WEBVTT 00:00.570 --> 00:02.640 -: In the last section, we learned how to temporarily 00:02.640 --> 00:05.310 reconfigure a single terminal window 00:05.310 --> 00:07.050 to access our Docker server 00:07.050 --> 00:09.060 running inside the virtual machine. 00:09.060 --> 00:10.590 I want to remind you again, 00:10.590 --> 00:12.960 you have to rerun that command every single time 00:12.960 --> 00:14.910 that you open up a new terminal window. 00:15.750 --> 00:17.910 All right, so I'm gonna very quickly paste this 00:17.910 --> 00:19.800 inside of here just to make sure it's really clear 00:19.800 --> 00:21.060 that I'm going to reconfigure 00:21.060 --> 00:22.950 my current terminal window right here. 00:22.950 --> 00:24.450 Now I wanna talk to you a little bit about 00:24.450 --> 00:26.190 why we would want to do this at all. 00:26.190 --> 00:28.051 Why would we want to reach into the virtual machine 00:28.051 --> 00:30.750 and take a look at the Docker server 00:30.750 --> 00:33.240 and all the containers that are running inside there? 00:33.240 --> 00:35.473 Well, I put together a couple of reasons that I think 00:35.473 --> 00:36.780 you might want to do this, 00:36.780 --> 00:39.630 this is not an exhaustive list by any means. 00:39.630 --> 00:41.730 So I just want you to have an additional tool 00:41.730 --> 00:44.130 in your little toolkit for working with Kubernetes 00:44.130 --> 00:46.920 so that you can understand how to kind of get a better idea 00:46.920 --> 00:49.290 of how to play around with all this stuff. 00:49.290 --> 00:50.880 All right, so a couple of reasons that you might want to 00:50.880 --> 00:53.460 mess around with Docker inside of our node. 00:53.460 --> 00:55.320 The first reason is that you can use 00:55.320 --> 00:57.060 all the same debugging techniques 00:57.060 --> 00:58.950 that we had learned much earlier in this course 00:58.950 --> 01:01.823 to inspect containers and get logs from them 01:01.823 --> 01:04.230 and do all that kind of stuff 01:04.230 --> 01:05.940 when you connect to the copy of Docker 01:05.940 --> 01:07.470 running inside the node. 01:07.470 --> 01:10.530 So for example, remember right here again 01:10.530 --> 01:12.210 I just reconfigured my shell 01:12.210 --> 01:14.190 so I'm gonna do a docker ps, 01:14.190 --> 01:17.190 and when I do so I can scroll all the way back up to the top 01:17.190 --> 01:21.240 and get the ID of my multi-client container right here. 01:21.240 --> 01:23.430 So I'm gonna copy that ID. 01:23.430 --> 01:25.320 Now, I can get logs outta that container 01:25.320 --> 01:28.080 by doing a very classic docker logs, 01:28.080 --> 01:29.850 and then the ID of the container. 01:29.850 --> 01:32.250 Remember, this is something we covered way long ago 01:32.250 --> 01:34.110 at the very start of the course. 01:34.110 --> 01:36.930 Now in this case, our container has not emitted any logs, 01:36.930 --> 01:38.760 so I get nothing back here 01:38.760 --> 01:40.380 but I could do other commands as well, 01:40.380 --> 01:43.040 such as, say, executing an arbitrary program, 01:43.040 --> 01:45.630 or a secondary program inside the container. 01:45.630 --> 01:47.850 So for example, if I want to start up a shell 01:47.850 --> 01:49.230 inside of that container, 01:49.230 --> 01:54.230 I could do a docker exec -it, then the container id, 01:54.300 --> 01:56.790 and then I'll start up shell inside there. 01:56.790 --> 01:59.670 And so when I do that, I can very simply get a shell 01:59.670 --> 02:02.160 and I can start to poke around and get a better idea 02:02.160 --> 02:04.323 of the state of my container if I want to. 02:05.310 --> 02:07.080 Now, the one kind of caveat to this, 02:07.080 --> 02:08.790 the one thing I want to mention, 02:08.790 --> 02:11.310 is that a lot of these different debugging commands 02:11.310 --> 02:14.640 are actually available through kubectl as well. 02:14.640 --> 02:18.420 So for example, I can still pull logs using kubectl 02:18.420 --> 02:20.280 from a very specific container, 02:20.280 --> 02:22.950 and I can start up a shell and slide of a specific container 02:22.950 --> 02:24.720 using kubectl as well. 02:24.720 --> 02:26.433 As a very quick example of that, 02:27.540 --> 02:29.910 I'll do a kubectl get pods. 02:29.910 --> 02:32.610 I'm gonna copy the name of my pod right here, 02:32.610 --> 02:35.460 and then I'll do a kubectl logs, 02:35.460 --> 02:38.250 and I'll paste the name of the pod. 02:38.250 --> 02:39.570 And again, I don't get anything back 02:39.570 --> 02:41.760 because the container has not emitted any logs 02:41.760 --> 02:43.710 but it definitely would retrieve logs 02:43.710 --> 02:45.840 if any had been emitted. 02:45.840 --> 02:49.920 I can also do a kubectl exec -it, 02:49.920 --> 02:51.330 and then the pod name, 02:51.330 --> 02:54.240 and then -sh on the very end to start up a shell. 02:54.240 --> 02:55.500 And so the same thing right here, 02:55.500 --> 02:59.010 yeah, I'm starting at a shell using kubectl as well. 02:59.010 --> 03:01.110 So again, you can use all the knowledge 03:01.110 --> 03:04.020 that you have of Docker to do a lot of debugging. 03:04.020 --> 03:06.090 However, a lot of that stuff is already available 03:06.090 --> 03:07.050 with kubectl. 03:07.050 --> 03:08.400 So I'm gonna kind of leave it up to you 03:08.400 --> 03:10.560 if you want to figure out how to do this stuff 03:10.560 --> 03:11.850 through kubectl, 03:11.850 --> 03:13.443 or if you want you to stick with your knowledge 03:13.443 --> 03:15.690 that you've already gained of Docker, 03:15.690 --> 03:18.210 and use those same techniques as well. 03:18.210 --> 03:20.190 Now, the next reason that we might want to mess around 03:20.190 --> 03:21.690 with Docker inside of our node 03:21.690 --> 03:24.300 is so that we can do exactly what I did a little bit ago 03:24.300 --> 03:25.320 inside the course, 03:25.320 --> 03:27.570 where I manually deleted a container 03:27.570 --> 03:28.980 and then we were able to observe that, 03:28.980 --> 03:31.440 oh, hey it was restarted automatically. 03:31.440 --> 03:33.510 So essentially, you can test Kubernetes' ability 03:33.510 --> 03:36.720 to self-heal or restart crashed containers 03:36.720 --> 03:38.070 or whatever it might be, 03:38.070 --> 03:42.330 by reaching into there and deleting a container manually. 03:42.330 --> 03:44.100 Now, that's not a great reason to do this, 03:44.100 --> 03:45.210 but I just wanna say it's something 03:45.210 --> 03:48.210 that you could possibly do if you felt like it. 03:48.210 --> 03:49.620 Now, the other reason you might do this 03:49.620 --> 03:52.680 is that if you're for some reason having a really tough time 03:52.680 --> 03:54.930 figuring out why images are being cached 03:54.930 --> 03:57.570 inside of your node, talking about Docker images here, 03:57.570 --> 03:59.100 and if for some reason it feels like 03:59.100 --> 04:01.290 you're not able to update the image 04:01.290 --> 04:04.620 that a particular container is using, 04:04.620 --> 04:07.230 you can always reach into the container, 04:07.230 --> 04:09.060 access the copy of Docker inside there, 04:09.060 --> 04:11.160 and say, hey, delete your image cache 04:11.160 --> 04:14.760 and just blow away all the cached images that you have. 04:14.760 --> 04:17.040 And so to do that, we could run the same command 04:17.040 --> 04:18.963 that we had learned way long ago. 04:19.800 --> 04:22.980 We can do a Docker system prune -a 04:22.980 --> 04:25.650 and this will remove all stopped containers, 04:25.650 --> 04:28.530 all unused networks, and all build cache, 04:28.530 --> 04:31.110 and all images that are not being used at this point. 04:31.110 --> 04:33.270 So I could just blow away everything inside there 04:33.270 --> 04:37.110 if for some reason I felt like there was a big caching issue 04:37.110 --> 04:39.333 with what was going on inside of my node. 04:40.410 --> 04:41.940 Okay, so that's it, that's a couple of reasons 04:41.940 --> 04:43.650 on why you would want to mess around with Docker 04:43.650 --> 04:44.483 in the node. 04:44.483 --> 04:47.220 Now, I just give these to you as like possibilities. 04:47.220 --> 04:49.440 Again, I'm rather convinced that you can think of 04:49.440 --> 04:51.810 some better reasons than what I've listed here 04:51.810 --> 04:53.580 of messing around with Docker inside the node. 04:53.580 --> 04:56.280 But again, I just wanted to give you a couple examples 04:56.280 --> 04:58.050 to kind of get your brain going 04:58.050 --> 05:00.780 and give you a reason to look into this feature 05:00.780 --> 05:02.010 a little bit more. 05:02.010 --> 05:03.300 All right, so let's take a pause right here, 05:03.300 --> 05:05.250 and we'll continue in the next section.