WEBVTT 00:00.720 --> 00:01.553 -: In the last section, 00:01.553 --> 00:03.750 we started putting together our container definitions 00:03.750 --> 00:07.350 inside of the Dockerrun.aws.json file. 00:07.350 --> 00:08.280 We're now going to continue 00:08.280 --> 00:10.050 with two other important parameters 00:10.050 --> 00:12.300 that are going to be added to our client container, 00:12.300 --> 00:13.301 right here. 00:13.301 --> 00:15.300 So the next one that we're going to put on 00:15.300 --> 00:17.029 is a flag called essential, 00:17.029 --> 00:20.700 and we're going to set it to false by default. 00:20.700 --> 00:22.890 The essential flag is something that we've not seen before 00:22.890 --> 00:25.200 in any other docker concept. 00:25.200 --> 00:26.760 The essential flag essentially means 00:26.760 --> 00:29.970 that this container right here is not considered to be, 00:29.970 --> 00:32.250 as you might guess, essential. 00:32.250 --> 00:33.982 So what would it mean 00:33.982 --> 00:35.520 if we marked this thing as essential true? 00:35.520 --> 00:38.070 If we marked a container as essential true, 00:38.070 --> 00:41.430 and this container ever crashes for any reason whatsoever, 00:41.430 --> 00:44.070 then all the other containers in this group 00:44.070 --> 00:47.160 of containers will be closed down at the same time. 00:47.160 --> 00:48.060 So in other words, 00:49.036 --> 00:50.820 if we end up with some other containers inside of here, 00:50.820 --> 00:53.250 like let's say container one, 00:53.250 --> 00:55.050 and notice this is not valid syntax, 00:55.050 --> 00:55.950 I just mean to say 00:56.858 --> 00:58.890 that there are some other containers in here. 00:58.890 --> 01:00.960 Now, if client was marked as essential, 01:00.960 --> 01:03.030 and this thing crashed for any reason, 01:03.030 --> 01:04.710 container one and container two 01:04.710 --> 01:06.840 would be automatically shut down as well, 01:06.840 --> 01:09.750 even if they are still running a-okay. 01:09.750 --> 01:11.190 Now, in the case of our client, 01:11.190 --> 01:13.530 if this thing crashes for any reason, 01:13.530 --> 01:14.760 that's kind of okay, 01:14.760 --> 01:16.830 and I would still want all the other containers, 01:16.830 --> 01:17.940 or the other services, 01:17.940 --> 01:20.760 in my group of containers to continue running. 01:20.760 --> 01:23.130 The only service that I have, or we have, 01:23.130 --> 01:25.350 inside this list of container definitions 01:25.350 --> 01:26.970 that you and I really care about 01:26.970 --> 01:29.760 is the NGINX routing server. 01:29.760 --> 01:31.320 Remember, that's the server that routes 01:31.320 --> 01:34.320 to either the client or the API, 01:34.320 --> 01:36.180 the express API that we have. 01:36.180 --> 01:37.590 So if that thing goes down, 01:37.590 --> 01:39.660 it means that no one can access 01:39.660 --> 01:42.870 any of the different services in our group of containers. 01:42.870 --> 01:44.580 And so we're probably gonna want to mark that one 01:44.580 --> 01:46.800 as our essential container to say, 01:46.800 --> 01:48.660 hey, if the engine X server crashes, 01:48.660 --> 01:51.862 well, we can't reach any of the other services 01:51.862 --> 01:52.695 in our grouping of containers, 01:52.695 --> 01:54.360 so we better just shut everything down. 01:55.590 --> 01:57.990 Now, the one little bit of trivia that I wanna share 01:57.990 --> 01:59.670 with you about essential right here 01:59.670 --> 02:03.210 is that at least one service in your listing 02:03.210 --> 02:06.420 of container definitions must be marked as essential. 02:06.420 --> 02:09.540 So at least one thing inside of here has to be essential. 02:09.540 --> 02:10.620 And like I just said, 02:10.620 --> 02:12.540 we're going to treat the NGINX container 02:12.540 --> 02:14.760 as our essential service. 02:14.760 --> 02:17.550 So I'm going to flip the client back over to false 02:17.550 --> 02:19.560 to say that, hey, if this thing crashes, 02:19.560 --> 02:22.470 that's kind of okay, we don't really care. 02:22.470 --> 02:25.170 Now, the last property that we're going to add on here. 02:25.170 --> 02:26.820 Oh actually, you know what I, excuse me, 02:26.820 --> 02:28.830 that was the last one. 02:28.830 --> 02:31.200 Okay, so that's it for our client definition. 02:31.200 --> 02:33.360 We're now going to skip over NGINX 02:33.360 --> 02:35.446 and take care of the server 02:35.446 --> 02:37.440 and the worker container definitions, as well. 02:37.440 --> 02:39.900 Those are both going to end up being very similar 02:39.900 --> 02:42.960 to the client definition that we just put together. 02:42.960 --> 02:44.970 The NGINX one is going to be a little bit different, 02:44.970 --> 02:47.400 that's why we're gonna save it for last. 02:47.400 --> 02:50.040 So after the client definition, I'll put in a comma, 02:50.040 --> 02:52.170 and then open up another record. 02:52.170 --> 02:54.270 Remember, every one of these objects right here 02:54.270 --> 02:57.183 represents a different container that we want to create. 02:58.200 --> 03:00.803 So the next one is going to have a name, 03:00.803 --> 03:02.520 and we'll do the server. 03:02.520 --> 03:04.683 So I'll call this server. 03:05.880 --> 03:10.880 The image that we're going to use is multi-server. 03:12.210 --> 03:16.920 So we'll say your Docker ID/multi-server, 03:16.920 --> 03:18.690 and then the host name this time around, 03:18.690 --> 03:21.908 remember that when we put together our host name 03:21.908 --> 03:24.360 inside of the NGINX default.com file right here, 03:24.360 --> 03:25.290 if you open that file up 03:25.290 --> 03:28.718 you'll recall that we actually renamed that endpoint 03:28.718 --> 03:30.150 or that host name to be API, 03:30.150 --> 03:33.120 because we have been calling that Express Project Server. 03:33.120 --> 03:34.890 But we very quickly realized that, 03:34.890 --> 03:36.390 you know, if we called everything server, 03:36.390 --> 03:38.760 stuff was gonna get really confusing, really quickly, 03:38.760 --> 03:40.290 and it just didn't make a lot of sense. 03:40.290 --> 03:44.673 And so we ended up renaming this host as API instead. 03:45.570 --> 03:46.860 So for the host name over here, 03:46.860 --> 03:48.180 rather than making use of server, 03:48.180 --> 03:49.680 we're going to use API, 03:49.680 --> 03:52.590 because that is what the NGINX is going to look for 03:52.590 --> 03:55.173 when it tries to redirect traffic upstream. 03:56.700 --> 03:59.790 And then finally, we'll add on an essential to this one 03:59.790 --> 04:01.710 and this will also be false because, 04:01.710 --> 04:04.260 yeah, it's not the best thing if our server crashes 04:04.260 --> 04:06.540 for any given reason, but if it does crash, 04:06.540 --> 04:08.460 well, there's not a good reason to shut down 04:08.460 --> 04:10.023 everything else as well. 04:12.000 --> 04:14.250 Okay, so now onto the next one, 04:14.250 --> 04:17.040 we'll move on to our worker container. 04:17.040 --> 04:19.920 So I'll do a name of worker, 04:19.920 --> 04:24.287 we'll do an image of your Docker ID/multi-worker. 04:26.490 --> 04:29.700 Our host name is going to be Worker, 04:29.700 --> 04:31.830 and essential, as you might guess, yep, 04:31.830 --> 04:33.390 this one's also false. 04:33.390 --> 04:36.300 So out of all the services that we have, without a doubt, 04:36.300 --> 04:39.690 the worker crashing is the least of our concerns. 04:39.690 --> 04:41.070 If the worker crashes, 04:41.070 --> 04:44.250 our application can still be visited by users. 04:44.250 --> 04:47.010 Users can still enter in indices to be calculated, 04:47.010 --> 04:49.620 and they can still see values that have already 04:49.620 --> 04:52.380 been calculated by the worker in the past. 04:52.380 --> 04:53.670 So if the worker crashes, 04:53.670 --> 04:55.860 that just means that we're not going to calculate any values 04:55.860 --> 04:57.990 in the future, and I'm totally okay with that. 04:57.990 --> 05:00.270 If that happens, no big deal. 05:00.270 --> 05:01.770 We could definitely do a little bit of debugging, 05:01.770 --> 05:03.090 figure out why the worker crash, 05:03.090 --> 05:04.770 and then figure out some way to start it back up 05:04.770 --> 05:06.180 in the future. 05:06.180 --> 05:08.250 Okay, so that's it for container definitions 05:08.250 --> 05:10.080 for the client server and worker. 05:10.080 --> 05:12.300 Now we have to do the NGINX one last here, 05:12.300 --> 05:13.470 so let's take another quick pause. 05:13.470 --> 05:14.850 We'll come back in the next section 05:14.850 --> 05:17.574 and we'll take care of that container definition. 05:17.574 --> 05:18.683 So I'll see you in just a minute.