is mode two 02:54.240 --> 02:56.790 which is to essentially take the updated files 02:56.790 --> 02:59.940 or the changes we made in our local React Project directory 02:59.940 --> 03:04.260 and just kind of magically inject them into our client pod. 03:04.260 --> 03:06.150 It will then be up to our client pod 03:06.150 --> 03:09.360 to somehow automatically update itself. 03:09.360 --> 03:10.500 So with mode two right here 03:10.500 --> 03:12.030 if we want to go through mode two 03:12.030 --> 03:14.610 we need to make sure that our client pod is running 03:14.610 --> 03:17.700 in such a mode where it's going to see these updated files 03:17.700 --> 03:20.220 and automatically update itself. 03:20.220 --> 03:22.290 We've already set up Create React App. 03:22.290 --> 03:24.360 Remember, Create React App is going to automatically 03:24.360 --> 03:25.740 refresh the change, or excuse me 03:25.740 --> 03:28.620 refresh the page anytime we change a file. 03:28.620 --> 03:31.080 We also set up our Node project as well 03:31.080 --> 03:33.510 the backend API server with Nodemon. 03:33.510 --> 03:35.160 So Nodemon watches for changes 03:35.160 --> 03:36.990 inside of our project directory. 03:36.990 --> 03:39.690 So right now our API server and the client pod 03:39.690 --> 03:43.620 will automatically refresh given this updated source code. 03:43.620 --> 03:45.930 So we currently have a project that's kind of well-suited 03:45.930 --> 03:47.013 for mode number two. 03:48.000 --> 03:50.730 Okay, so now we've got an overview of what Scaffold does. 03:50.730 --> 03:52.620 Let's start to go through the installation process 03:52.620 --> 03:53.613 in the next video.