NOTE This file was generated by Descript 1 00:00:00,240 --> 00:00:04,200 Hi guys, and welcome back. 2 00:00:04,410 --> 00:00:08,870 In this video, we're going to be creating a few files that Heroku needs in order to 3 00:00:08,870 --> 00:00:11,810 know what to run when we give it our code. 4 00:00:12,530 --> 00:00:16,490 The first thing it needs is it needs to know what Python version or even what 5 00:00:16,490 --> 00:00:19,040 language to use when it looks at our code. 6 00:00:19,310 --> 00:00:21,950 So we need to tell it that we're using Python and we need to 7 00:00:21,950 --> 00:00:23,480 tell it the version of Python. 8 00:00:24,020 --> 00:00:28,000 We do that with a file called runtime.txt. 9 00:00:28,710 --> 00:00:31,980 When we're deploying in Heroku, it's very important that this file name is 10 00:00:31,980 --> 00:00:35,440 exactly as I have typed it: runtime.txt. 11 00:00:35,850 --> 00:00:42,100 And in here, all in lowercase, we're going to put python dash 3 dot 9 dot 0. 12 00:00:42,400 --> 00:00:45,303 And that's it, we're just going to leave this as that. 13 00:00:45,483 --> 00:00:49,863 And when Heroku reads this file, which it will do immediately, when we give 14 00:00:49,863 --> 00:00:54,333 it our code, it will know that we are dealing here with a Python app and the 15 00:00:54,333 --> 00:00:58,743 Python version that it should use when it's running our code is Python 3.9. 16 00:00:59,703 --> 00:01:03,303 I'm going to leave a link in the resources section of this lecture for some other 17 00:01:03,303 --> 00:01:08,043 values that you can put in runtime.txt if you don't want to use Python 3.9. 18 00:01:08,546 --> 00:01:11,036 Now that we've got that we need something else. 19 00:01:11,426 --> 00:01:14,696 We need to tell Heroku how to run our app. 20 00:01:15,193 --> 00:01:19,183 Normally, when we run our app here in the terminal, we use flask run after 21 00:01:19,183 --> 00:01:22,963 activating the virtual environment, but Heroku is not going to do that. 22 00:01:23,828 --> 00:01:28,448 Instead of Heroku needs to rely on another library to run our code. 23 00:01:29,018 --> 00:01:32,168 So the first thing we're going to do, is we're going to add that other 24 00:01:32,168 --> 00:01:34,838 library to our requirements.txt file. 25 00:01:35,168 --> 00:01:37,108 And that is gunicorn. 26 00:01:37,798 --> 00:01:42,908 gunicorn is a library that will run our flask app for us, and it will 27 00:01:42,908 --> 00:01:46,908 add a few optimizations like the ability to run in multiple processes 28 00:01:47,178 --> 00:01:49,338 and run it in a different way. 29 00:01:49,788 --> 00:01:52,758 I'm not going to get into a lot of detail as to how it works, because 30 00:01:52,758 --> 00:01:57,558 it is quite complicated, but just know that Heroku can't use flask run 31 00:01:57,708 --> 00:02:01,648 as we have been doing it, it needs to use something else like gunicorn. 32 00:02:01,848 --> 00:02:04,338 And there's a few other options that we could use as well but 33 00:02:04,338 --> 00:02:06,078 gunicorn is the simplest one. 34 00:02:06,580 --> 00:02:11,430 So when we have installed gunicorn in Heroku, it will be able to use 35 00:02:11,430 --> 00:02:13,300 gunicorn to run our flask app. 36 00:02:13,990 --> 00:02:18,130 However, and this is an important point, if you are using Windows 37 00:02:18,370 --> 00:02:23,560 on your local development machine, like I am doing here, you cannot use 38 00:02:23,600 --> 00:02:26,470 gunicorn to run the flask app yourself. 39 00:02:26,920 --> 00:02:34,030 So if we do pip install gunicorn, this will work even if you're on Windows, but 40 00:02:34,060 --> 00:02:39,700 when you try to use gunicorn to run your flask app, that won't work. But that's 41 00:02:39,700 --> 00:02:43,540 okay because when we're coding here on our computer, we can still use flask run 42 00:02:43,540 --> 00:02:45,280 and that will still work fine, no problem. 43 00:02:45,626 --> 00:02:49,586 It is just when we give the code to Heroku that each we'll useg unicorn. 44 00:02:49,976 --> 00:02:53,666 If you're using Mac or Linux, you can use gunicorn in here 45 00:02:53,666 --> 00:02:54,946 and that will be fine as well. 46 00:02:55,550 --> 00:03:00,470 The next thing you have to do is create a file that will tell Heroku what command 47 00:03:00,500 --> 00:03:02,690 to run in order to execute our app. 48 00:03:03,615 --> 00:03:08,505 We were doing flask run, Heroku's going to use gunicorn, and the command 49 00:03:08,505 --> 00:03:11,865 itself goes in a file called Procfile. 50 00:03:12,225 --> 00:03:14,715 Make sure that this is not Procfile dot txt. 51 00:03:14,715 --> 00:03:16,175 It's just Procfile. 52 00:03:16,578 --> 00:03:20,208 In here we have to type web and then a colon, and then we're 53 00:03:20,208 --> 00:03:24,288 going to type out the command that Heroku will use, which is gunicorn. 54 00:03:24,768 --> 00:03:29,808 And then it in quotation marks app, colon create app just like that. 55 00:03:30,438 --> 00:03:32,628 So let me just break this down for you guys. 56 00:03:33,108 --> 00:03:37,158 What's happening here is we're telling Heroku that we are working on a web 57 00:03:37,158 --> 00:03:41,028 app and therefore, whatever this produces is something that is going 58 00:03:41,028 --> 00:03:44,448 to be connected to the internet so that other people can access it. 59 00:03:44,628 --> 00:03:47,238 That is what the web part of this line does. 60 00:03:47,298 --> 00:03:49,638 It tells Heroku we're using its web stack. 61 00:03:50,478 --> 00:03:53,808 gunicorn is the name of the application that Heroku will install 62 00:03:54,228 --> 00:03:56,635 from the requirements txt file. 63 00:03:56,635 --> 00:04:01,180 And this year is an argument to gunicorn that tells it which app to run. 64 00:04:01,660 --> 00:04:07,570 We're getting the app.py file and inside it, we're running the create_app function. 65 00:04:08,080 --> 00:04:11,710 And that is what's going to give us the app that gunicorn we run. 66 00:04:12,730 --> 00:04:14,950 It's important that this is the inside quotation marks because 67 00:04:14,950 --> 00:04:18,700 otherwise this colon there and these brackets there will cause problems. 68 00:04:18,940 --> 00:04:21,100 So just make sure to put it exactly like that. 69 00:04:21,700 --> 00:04:24,490 The last thing we have to do to prepare our app for Heroku, if you haven't 70 00:04:24,490 --> 00:04:29,710 done so already is to make sure to put your MongoDB URI here, inside these 71 00:04:29,710 --> 00:04:33,010 quotation marks, including your username and password and everything else. 72 00:04:34,015 --> 00:04:37,075 What we're going to do next, in the next few videos is we're going to put this 73 00:04:37,075 --> 00:04:39,325 code online so that Heroku can access it. 74 00:04:39,685 --> 00:04:43,915 And in a later video, we're going to explore how to hide this from the 75 00:04:43,915 --> 00:04:48,835 code so that it's not accessible to anybody who reads this app code that's 76 00:04:48,835 --> 00:04:52,255 because some people will be able to read the app code and I'll explain 77 00:04:52,255 --> 00:04:54,385 how that can happen in the next video. 78 00:04:54,955 --> 00:04:55,315 All right. 79 00:04:55,495 --> 00:04:56,665 Thanks for joining me in this one. 80 00:04:56,755 --> 00:04:58,165 And I'll see you in the next one.