1 00:00:00,395 --> 00:00:02,418 - [Instructor] Hi and welcome back to the course. 2 00:00:02,418 --> 00:00:06,585 In this video we're going to set up UWSGI in our server. 3 00:00:07,806 --> 00:00:11,269 What we've done up till now is download our application 4 00:00:11,269 --> 00:00:13,480 from GitHub, our rest api. 5 00:00:13,480 --> 00:00:16,958 We've installed python and some development 6 00:00:16,958 --> 00:00:18,755 libraries that we've needed. 7 00:00:18,755 --> 00:00:21,669 Then we've also installed virtual environment, 8 00:00:21,669 --> 00:00:23,202 and we've created a virtual end, 9 00:00:23,202 --> 00:00:26,035 and we've installed the requirements.txt file 10 00:00:26,035 --> 00:00:28,389 in our application folder. 11 00:00:28,389 --> 00:00:31,830 So just to recap, what we did was we created 12 00:00:31,830 --> 00:00:35,997 a slash/var/www/html/items-rest folder, 13 00:00:37,869 --> 00:00:41,692 and in this folder, we downloaded from Git, 14 00:00:41,692 --> 00:00:45,377 our respsirtory, and we've created the log folder, 15 00:00:45,377 --> 00:00:47,745 we created the virtual environment folder, 16 00:00:47,745 --> 00:00:49,951 and we setup a new virtual environment 17 00:00:49,951 --> 00:00:52,463 using Python 3.5, and then we installed 18 00:00:52,463 --> 00:00:55,376 the requirements.txt file, which includes 19 00:00:55,376 --> 00:00:57,299 everything that we need. 20 00:00:57,299 --> 00:01:00,991 This means that the stuff we've got here 21 00:01:00,991 --> 00:01:03,502 is nearly ready to be used. 22 00:01:03,502 --> 00:01:07,156 The only last thing we have to change is a UWSGI 23 00:01:07,156 --> 00:01:08,898 and .ini file. 24 00:01:08,898 --> 00:01:11,358 And we're going to do that in a moment. 25 00:01:11,358 --> 00:01:14,804 First, we're going to create what's called 26 00:01:14,804 --> 00:01:17,115 an open to service. 27 00:01:17,115 --> 00:01:21,121 And a service is something that you can tell Ubuntu 28 00:01:21,121 --> 00:01:24,907 to run when the computer starts, when a server starts, 29 00:01:24,907 --> 00:01:27,772 and you can tell it to restart when it crashes 30 00:01:27,772 --> 00:01:28,721 and things like that. 31 00:01:28,721 --> 00:01:33,536 So essentially, a service is a descriptor of a programme, 32 00:01:33,536 --> 00:01:36,647 and you can, essentially, set the service 33 00:01:36,647 --> 00:01:39,076 to run and restart, and things like that. 34 00:01:39,076 --> 00:01:41,907 In addition, a service also lets you do things 35 00:01:41,907 --> 00:01:46,074 like set environment variables before the service runs, 36 00:01:47,302 --> 00:01:49,646 which is gonna be very useful. 37 00:01:49,646 --> 00:01:52,315 So let's get started creating this service, 38 00:01:52,315 --> 00:01:54,492 and I will explain as we go along 39 00:01:54,492 --> 00:01:57,026 exactly how things work and when we're finished 40 00:01:57,026 --> 00:01:59,626 in developing this service, or creating this service. 41 00:01:59,626 --> 00:02:04,365 And you'll understand a bit more why it's interesting. 42 00:02:04,365 --> 00:02:07,615 So what we're going to do is a sudo vi, 43 00:02:08,499 --> 00:02:10,943 and remember, this is going to open up a text editor, 44 00:02:10,943 --> 00:02:13,695 which is called Vi, and we're gonna do this command 45 00:02:13,695 --> 00:02:15,112 as the root user. 46 00:02:17,313 --> 00:02:21,480 And the file we want to edit is /etc/systemd 47 00:02:22,388 --> 00:02:26,017 for system demon, which is essentially just a programme 48 00:02:26,017 --> 00:02:29,755 that runs and looks at things inside this folder, 49 00:02:29,755 --> 00:02:33,922 /system/UWSGI_items_rest.service. 50 00:02:36,423 --> 00:02:39,052 That's important, the .service at the end. 51 00:02:39,052 --> 00:02:43,282 All we're doing is creating a new text file, essentially. 52 00:02:43,282 --> 00:02:47,449 Inside this particular folder /etc/systemd/system, 53 00:02:48,533 --> 00:02:52,250 and Ubuntu, when we create a file which ends 54 00:02:52,250 --> 00:02:55,991 in .service and is inside this folder, 55 00:02:55,991 --> 00:02:59,958 it starts knowing that this is a service and that 56 00:02:59,958 --> 00:03:03,958 it can run as a service using the system controller, 57 00:03:03,958 --> 00:03:06,373 and we're gonna look at how they compare. 58 00:03:06,373 --> 00:03:09,076 So now here it asks for my password, which I'm going 59 00:03:09,076 --> 00:03:12,388 to put in, and then as you can see, we create a ini file. 60 00:03:12,388 --> 00:03:16,978 Down here at the bottom you can see that Vi test editor 61 00:03:16,978 --> 00:03:19,307 is telling us this is a new file. 62 00:03:19,307 --> 00:03:21,403 So now that I have a few parts 63 00:03:21,403 --> 00:03:23,947 to creating an Ubuntu service, but it's really 64 00:03:23,947 --> 00:03:26,520 a quite self-explanatory as we go along. 65 00:03:26,520 --> 00:03:29,648 And the first part is a unit, and we have to type, 66 00:03:29,648 --> 00:03:32,092 of course, the I key first. 67 00:03:32,092 --> 00:03:35,805 We're going to insert mode, and then inside square 68 00:03:35,805 --> 00:03:38,479 brackets, we're gonna type unit with a capital U. 69 00:03:38,479 --> 00:03:43,082 What this is a section, and a section of a service 70 00:03:43,082 --> 00:03:46,940 allows us to define some properties of the service. 71 00:03:46,940 --> 00:03:49,421 And one of the properties we're going to define 72 00:03:49,421 --> 00:03:52,923 within this unit section is the description 73 00:03:52,923 --> 00:03:55,088 of the service, and the way we define a description 74 00:03:55,088 --> 00:03:59,254 is we see description with a capital D, equals, 75 00:03:59,254 --> 00:04:03,421 and then we can type in a description of our service. 76 00:04:04,489 --> 00:04:06,620 This is going to be useful, for example, 77 00:04:06,620 --> 00:04:08,211 when we run the service. 78 00:04:08,211 --> 00:04:10,653 It's going to say we're running this service 79 00:04:10,653 --> 00:04:13,725 that we are describing, and that's going to be useful 80 00:04:13,725 --> 00:04:17,257 if an error happens, we can then go back and look 81 00:04:17,257 --> 00:04:18,485 for this description. 82 00:04:18,485 --> 00:04:22,152 It will appear in all the logs and things like that. 83 00:04:22,152 --> 00:04:25,751 So something that describes the service is useful. 84 00:04:25,751 --> 00:04:28,918 I'm going to call it UWSGI items rest. 85 00:04:30,865 --> 00:04:32,274 I think it's fairly explanatory. 86 00:04:32,274 --> 00:04:34,283 We've got an items rest api. 87 00:04:34,283 --> 00:04:37,584 This is a UWSGI service that we're going to be running, 88 00:04:37,584 --> 00:04:40,554 so whenever we see this in the logs later on, 89 00:04:40,554 --> 00:04:43,354 we're gonna know that this is what this means. 90 00:04:43,354 --> 00:04:44,854 This service here. 91 00:04:46,071 --> 00:04:48,514 The next section is service. 92 00:04:48,514 --> 00:04:51,702 Once again, inside square brackets with a capital S, 93 00:04:51,702 --> 00:04:55,932 we'll type service, and now we've defined the unit section. 94 00:04:55,932 --> 00:04:59,043 Whenever the system controller runs this service, 95 00:04:59,043 --> 00:05:01,547 it's gonna look at the unit section, find the description, 96 00:05:01,547 --> 00:05:02,823 and use that description. 97 00:05:02,823 --> 00:05:04,920 Then it's gonna look at the service section 98 00:05:04,920 --> 00:05:06,698 and it's gonna look at all the properties 99 00:05:06,698 --> 00:05:07,982 we're gonna define here. 100 00:05:07,982 --> 00:05:11,431 It's going to run the service using these properties. 101 00:05:11,431 --> 00:05:13,896 The first property that we're going 102 00:05:13,896 --> 00:05:16,609 to define is environment. 103 00:05:16,609 --> 00:05:19,565 And remember, you put a capital E, and what this does 104 00:05:19,565 --> 00:05:22,248 is it allows us to define an environment variable 105 00:05:22,248 --> 00:05:25,622 right before the service starts. 106 00:05:25,622 --> 00:05:29,333 Remember, this service is going to run UWSGI, 107 00:05:29,333 --> 00:05:32,666 and UWSGI is going to run our Flask app. 108 00:05:33,955 --> 00:05:38,122 So what environment variable do we need in our Flask app? 109 00:05:50,245 --> 00:05:51,511 I hope you got that. 110 00:05:51,511 --> 00:05:55,372 The environment variable we need is DATABASE_URL, 111 00:05:55,372 --> 00:05:57,965 and that's because, if you remember from the last section 112 00:05:57,965 --> 00:06:02,654 on hero deployments, we changed our app, our api, 113 00:06:02,654 --> 00:06:05,635 to use a DATABASE_URL environment variable, 114 00:06:05,635 --> 00:06:07,445 and if you haven't done the last section, 115 00:06:07,445 --> 00:06:08,950 and I'll tell you now. 116 00:06:08,950 --> 00:06:11,209 Instead of sticking with SQL Lite, we're going 117 00:06:11,209 --> 00:06:14,768 to use Posher SQL, which you know, 118 00:06:14,768 --> 00:06:18,549 and instead of hard coding the URL in the code, 119 00:06:18,549 --> 00:06:21,100 we're going to be defining the URL 120 00:06:21,100 --> 00:06:23,061 inside this environment variable, 121 00:06:23,061 --> 00:06:26,186 but this is a variable that this server remembers, 122 00:06:26,186 --> 00:06:28,766 and then we're gonna tell our Python code 123 00:06:28,766 --> 00:06:31,232 to read this environment to find out 124 00:06:31,232 --> 00:06:35,146 what the DATABASE_URL is, and then it's gonna access 125 00:06:35,146 --> 00:06:37,128 the database on that URL. 126 00:06:37,128 --> 00:06:40,038 And that's better than putting in the code, 127 00:06:40,038 --> 00:06:42,350 because if we leave it in the code and people 128 00:06:42,350 --> 00:06:44,636 are gonna be able to look at the database 129 00:06:44,636 --> 00:06:48,999 username and password that we have defined. 130 00:06:48,999 --> 00:06:50,332 Not ideal, okay. 131 00:06:52,109 --> 00:06:55,707 So we're gonna say DATABASE_URL, equals, 132 00:06:55,707 --> 00:06:59,108 and here we go with the database URL for postgres, 133 00:06:59,108 --> 00:07:02,301 which is postgres://, 134 00:07:02,301 --> 00:07:03,772 this is necessary. 135 00:07:03,772 --> 00:07:04,787 You cannot skip this bit. 136 00:07:04,787 --> 00:07:09,214 And then we're going to type in our postgres user 137 00:07:09,214 --> 00:07:13,135 that we created using a create user earlier on 138 00:07:13,135 --> 00:07:16,762 in this section, which in my case, is Jose. 139 00:07:16,762 --> 00:07:19,264 Then we're gonna put the colon, and then we're going 140 00:07:19,264 --> 00:07:21,720 to put the password, which in my case is 1234. 141 00:07:21,720 --> 00:07:25,145 And you may have chosen a more secure password. 142 00:07:25,145 --> 00:07:28,645 Okay, so that's the user, colon, password, 143 00:07:30,019 --> 00:07:32,349 and then we're going to type in the at symbol, 144 00:07:32,349 --> 00:07:35,593 and where we're gonna put localhost. 145 00:07:35,593 --> 00:07:39,739 Localhost is a server that this programme is running on. 146 00:07:39,739 --> 00:07:42,253 So what this is going to do is it's going 147 00:07:42,253 --> 00:07:45,253 to try to access the postgres server 148 00:07:46,270 --> 00:07:48,960 running on the same server as the app, 149 00:07:48,960 --> 00:07:52,793 using the username Jose and the password 1234. 150 00:07:53,716 --> 00:07:56,061 This does means that we can access the postgres 151 00:07:56,061 --> 00:07:59,010 server on a different server if we have it setup, 152 00:07:59,010 --> 00:08:00,194 which we don't. 153 00:08:00,194 --> 00:08:01,847 But potentially, if you wanted to separate 154 00:08:01,847 --> 00:08:05,191 your postgres and your flash servers, you could do that 155 00:08:05,191 --> 00:08:06,231 and that would be fine. 156 00:08:06,231 --> 00:08:09,358 You will have to set the postgres to enable 157 00:08:09,358 --> 00:08:11,005 you to do that. 158 00:08:11,005 --> 00:08:13,896 Finally, after the local host, we're gonna put 159 00:08:13,896 --> 00:08:16,826 a colon again and 5432, which is the port 160 00:08:16,826 --> 00:08:19,056 that postgres was running on, as we saw 161 00:08:19,056 --> 00:08:20,995 earlier in this section. 162 00:08:20,995 --> 00:08:22,749 Okay, so looks a bit confusing. 163 00:08:22,749 --> 00:08:26,832 Username, colon, password, @ server, colon, port. 164 00:08:27,872 --> 00:08:31,420 Okay, so the server is local hosting now. 165 00:08:31,420 --> 00:08:33,956 Finally, at the very end, we're gonna put 166 00:08:33,956 --> 00:08:36,107 a forward slash and we're going to put Jose again. 167 00:08:36,107 --> 00:08:38,686 And now this is not the user, 168 00:08:38,686 --> 00:08:41,844 this is the database that we're accessing. 169 00:08:41,844 --> 00:08:44,893 So in my case, I've created a database called Jose 170 00:08:44,893 --> 00:08:47,595 to match my user, but potentially you could've created 171 00:08:47,595 --> 00:08:51,762 a database such as fullstack or rest.api, or something. 172 00:08:54,015 --> 00:08:56,029 Sorry, that was misspelt. 173 00:08:56,029 --> 00:08:58,032 So this is just the database you've created, 174 00:08:58,032 --> 00:09:00,714 and you must make sure that your Jose user 175 00:09:00,714 --> 00:09:03,124 has access to that database, which it most likely 176 00:09:03,124 --> 00:09:04,457 will be default. 177 00:09:05,880 --> 00:09:06,713 Now okay. 178 00:09:07,791 --> 00:09:10,178 That is the environment variable we're going to define. 179 00:09:10,178 --> 00:09:13,813 So right before running the Flask app, 180 00:09:13,813 --> 00:09:17,998 or the UWSGI app, we're just gonna run the Flask app. 181 00:09:17,998 --> 00:09:20,926 We're going to define this environment variable, 182 00:09:20,926 --> 00:09:22,471 and the server is going to know 183 00:09:22,471 --> 00:09:24,617 that this environment variable exists. 184 00:09:24,617 --> 00:09:26,962 Then our Python code is going to access it 185 00:09:26,962 --> 00:09:28,962 to retrieve this string. 186 00:09:35,651 --> 00:09:37,794 Next, we're going to type ExecStart. 187 00:09:37,794 --> 00:09:41,993 Notice how the E is capital and the S is capital? 188 00:09:41,993 --> 00:09:45,576 And this is what programme this service runs. 189 00:09:46,684 --> 00:09:50,881 Remember, a service descriptor is used to tell Ubuntu 190 00:09:50,881 --> 00:09:55,090 that this is a service that can be started 191 00:09:55,090 --> 00:09:57,071 when the computer or the server starts, 192 00:09:57,071 --> 00:09:59,627 it can be restarted if it crashes, and things like that. 193 00:09:59,627 --> 00:10:01,586 And Ubuntu will take care of that for us, 194 00:10:01,586 --> 00:10:05,255 but we have to tell it what programme we want 195 00:10:05,255 --> 00:10:06,997 the service to run, and in this case, we want 196 00:10:06,997 --> 00:10:09,997 to tell it to run the UWSGI programme, 197 00:10:11,448 --> 00:10:14,961 which is then going to run our Flask app. 198 00:10:14,961 --> 00:10:19,426 So the way we tell it is by using the normal Unix 199 00:10:19,426 --> 00:10:21,289 notation for running a programme. 200 00:10:21,289 --> 00:10:23,208 The first thing we do is we tell it the programme name. 201 00:10:23,208 --> 00:10:27,375 So /var/www/html/items-rest/venv/bin/UWSGI. 202 00:10:32,302 --> 00:10:35,843 So when we've installed UWSGI, that has created 203 00:10:35,843 --> 00:10:39,093 a UWSGI executable file that we can run 204 00:10:40,420 --> 00:10:42,549 inside the virtual environment. 205 00:10:42,549 --> 00:10:46,467 So we have our project folder, the virtual 206 00:10:46,467 --> 00:10:49,668 environment folder, and then the binaries folder, 207 00:10:49,668 --> 00:10:50,801 the bin folder. 208 00:10:50,801 --> 00:10:52,296 We've got UWSGI. 209 00:10:52,296 --> 00:10:57,192 We can run UWSGI, and that starts the UWSGI process. 210 00:10:57,192 --> 00:11:00,211 Then we're going to tell it --master, 211 00:11:00,211 --> 00:11:02,083 after a space, remember. 212 00:11:02,083 --> 00:11:03,904 Space there and then --master, and what this does 213 00:11:03,904 --> 00:11:06,332 is it tells it to use a master process. 214 00:11:06,332 --> 00:11:09,982 Master process is a way that UWSGI has of keeping 215 00:11:09,982 --> 00:11:12,894 track of other processes in case we use more than one. 216 00:11:12,894 --> 00:11:17,167 So it can restart them if they crash and if they get blocked 217 00:11:17,167 --> 00:11:19,098 and things like that. 218 00:11:19,098 --> 00:11:21,634 Then we're going to use --emperor. 219 00:11:21,634 --> 00:11:25,801 Emperor, which is essentially a controller as well. 220 00:11:28,944 --> 00:11:31,903 And then we're going to tell it the configuration file 221 00:11:31,903 --> 00:11:36,070 for UWSGI, which is in /var/www/html/items-rest/UWSGI.ini. 222 00:11:41,360 --> 00:11:44,263 And we created this in the last section and in 223 00:11:44,263 --> 00:11:46,463 hero deployments as well. 224 00:11:46,463 --> 00:11:49,635 And it's got, essentially, how to run the Flask app. 225 00:11:49,635 --> 00:11:51,584 That's what this file contains. 226 00:11:51,584 --> 00:11:55,071 It tells UWSGI what Python code it 227 00:11:55,071 --> 00:11:57,969 is meant to interact with. 228 00:11:57,969 --> 00:12:01,437 Then we're going to say --die-on-term, 229 00:12:01,437 --> 00:12:03,699 and that is essentially when we terminate 230 00:12:03,699 --> 00:12:05,315 the UWSGI process. 231 00:12:05,315 --> 00:12:08,225 That's going to take the Python code as well. 232 00:12:08,225 --> 00:12:10,269 And so it doesn't keep running in the background 233 00:12:10,269 --> 00:12:12,186 without doing anything. 234 00:12:13,111 --> 00:12:15,944 Finally, we're going to say --uid, 235 00:12:17,768 --> 00:12:20,705 and then I'm going to type in Jose, which is my username. 236 00:12:20,705 --> 00:12:22,729 You should type your own username here. 237 00:12:22,729 --> 00:12:26,896 And what this is please run the UWSGI process as Jose. 238 00:12:28,416 --> 00:12:31,893 Remember, in the past, we accessed the process 239 00:12:31,893 --> 00:12:34,813 as the postgres user by doing something 240 00:12:34,813 --> 00:12:37,230 like psudeo -you -I postgres. 241 00:12:38,396 --> 00:12:40,089 And this is essentially gonna do the same, 242 00:12:40,089 --> 00:12:42,957 but it's going to run the UWSGI process 243 00:12:42,957 --> 00:12:47,632 as the Jose user, which is good because Jose user 244 00:12:47,632 --> 00:12:51,034 owns this folder here, so the user has access 245 00:12:51,034 --> 00:12:53,613 to doing everything inside this folder. 246 00:12:53,613 --> 00:12:56,963 Now similarly, GID for the group ID, 247 00:12:56,963 --> 00:12:58,905 which is also going to be Jose. 248 00:12:58,905 --> 00:13:00,615 So we want to make sure that both the user 249 00:13:00,615 --> 00:13:04,365 and the group match the owner of this folder. 250 00:13:06,612 --> 00:13:09,571 And finally, we're gonna tell it the log folder. 251 00:13:09,571 --> 00:13:10,457 So we're gonna say 252 00:13:10,457 --> 00:13:14,624 logto/var/www/html/items-rest/log/emperor.log. 253 00:13:20,204 --> 00:13:21,687 And what this is going to do is it's going 254 00:13:21,687 --> 00:13:24,238 to tell it where to write the log files 255 00:13:24,238 --> 00:13:26,571 for the emperor and process. 256 00:13:31,475 --> 00:13:32,487 That's it. 257 00:13:32,487 --> 00:13:37,064 That's the XX start and sort of property, and now 258 00:13:37,064 --> 00:13:40,338 whenever we run this service using the system controller, 259 00:13:40,338 --> 00:13:42,961 it is going to run this command there. 260 00:13:42,961 --> 00:13:45,689 Before running that command, it's going to make sure 261 00:13:45,689 --> 00:13:48,004 that this environment variable exists. 262 00:13:48,004 --> 00:13:50,784 And so after running this command, our Python 263 00:13:50,784 --> 00:13:53,622 code will be able to access the database URL 264 00:13:53,622 --> 00:13:55,705 and environment variable. 265 00:13:56,787 --> 00:13:59,241 Finally, we're going to say restart=always, 266 00:13:59,241 --> 00:14:01,289 and that's just gonna mean if the process 267 00:14:01,289 --> 00:14:04,503 crashes or stopped, then the assessment controller 268 00:14:04,503 --> 00:14:07,949 is going to restart the process so it's not dead 269 00:14:07,949 --> 00:14:10,884 for a long period of time. 270 00:14:10,884 --> 00:14:13,146 Finally, we're going to give it a kill signal, 271 00:14:13,146 --> 00:14:17,156 which his SIGQUIT, and this is reasonably complicated 272 00:14:17,156 --> 00:14:20,304 and Unix set of terminology. 273 00:14:20,304 --> 00:14:23,829 There are many different ways to terminate a process, 274 00:14:23,829 --> 00:14:27,996 but SEGQUIT is one of them, and that doesn't force quit. 275 00:14:30,680 --> 00:14:34,662 So it tells it to exit, then it will shut down gracefully 276 00:14:34,662 --> 00:14:38,280 without losing data, things like that. 277 00:14:38,280 --> 00:14:41,030 And it's good to have that there. 278 00:14:43,458 --> 00:14:47,625 We're going to type Type=notify, and notifyAccess=all. 279 00:14:49,882 --> 00:14:53,050 So these are just the notification parameters 280 00:14:53,050 --> 00:14:54,467 for this service. 281 00:14:56,882 --> 00:15:00,838 Finally, we're going to have a last section called instal. 282 00:15:00,838 --> 00:15:03,709 And this is not a very good name for this section. 283 00:15:03,709 --> 00:15:06,032 And also not a very good name for the property, 284 00:15:06,032 --> 00:15:08,615 WantedBy=mult-user.target. 285 00:15:09,658 --> 00:15:11,825 And as weird as it sounds, 286 00:15:12,861 --> 00:15:15,223 what this does is it allows us to start 287 00:15:15,223 --> 00:15:18,306 the service when the server boots up, 288 00:15:19,545 --> 00:15:23,588 which is a rather weird naming convention there, 289 00:15:23,588 --> 00:15:26,303 but never-the-less, that's what that does. 290 00:15:26,303 --> 00:15:29,803 So now we've got our service created here, 291 00:15:31,403 --> 00:15:35,096 and remember every character counts, and every space 292 00:15:35,096 --> 00:15:38,107 and everything that we have typed here. 293 00:15:38,107 --> 00:15:40,502 So have a really close look at this 294 00:15:40,502 --> 00:15:43,187 and make sure that you've got it exactly like that. 295 00:15:43,187 --> 00:15:45,908 You should only change your username and password 296 00:15:45,908 --> 00:15:48,825 and database, and also UID and GID. 297 00:15:52,419 --> 00:15:55,041 The rest should stay the same. 298 00:15:55,041 --> 00:15:58,941 And when you're done, press the escape key 299 00:15:58,941 --> 00:16:01,691 and call on WQ to write and quit. 300 00:16:02,722 --> 00:16:05,305 And that's the service created. 301 00:16:06,597 --> 00:16:08,930 So that is pretty fantastic. 302 00:16:11,990 --> 00:16:14,624 There is one last thing that we have to do as well 303 00:16:14,624 --> 00:16:17,374 which is, as I mentioned earlier, 304 00:16:18,419 --> 00:16:21,296 change the UWSGI.ini file. 305 00:16:21,296 --> 00:16:23,344 So what we're going to do is we're going 306 00:16:23,344 --> 00:16:24,943 to delete all of that. 307 00:16:24,943 --> 00:16:27,290 And it's here, because this was the Horoku 308 00:16:27,290 --> 00:16:29,285 UWSGI.ini configuration. 309 00:16:29,285 --> 00:16:32,040 And the way to delete things in Vi 310 00:16:32,040 --> 00:16:35,707 is to press the D key, followed by shift, G. 311 00:16:37,441 --> 00:16:39,508 And that deletes everything. 312 00:16:39,508 --> 00:16:42,144 Then we're going to press the I key to go into insert mode, 313 00:16:42,144 --> 00:16:44,513 and we're going to write a few things here, 314 00:16:44,513 --> 00:16:46,543 so please bare with me. 315 00:16:46,543 --> 00:16:48,817 Once again, a section called UWSGI. 316 00:16:48,817 --> 00:16:50,346 That is going to be the only section 317 00:16:50,346 --> 00:16:51,846 in this .ini file. 318 00:16:54,143 --> 00:16:56,664 And we're going to start by finding the base folder 319 00:16:56,664 --> 00:16:59,247 where the UWSGI programme exists. 320 00:17:02,488 --> 00:17:06,645 And that's just in the base folder of our app. 321 00:17:06,645 --> 00:17:08,745 Then we're going to tell it which file 322 00:17:08,745 --> 00:17:12,912 to find the app in, which could be our app.py file, 323 00:17:14,105 --> 00:17:17,605 but it's in fact going to be our run file, 324 00:17:18,597 --> 00:17:20,249 or maybe you didn't follow the last section, 325 00:17:20,249 --> 00:17:23,323 but in the last section, the run file was created 326 00:17:23,323 --> 00:17:25,564 to make sure that the database was initialised 327 00:17:25,564 --> 00:17:29,231 before the app was ran, so that's important. 328 00:17:30,512 --> 00:17:34,679 And the module that we're importing is the same one. 329 00:17:36,090 --> 00:17:37,588 App. 330 00:17:37,588 --> 00:17:41,902 And what this does is that this loads that variable there. 331 00:17:41,902 --> 00:17:44,935 So the module we're importing is the app module, 332 00:17:44,935 --> 00:17:47,018 which is the run.py file. 333 00:17:49,173 --> 00:17:53,006 And UWSGI is gonna use this variable later on. 334 00:17:54,600 --> 00:17:57,517 Okay, the home of the UWSGI process 335 00:17:59,526 --> 00:18:04,263 is the base folder /venv, because it lives 336 00:18:04,263 --> 00:18:07,214 inside the virtual environment UWSGI. 337 00:18:07,214 --> 00:18:09,785 And apologies, this should not be a dollar, 338 00:18:09,785 --> 00:18:11,957 it should be a percent symbol there. 339 00:18:11,957 --> 00:18:16,124 That's how we used previously defined variables like that. 340 00:18:17,102 --> 00:18:18,380 The Python path. 341 00:18:18,380 --> 00:18:22,151 This is a pretty funny environment variable as well, 342 00:18:22,151 --> 00:18:24,845 but the Python path essentially defines 343 00:18:24,845 --> 00:18:28,115 where your Python project beings. 344 00:18:28,115 --> 00:18:31,433 So what is the root folder of your Python project? 345 00:18:31,433 --> 00:18:35,100 And in this case, it's also the base folder. 346 00:18:36,521 --> 00:18:40,688 Now the socket file is in the base folder /socket.sock. 347 00:18:43,638 --> 00:18:46,147 Don't know if you guys remember that we defined 348 00:18:46,147 --> 00:18:50,503 this earlier on in the section and the socket.sock file 349 00:18:50,503 --> 00:18:53,751 is what's going to allow communication 350 00:18:53,751 --> 00:18:57,549 between the UWSGI process and engine.exe. 351 00:18:57,549 --> 00:19:01,122 And so it's going to be a file there that allows 352 00:19:01,122 --> 00:19:02,705 that communication. 353 00:19:03,803 --> 00:19:07,220 This socket must have permissions of 777. 354 00:19:08,544 --> 00:19:11,948 So we are going to change the permissions 355 00:19:11,948 --> 00:19:15,768 of the socket to 777, and I'm not gonna get into 356 00:19:15,768 --> 00:19:19,187 exactly all the Unix permissions, but just remember 357 00:19:19,187 --> 00:19:23,444 777 means that anybody can access this socket file. 358 00:19:23,444 --> 00:19:26,313 Any user in the system and any group in the system, 359 00:19:26,313 --> 00:19:28,047 and access this socket file. 360 00:19:28,047 --> 00:19:29,742 That's what this means. 361 00:19:29,742 --> 00:19:32,099 And that's important to make sure that engine.exe 362 00:19:32,099 --> 00:19:34,959 can access the socket file. 363 00:19:34,959 --> 00:19:38,065 Okay, then we're going to tell it the number of processes 364 00:19:38,065 --> 00:19:40,223 that we want, and I'm going to say eight 365 00:19:40,223 --> 00:19:42,637 and although that may be a bit high depending 366 00:19:42,637 --> 00:19:45,543 on what sort of droplet we're using. 367 00:19:45,543 --> 00:19:48,929 And the processes is a matter of being nominated, 368 00:19:48,929 --> 00:19:51,263 and if things go well or they act too slow, 369 00:19:51,263 --> 00:19:53,035 you can try and play around with that. 370 00:19:53,035 --> 00:19:55,077 It's not something that I can normally change. 371 00:19:55,077 --> 00:19:59,196 And threads, I'm going to give it eight as well. 372 00:19:59,196 --> 00:20:03,208 So each process is going to have eight threads, and again, 373 00:20:03,208 --> 00:20:04,554 this is something that you can play with. 374 00:20:04,554 --> 00:20:06,351 It depends on the process that you're using. 375 00:20:06,351 --> 00:20:10,767 Many of these solution boxes, this may be a bit too high. 376 00:20:10,767 --> 00:20:12,350 But never-the-less. 377 00:20:13,427 --> 00:20:15,615 Then we're also going to define the harakiri, 378 00:20:15,615 --> 00:20:18,011 which is going to be 15 seconds, 379 00:20:18,011 --> 00:20:20,475 and the harakiri comes from the Japanese thing 380 00:20:20,475 --> 00:20:24,012 that the samurais did, which is essentially kill themselves 381 00:20:24,012 --> 00:20:26,511 if they did something wrong, and here 382 00:20:26,511 --> 00:20:27,775 it means the same thing. 383 00:20:27,775 --> 00:20:31,165 If one of these threads gets blocked 384 00:20:31,165 --> 00:20:32,918 or has an error and it shuts down, 385 00:20:32,918 --> 00:20:35,352 then after 15 seconds, we're going to destroy 386 00:20:35,352 --> 00:20:37,391 the thread and create another one. 387 00:20:37,391 --> 00:20:40,859 And the emperor, the UWSGI emperor is going 388 00:20:40,859 --> 00:20:43,109 to be responsible for that. 389 00:20:44,663 --> 00:20:47,688 Finally, we're gonna define a callable, 390 00:20:47,688 --> 00:20:50,203 which is going to be app. 391 00:20:50,203 --> 00:20:53,203 And this app is not the file app.py. 392 00:20:54,040 --> 00:20:58,026 This is the variable app that is imported 393 00:20:58,026 --> 00:20:59,609 in the run.py file. 394 00:21:00,541 --> 00:21:02,734 So what UWSGI is gonna see, 395 00:21:02,734 --> 00:21:05,451 it's going to get this module and it's going 396 00:21:05,451 --> 00:21:07,531 to find this variable in the module 397 00:21:07,531 --> 00:21:09,972 and it's going to run that Flask app. 398 00:21:09,972 --> 00:21:12,472 And so that's important there. 399 00:21:13,775 --> 00:21:16,080 And also we want to define a place 400 00:21:16,080 --> 00:21:18,247 to log the Python app out. 401 00:21:19,799 --> 00:21:21,730 So this is exactly what you saw 402 00:21:21,730 --> 00:21:24,135 in your terminal when you ran your Flask app, 403 00:21:24,135 --> 00:21:26,276 such as the request coming in, 404 00:21:26,276 --> 00:21:28,126 and the errors and things like that. 405 00:21:28,126 --> 00:21:29,959 We want to log them somewhere, and where we want 406 00:21:29,959 --> 00:21:34,126 to log them is /var/www/html/items-rest/log 407 00:21:37,493 --> 00:21:39,300 as the log folder we created earlier, 408 00:21:39,300 --> 00:21:41,654 and then %n.log. 409 00:21:41,654 --> 00:21:45,237 And %n is basically going to be UWSGI. 410 00:21:46,596 --> 00:21:50,679 It's going to log the Python output to UWSGI.log. 411 00:21:51,863 --> 00:21:53,196 Okay, that's it. 412 00:21:54,727 --> 00:21:59,125 So press the escape file and :wq will write and quit, 413 00:21:59,125 --> 00:22:00,916 and remember what we've done here 414 00:22:00,916 --> 00:22:04,666 is told the UWSGI how to run the Python code. 415 00:22:06,784 --> 00:22:07,617 Okay. 416 00:22:08,829 --> 00:22:12,267 And finally, we can startup our Flask app 417 00:22:12,267 --> 00:22:15,502 by doing sudo system controller, 418 00:22:15,502 --> 00:22:18,502 system ctl, start, UWSGI_items_rest. 419 00:22:21,206 --> 00:22:23,542 This here is the name of the service 420 00:22:23,542 --> 00:22:26,328 that we defined earlier, and that is going 421 00:22:26,328 --> 00:22:30,760 to go into the service, run the XX start command, 422 00:22:30,760 --> 00:22:33,298 which is going to run UWSGI, which is going 423 00:22:33,298 --> 00:22:35,756 to look at the UWSGI.ini file, 424 00:22:35,756 --> 00:22:37,743 which is going to run the Flask app and create 425 00:22:37,743 --> 00:22:40,050 the socket file, which is going to communicate 426 00:22:40,050 --> 00:22:42,588 with engine.exe to route the requests 427 00:22:42,588 --> 00:22:44,251 to our Flask app. 428 00:22:44,251 --> 00:22:47,508 And so hopefully, all that makes sense. 429 00:22:47,508 --> 00:22:50,388 And once again, we need the password in here. 430 00:22:50,388 --> 00:22:51,802 And that's it running. 431 00:22:51,802 --> 00:22:54,536 Now the first thing to do, once we do this, 432 00:22:54,536 --> 00:22:57,619 is to go into the log folder and look 433 00:22:58,729 --> 00:23:00,535 at the UWSGI log. 434 00:23:00,535 --> 00:23:02,479 Then we're going to go down to the very bottom 435 00:23:02,479 --> 00:23:06,418 and see if things are working fine, or if there's a problem. 436 00:23:06,418 --> 00:23:09,584 As you can see, we've spawned the UWSGI processes, 437 00:23:09,584 --> 00:23:12,654 but there's nothing else left down here, so we may have 438 00:23:12,654 --> 00:23:14,599 accessed this a bit earlier. 439 00:23:14,599 --> 00:23:16,808 I'm going to type :q to exit, 440 00:23:16,808 --> 00:23:19,113 and then access the log file again, 441 00:23:19,113 --> 00:23:20,717 and we're going to go down to the very bottom 442 00:23:20,717 --> 00:23:23,403 again and see if there's anything new there. 443 00:23:23,403 --> 00:23:26,653 Nothing new, so we're going to then run 444 00:23:29,687 --> 00:23:31,821 the app and see what happens. 445 00:23:31,821 --> 00:23:33,870 So see you in the very next video 446 00:23:33,870 --> 00:23:35,983 and then we're going to look at the logs again 447 00:23:35,983 --> 00:23:39,034 after running a request and see if more 448 00:23:39,034 --> 00:23:41,222 things will be there or not. 449 00:23:41,222 --> 00:23:43,862 If things don't appear, it means that somewhere 450 00:23:43,862 --> 00:23:47,437 our connection between engine.ext, UWSGI, 451 00:23:47,437 --> 00:23:49,801 and our Flask app has gone wrong 452 00:23:49,801 --> 00:23:52,833 and the requests are not reaching the Flask app. 453 00:23:52,833 --> 00:23:56,221 But if things do appear, then hopefully it's not an error, 454 00:23:56,221 --> 00:23:58,584 and then everything should be working. 455 00:23:58,584 --> 00:24:00,709 So without further ado, let's go over 456 00:24:00,709 --> 00:24:04,023 to the next video and we're going to look at that.