1 00:00:00,120 --> 00:00:01,830 In this lesson, we're going to dive, 2 00:00:01,830 --> 00:00:03,960 into the world of virtualization technologies, 3 00:00:03,960 --> 00:00:06,360 because the cloud relies on virtualization 4 00:00:06,360 --> 00:00:08,280 to allow end-users to run virtual machines 5 00:00:08,280 --> 00:00:10,410 on these cloud-based servers. 6 00:00:10,410 --> 00:00:13,320 This, in turn, allows multiple organizations and customers 7 00:00:13,320 --> 00:00:15,060 to share one physical server 8 00:00:15,060 --> 00:00:17,070 while keeping their own virtualized servers safe 9 00:00:17,070 --> 00:00:19,560 and isolated from the other organizations located 10 00:00:19,560 --> 00:00:21,720 on that same physical server. 11 00:00:21,720 --> 00:00:25,050 Virtualization enables a much more efficient use of hardware 12 00:00:25,050 --> 00:00:26,760 and it can provide us with fault tolerance, 13 00:00:26,760 --> 00:00:29,250 disaster recovery, and scalability. 14 00:00:29,250 --> 00:00:31,770 This also is one of the main reasons why virtualization 15 00:00:31,770 --> 00:00:34,530 has become the foundation of cloud computing. 16 00:00:34,530 --> 00:00:36,870 Cloud providers virtualize all the resources 17 00:00:36,870 --> 00:00:38,880 that they want to make available to their customers 18 00:00:38,880 --> 00:00:42,060 in order to easily manage all of those given resources. 19 00:00:42,060 --> 00:00:44,520 This occurs in every model of cloud computing, 20 00:00:44,520 --> 00:00:47,310 including SaaS, PaaS, and IaaS. 21 00:00:47,310 --> 00:00:50,370 By using virtualization, an administrator can easily build 22 00:00:50,370 --> 00:00:53,130 and then later tear down an entire cluster of systems 23 00:00:53,130 --> 00:00:54,510 with a single action. 24 00:00:54,510 --> 00:00:57,270 Or they can completely automate this process 25 00:00:57,270 --> 00:00:59,880 in response to changes in the environmental conditions, 26 00:00:59,880 --> 00:01:01,590 so that new servers will come online 27 00:01:01,590 --> 00:01:03,150 during periods of high demand, 28 00:01:03,150 --> 00:01:05,850 and those same servers can be remove or shut down 29 00:01:05,850 --> 00:01:07,860 during periods of low demand. 30 00:01:07,860 --> 00:01:09,780 To run virtual machines on a server, 31 00:01:09,780 --> 00:01:12,900 the physical server must have a hypervisor installed. 32 00:01:12,900 --> 00:01:14,640 The hypervisor is a software layer 33 00:01:14,640 --> 00:01:16,860 that provides control between virtual machines 34 00:01:16,860 --> 00:01:18,480 and the physical hardware. 35 00:01:18,480 --> 00:01:20,760 It's going to manage the allocation of hardware, 36 00:01:20,760 --> 00:01:22,530 control all the networking functions 37 00:01:22,530 --> 00:01:25,500 and conduct all the administrative control of the systems. 38 00:01:25,500 --> 00:01:27,090 There are two types of hypervisors 39 00:01:27,090 --> 00:01:28,650 you're going to find out in the field, 40 00:01:28,650 --> 00:01:30,660 type one and type two. 41 00:01:30,660 --> 00:01:33,870 Type one hypervisors are going to run directly on the hardware 42 00:01:33,870 --> 00:01:36,180 in what is known as a bare metal configuration 43 00:01:36,180 --> 00:01:37,380 or deployment. 44 00:01:37,380 --> 00:01:40,530 Type one hypervisors tend to be more resource efficient, 45 00:01:40,530 --> 00:01:42,600 because they don't run an entire operating system 46 00:01:42,600 --> 00:01:46,170 like Linux, Windows, or OS X in order to operate. 47 00:01:46,170 --> 00:01:48,540 And so this frees up more physical resources 48 00:01:48,540 --> 00:01:50,550 such as processing power and memory 49 00:01:50,550 --> 00:01:53,790 to the virtual machines it host on that physical server. 50 00:01:53,790 --> 00:01:58,350 Some good examples of type one hypervisors are VMware's ESXi 51 00:01:58,350 --> 00:02:01,110 and Microsoft's Hyper-V implementations. 52 00:02:01,110 --> 00:02:03,930 Type two hypervisors are going to be run as a service 53 00:02:03,930 --> 00:02:06,330 on top of a locally installed operating system 54 00:02:06,330 --> 00:02:09,210 such as Linux, Windows, or OS X. 55 00:02:09,210 --> 00:02:12,360 These hypervisors require additional resources to operate 56 00:02:12,360 --> 00:02:15,150 because they first have to load up the full operating system 57 00:02:15,150 --> 00:02:16,680 and then the full hypervisor 58 00:02:16,680 --> 00:02:18,840 and then the guest virtual machine 59 00:02:18,840 --> 00:02:20,130 with its operating systems 60 00:02:20,130 --> 00:02:22,140 in order for everything to operate. 61 00:02:22,140 --> 00:02:25,920 Oracle's VirtualBox, VMware Fusion and QEMU 62 00:02:25,920 --> 00:02:29,370 are examples of commonly used type two hypervisors. 63 00:02:29,370 --> 00:02:30,690 Now, on Linux systems, 64 00:02:30,690 --> 00:02:34,423 you'll also find KVM or kernel based virtual machines. 65 00:02:34,423 --> 00:02:37,140 A KVM or kernel based virtual machine 66 00:02:37,140 --> 00:02:39,570 is a Linux based virtualization solution 67 00:02:39,570 --> 00:02:42,030 that can be added to most Linux distributions. 68 00:02:42,030 --> 00:02:43,980 It's going to enable the management of virtual machines 69 00:02:43,980 --> 00:02:46,950 on Linux platforms with attributes of both the type one 70 00:02:46,950 --> 00:02:49,050 and a type two hypervisor. 71 00:02:49,050 --> 00:02:51,330 KVM is really a fairly efficient way 72 00:02:51,330 --> 00:02:52,440 to host virtual machines 73 00:02:52,440 --> 00:02:54,030 if you're already running a Linux server 74 00:02:54,030 --> 00:02:57,180 as the operating system for that physical server. 75 00:02:57,180 --> 00:02:58,950 Now, when you're working with virtual machines, 76 00:02:58,950 --> 00:03:01,620 it's important to create and use virtual machine templates 77 00:03:01,620 --> 00:03:04,320 to make your deployments easier and more efficient. 78 00:03:04,320 --> 00:03:06,000 By using predefined templates, 79 00:03:06,000 --> 00:03:07,920 you can allow your administrators and end-users 80 00:03:07,920 --> 00:03:10,890 to deploy servers themselves in a self-service environment 81 00:03:10,890 --> 00:03:12,750 using those predefined templates 82 00:03:12,750 --> 00:03:15,300 by specifying different processors, memory, 83 00:03:15,300 --> 00:03:17,160 storage, and network configurations 84 00:03:17,160 --> 00:03:19,230 for the virtual machines that are going to be created 85 00:03:19,230 --> 00:03:21,120 and launched by those templates. 86 00:03:21,120 --> 00:03:23,040 There are different template files and formats 87 00:03:23,040 --> 00:03:24,630 that you might come across in the field 88 00:03:24,630 --> 00:03:26,220 as a system administrator. 89 00:03:26,220 --> 00:03:31,220 This includes OVF, JSON, YAML, and container images. 90 00:03:31,740 --> 00:03:35,460 Now, the open virtualization format or OVF is a format 91 00:03:35,460 --> 00:03:38,610 that contains the necessary configuration files, packages, 92 00:03:38,610 --> 00:03:41,790 and settings for virtual machines and network devices. 93 00:03:41,790 --> 00:03:43,680 These files may be used in the deployment 94 00:03:43,680 --> 00:03:46,350 of virtual machines in a virtualized cloud environment 95 00:03:46,350 --> 00:03:48,990 using automation and orchestration. 96 00:03:48,990 --> 00:03:53,880 JSON or JSON is the JavaScript object notation format, 97 00:03:53,880 --> 00:03:55,740 and it's used by most programming languages 98 00:03:55,740 --> 00:03:57,240 to store information. 99 00:03:57,240 --> 00:03:59,520 This makes JSON really easy to interpret 100 00:03:59,520 --> 00:04:02,430 and use inside of your automations and orchestrations 101 00:04:02,430 --> 00:04:05,280 whenever you're interacting with it programmatically. 102 00:04:05,280 --> 00:04:10,280 The next one we have is YAML, or YAML aint markup language. 103 00:04:10,380 --> 00:04:12,000 Now, the YAML format is used 104 00:04:12,000 --> 00:04:13,680 to store configuration information 105 00:04:13,680 --> 00:04:16,019 on newly deployed virtual machines. 106 00:04:16,019 --> 00:04:19,440 YAML is commonly used by cloud service providers like AWS 107 00:04:19,440 --> 00:04:21,630 to install software or create user accounts 108 00:04:21,630 --> 00:04:23,700 during a virtual machine's first boot, 109 00:04:23,700 --> 00:04:26,190 or by orchestration tools like Ansible 110 00:04:26,190 --> 00:04:28,620 during the deployment of virtual machines. 111 00:04:28,620 --> 00:04:29,700 The fourth type we have 112 00:04:29,700 --> 00:04:32,280 is known as a container image template file. 113 00:04:32,280 --> 00:04:33,510 And these are another format 114 00:04:33,510 --> 00:04:35,880 that's used by specialized types of virtual machines 115 00:04:35,880 --> 00:04:37,470 known as containers. 116 00:04:37,470 --> 00:04:39,660 These container files contain everything needed 117 00:04:39,660 --> 00:04:40,830 for that container, 118 00:04:40,830 --> 00:04:44,190 including the applications and supporting configurations. 119 00:04:44,190 --> 00:04:46,740 Now, let's talk for a minute about the boot process 120 00:04:46,740 --> 00:04:48,270 and bootstrapping. 121 00:04:48,270 --> 00:04:50,820 Bootstrapping refers to the adage of pulling yourself up 122 00:04:50,820 --> 00:04:51,960 by the bootstraps, 123 00:04:51,960 --> 00:04:53,820 which means that the operating system starts 124 00:04:53,820 --> 00:04:55,890 with simple layers and then moves upwards 125 00:04:55,890 --> 00:04:57,810 towards more complex functionality 126 00:04:57,810 --> 00:04:59,940 as the boot process progresses. 127 00:04:59,940 --> 00:05:02,640 With virtual machines, the bootstrapping steps are handled 128 00:05:02,640 --> 00:05:04,200 by the virtualization layer, 129 00:05:04,200 --> 00:05:06,240 and it's possible to modify the startup 130 00:05:06,240 --> 00:05:07,680 and the deployment of virtual machines 131 00:05:07,680 --> 00:05:09,780 during the bootstrapping sequences. 132 00:05:09,780 --> 00:05:12,090 There are three ways of managing bootstrapping, 133 00:05:12,090 --> 00:05:15,570 including Cloud-init, Anaconda and Kickstart. 134 00:05:15,570 --> 00:05:18,210 Cloud-init is a cloud-based Linux mechanism 135 00:05:18,210 --> 00:05:21,270 to customize a virtual machine during its first boot up. 136 00:05:21,270 --> 00:05:23,910 This customization might include security settings, 137 00:05:23,910 --> 00:05:26,820 software package installations, user and group creation 138 00:05:26,820 --> 00:05:28,290 and much more. 139 00:05:28,290 --> 00:05:31,770 Anaconda is another method used by many Linux distributions 140 00:05:31,770 --> 00:05:33,360 to manage their deployments. 141 00:05:33,360 --> 00:05:35,340 The Anaconda installer can provide prompts 142 00:05:35,340 --> 00:05:38,160 to an administrator to configure the new Linux server, 143 00:05:38,160 --> 00:05:40,860 or it can reference template files to customize 144 00:05:40,860 --> 00:05:43,950 the installation automatically using automation. 145 00:05:43,950 --> 00:05:46,080 The third type is known as Kickstart. 146 00:05:46,080 --> 00:05:48,540 Now, Kickstart is another method used by Linux 147 00:05:48,540 --> 00:05:51,270 to customize the installation and provide an automated 148 00:05:51,270 --> 00:05:54,300 and unattended installation of new virtual machines. 149 00:05:54,300 --> 00:05:56,970 The Kickstart file is going to provide all the information 150 00:05:56,970 --> 00:05:59,910 about partitions, packages, user accounts, 151 00:05:59,910 --> 00:06:01,650 software deployments and more 152 00:06:01,650 --> 00:06:03,600 that's going to be needed to install, set up 153 00:06:03,600 --> 00:06:06,570 and configure those new virtual machines. 154 00:06:06,570 --> 00:06:09,030 Another area we need to cover in terms of virtual machines 155 00:06:09,030 --> 00:06:12,210 is storage, because all these virtual machines need a method 156 00:06:12,210 --> 00:06:14,490 to store and process their data. 157 00:06:14,490 --> 00:06:16,230 With traditional physical computers, 158 00:06:16,230 --> 00:06:18,540 storage capacity is provided as physical space 159 00:06:18,540 --> 00:06:19,830 on a given hard disk 160 00:06:19,830 --> 00:06:23,010 or partition locate on one or more storage drives. 161 00:06:23,010 --> 00:06:24,450 With virtualization though, 162 00:06:24,450 --> 00:06:27,180 storage capacity itself can also be virtualized 163 00:06:27,180 --> 00:06:30,630 across a large RAID device or storage area networks. 164 00:06:30,630 --> 00:06:33,270 And then smaller portions of that larger storage 165 00:06:33,270 --> 00:06:34,890 can be presented to the virtual machines 166 00:06:34,890 --> 00:06:38,460 as virtual storage devices or virtual storage drives. 167 00:06:38,460 --> 00:06:40,740 The virtual storage drive is simply a file 168 00:06:40,740 --> 00:06:42,420 that resides on the physical drive 169 00:06:42,420 --> 00:06:45,690 like any other data file on that underlying hard drive, 170 00:06:45,690 --> 00:06:48,630 but the virtual machine treats that single file 171 00:06:48,630 --> 00:06:51,060 as if it was an entire physical drive. 172 00:06:51,060 --> 00:06:53,580 It's going to be partitioned and given a file system, 173 00:06:53,580 --> 00:06:55,080 a boot loader is going to be installed, 174 00:06:55,080 --> 00:06:57,660 and an operating system is going to be deployed all inside 175 00:06:57,660 --> 00:07:00,720 this virtual container of this data file. 176 00:07:00,720 --> 00:07:02,430 While the virtual drive is just a file 177 00:07:02,430 --> 00:07:04,710 from our perspective as system administrators, 178 00:07:04,710 --> 00:07:06,480 the virtual machine truly believes 179 00:07:06,480 --> 00:07:08,220 that this is a real physical device 180 00:07:08,220 --> 00:07:10,650 just like any other hard disk drive. 181 00:07:10,650 --> 00:07:12,480 Now, when you're deploying virtual machines, 182 00:07:12,480 --> 00:07:15,300 you may be offered the option of configuring thin storage 183 00:07:15,300 --> 00:07:16,830 or thick storage. 184 00:07:16,830 --> 00:07:19,530 Thin storage refers to a virtual storage device file 185 00:07:19,530 --> 00:07:23,070 that's going to grow on demand up to a maximum file size. 186 00:07:23,070 --> 00:07:25,770 This tends to be a more efficient use of your drive space, 187 00:07:25,770 --> 00:07:28,920 but it does have the drawback of having slower performance 188 00:07:28,920 --> 00:07:30,870 than a thick storage system. 189 00:07:30,870 --> 00:07:32,730 Thin provisioning is most appropriate 190 00:07:32,730 --> 00:07:34,140 in environments where the cost 191 00:07:34,140 --> 00:07:37,350 of maintaining large storage pools is much more of a concern 192 00:07:37,350 --> 00:07:40,020 than the risk of temporarily running out of storage. 193 00:07:40,020 --> 00:07:42,210 For example, if you're running virtual box 194 00:07:42,210 --> 00:07:43,890 on your workstation to install Linux 195 00:07:43,890 --> 00:07:46,920 as your virtual machine, you can choose thin provisioning 196 00:07:46,920 --> 00:07:48,540 since we don't really want to use up a ton 197 00:07:48,540 --> 00:07:49,770 of your hard drive space 198 00:07:49,770 --> 00:07:52,410 when we initially create a virtual machine. 199 00:07:52,410 --> 00:07:54,120 Thick provisioning on the other hand 200 00:07:54,120 --> 00:07:56,400 is going to immediately reserve the allocated space 201 00:07:56,400 --> 00:07:58,170 for use by the virtual device, 202 00:07:58,170 --> 00:08:00,480 regardless of whether or not that much capacity 203 00:08:00,480 --> 00:08:02,040 is actually needed. 204 00:08:02,040 --> 00:08:04,260 So if you've installed a virtual machine 205 00:08:04,260 --> 00:08:05,700 and set up the virtual drive 206 00:08:05,700 --> 00:08:08,010 to have a one terabyte volume size, 207 00:08:08,010 --> 00:08:11,190 it's actually going to create a one terabyte file immediately 208 00:08:11,190 --> 00:08:13,050 during the virtual machine creation, 209 00:08:13,050 --> 00:08:15,330 if you choose to use this thick provisioning. 210 00:08:15,330 --> 00:08:17,400 Now, even if the initial Linux operating system 211 00:08:17,400 --> 00:08:19,350 you're installing in that virtual machine 212 00:08:19,350 --> 00:08:21,480 only needs eight gigabytes to install, 213 00:08:21,480 --> 00:08:22,560 it's still going to go ahead 214 00:08:22,560 --> 00:08:25,770 and reserve the entire one terabytes of file space. 215 00:08:25,770 --> 00:08:27,600 Now, the benefit of thick provisioning 216 00:08:27,600 --> 00:08:28,920 is that the performance is better 217 00:08:28,920 --> 00:08:30,750 and that you're guaranteed to have the space available 218 00:08:30,750 --> 00:08:31,920 whenever you need it. 219 00:08:31,920 --> 00:08:33,270 But its drawback 220 00:08:33,270 --> 00:08:36,419 is that you instantly used up a ton of physical disk space 221 00:08:36,419 --> 00:08:38,429 even if you really didn't need it all. 222 00:08:38,429 --> 00:08:41,010 Thick provisioning is most appropriate in the environments 223 00:08:41,010 --> 00:08:43,470 where disruptions to the continuous storage process 224 00:08:43,470 --> 00:08:45,810 presents a larger risk and you're less concerned 225 00:08:45,810 --> 00:08:47,370 with increasing your storage costs 226 00:08:47,370 --> 00:08:49,980 than you are with mitigating that risk. 227 00:08:49,980 --> 00:08:52,380 Data can also be stored in multiple different ways 228 00:08:52,380 --> 00:08:54,300 when you're interacting in the cloud. 229 00:08:54,300 --> 00:08:57,240 One of these is to use a traditional SQL database 230 00:08:57,240 --> 00:08:59,820 like MariaDB or MySQL. 231 00:08:59,820 --> 00:09:02,910 It's also possible to store data in an unstructured manner, 232 00:09:02,910 --> 00:09:04,830 which is referred to as a blob, 233 00:09:04,830 --> 00:09:06,480 as Microsoft Azure likes to call it, 234 00:09:06,480 --> 00:09:09,540 or a bucket, as AWS likes to call it. 235 00:09:09,540 --> 00:09:12,540 Now, a blob really stands for binary large object, 236 00:09:12,540 --> 00:09:14,160 and it really is the same thing we're talking 237 00:09:14,160 --> 00:09:15,180 about with buckets, 238 00:09:15,180 --> 00:09:17,670 which is just an example of object storage. 239 00:09:17,670 --> 00:09:21,060 If you hear blob or bucket, they mean the exact same thing. 240 00:09:21,060 --> 00:09:22,020 The only difference 241 00:09:22,020 --> 00:09:24,210 is which cloud provider you're referring to. 242 00:09:24,210 --> 00:09:25,860 Blobs are used by Azure. 243 00:09:25,860 --> 00:09:27,960 Buckets are used by AWS. 244 00:09:27,960 --> 00:09:30,330 Blobs and buckets can be used to store audio, 245 00:09:30,330 --> 00:09:33,270 video, multimedia, and text files. 246 00:09:33,270 --> 00:09:35,730 Now, the data that's actually written to the storage device, 247 00:09:35,730 --> 00:09:38,040 whether it's physical or a virtual device, 248 00:09:38,040 --> 00:09:40,050 are actually going to be put there in small chunks. 249 00:09:40,050 --> 00:09:41,970 And we call these blocks. 250 00:09:41,970 --> 00:09:44,340 These blocks are the fundamental storage areas 251 00:09:44,340 --> 00:09:45,690 of your hard drive. 252 00:09:45,690 --> 00:09:47,430 Now, most files are going to be too large 253 00:09:47,430 --> 00:09:49,260 should be stored in a single block. 254 00:09:49,260 --> 00:09:50,730 So the broken down into pieces 255 00:09:50,730 --> 00:09:52,980 that are then written into these blocks. 256 00:09:52,980 --> 00:09:55,080 Later on when you want to read that file, 257 00:09:55,080 --> 00:09:56,670 the hard drive or storage device 258 00:09:56,670 --> 00:09:58,680 is going to grab all those different blocks, 259 00:09:58,680 --> 00:10:00,660 reassemble them into the complete file 260 00:10:00,660 --> 00:10:03,120 and present that to you as a user. 261 00:10:03,120 --> 00:10:06,660 All right, let's talk about networking and virtualization. 262 00:10:06,660 --> 00:10:09,060 The virtualization hypervisor can be configured 263 00:10:09,060 --> 00:10:11,070 to provide access to networking services 264 00:10:11,070 --> 00:10:12,810 in several different ways. 265 00:10:12,810 --> 00:10:14,250 The virtual machine can be configured 266 00:10:14,250 --> 00:10:17,880 with one or more virtual NICs or network interface cards. 267 00:10:17,880 --> 00:10:19,650 These virtual NICs can then be connected 268 00:10:19,650 --> 00:10:22,710 to virtual switches within that hypervisor as well. 269 00:10:22,710 --> 00:10:25,080 Those virtual switches can then be given access 270 00:10:25,080 --> 00:10:27,990 to the host computers physical network interface card 271 00:10:27,990 --> 00:10:30,030 and there's some different configuration options 272 00:10:30,030 --> 00:10:31,080 that you can use. 273 00:10:31,080 --> 00:10:32,790 Things like no networking. 274 00:10:32,790 --> 00:10:34,950 This is an option that simulates a computer 275 00:10:34,950 --> 00:10:36,930 that does not have a NIC cart at all, 276 00:10:36,930 --> 00:10:38,970 and therefore, there's no network connectivity 277 00:10:38,970 --> 00:10:40,680 for that virtual machine. 278 00:10:40,680 --> 00:10:43,500 The internal option is where the VM is going to be connected 279 00:10:43,500 --> 00:10:46,200 to a virtual switch that permits network communication 280 00:10:46,200 --> 00:10:48,090 with other virtual machines connected 281 00:10:48,090 --> 00:10:50,010 to that same virtual switch. 282 00:10:50,010 --> 00:10:52,020 This will not allow them to have network communication 283 00:10:52,020 --> 00:10:53,460 with the host operating system 284 00:10:53,460 --> 00:10:55,890 or the physical network interface card, 285 00:10:55,890 --> 00:10:57,840 only other virtual machines connected 286 00:10:57,840 --> 00:10:59,490 to that virtual switch. 287 00:10:59,490 --> 00:11:01,740 The private option allows the virtual machine 288 00:11:01,740 --> 00:11:03,570 to be connected to a virtual switch 289 00:11:03,570 --> 00:11:04,860 that permits network communication 290 00:11:04,860 --> 00:11:06,450 with other virtual machines 291 00:11:06,450 --> 00:11:08,850 and the host operating system too. 292 00:11:08,850 --> 00:11:10,800 But there is no network connectivity 293 00:11:10,800 --> 00:11:12,210 out to the physical NIC, 294 00:11:12,210 --> 00:11:14,730 and therefore, not to the public internet. 295 00:11:14,730 --> 00:11:16,800 Finally, we have the public option. 296 00:11:16,800 --> 00:11:19,140 The public option is where the virtual machine is connected 297 00:11:19,140 --> 00:11:21,600 to a virtual switch that permits network communication 298 00:11:21,600 --> 00:11:23,010 with other virtual machines, 299 00:11:23,010 --> 00:11:26,190 the host operating system and the physical NIC. 300 00:11:26,190 --> 00:11:28,530 This configuration will expose the virtual machine 301 00:11:28,530 --> 00:11:30,810 to the business network and to the internet 302 00:11:30,810 --> 00:11:31,800 where it can then participate 303 00:11:31,800 --> 00:11:34,890 as if it was a regular physical client or server. 304 00:11:34,890 --> 00:11:36,750 Now, networking and virtual environments 305 00:11:36,750 --> 00:11:39,750 is as flexible as it is in physical environments. 306 00:11:39,750 --> 00:11:42,720 Services like network address translation, or NAT, 307 00:11:42,720 --> 00:11:45,480 can still provide the same functionality in virtual networks 308 00:11:45,480 --> 00:11:47,370 as they do in physical networks. 309 00:11:47,370 --> 00:11:49,680 When you use NTA, it's going to be used to translate 310 00:11:49,680 --> 00:11:52,200 between the reserved private IP address ranges 311 00:11:52,200 --> 00:11:55,680 and the public internet accessible IP address ranges. 312 00:11:55,680 --> 00:11:57,810 These virtualized networks can also be thought of 313 00:11:57,810 --> 00:12:01,050 as overlay networks, especially when they're deployed inside 314 00:12:01,050 --> 00:12:02,430 of a cloud environment. 315 00:12:02,430 --> 00:12:04,470 The term overlay network simply means 316 00:12:04,470 --> 00:12:07,320 that one network is built on top of another. 317 00:12:07,320 --> 00:12:10,050 Virtualized network environments also support bridging, 318 00:12:10,050 --> 00:12:11,490 which connects two networks together 319 00:12:11,490 --> 00:12:13,260 into a single managed unit, 320 00:12:13,260 --> 00:12:14,910 whether those are two virtual networks 321 00:12:14,910 --> 00:12:17,310 or a virtual and physical network. 322 00:12:17,310 --> 00:12:20,190 Now, most virtual host servers are going to run Linux 323 00:12:20,190 --> 00:12:22,200 without a graphical user interface 324 00:12:22,200 --> 00:12:25,230 in order to save on memory and processing resources. 325 00:12:25,230 --> 00:12:27,660 Now, this is often referred to as a headless mode 326 00:12:27,660 --> 00:12:30,330 because there is no graphical user interface. 327 00:12:30,330 --> 00:12:32,250 Management of these virtual machines then 328 00:12:32,250 --> 00:12:34,560 has to occur using a command line interface 329 00:12:34,560 --> 00:12:37,140 usually by remotely accessing the virtual machines 330 00:12:37,140 --> 00:12:39,210 over an SSH connection. 331 00:12:39,210 --> 00:12:42,900 Alternatively though, you can use the virsh command 332 00:12:42,900 --> 00:12:46,110 as an interactive shell to control the virtual machines. 333 00:12:46,110 --> 00:12:48,450 This stands for virtual shell. 334 00:12:48,450 --> 00:12:50,340 Now, there are various subcommands you can use 335 00:12:50,340 --> 00:12:52,230 with virsh. 336 00:12:52,230 --> 00:12:54,390 The help subcommand is going to be used to get help 337 00:12:54,390 --> 00:12:56,640 with the virsh command. 338 00:12:56,640 --> 00:12:58,920 The list subcommand is going to be used to get a list 339 00:12:58,920 --> 00:13:02,790 of recognized virtual machines by the virsh command. 340 00:13:02,790 --> 00:13:05,370 The shutdown VM subcommand is going to be used 341 00:13:05,370 --> 00:13:07,410 to gracefully shut down a virtual machine 342 00:13:07,410 --> 00:13:08,850 using this utility. 343 00:13:08,850 --> 00:13:10,650 The start virtual machine subcommand 344 00:13:10,650 --> 00:13:13,080 is going to be used to start a virtual machine. 345 00:13:13,080 --> 00:13:14,870 The reboot virtual machine subcommand 346 00:13:14,870 --> 00:13:17,520 is going to be used to reboot a virtual machine. 347 00:13:17,520 --> 00:13:20,430 The create and then an XML file name subcommand 348 00:13:20,430 --> 00:13:23,550 is going to create a virtual machine from an XML file 349 00:13:23,550 --> 00:13:25,920 that contains all the parameters you need. 350 00:13:25,920 --> 00:13:28,590 The save virtual machine file name subcommand 351 00:13:28,590 --> 00:13:31,140 is going to save the current state of that virtual machine 352 00:13:31,140 --> 00:13:33,660 with the given file name that you specified. 353 00:13:33,660 --> 00:13:35,600 And the console virtual machine subcommand 354 00:13:35,600 --> 00:13:38,130 is going to open up a console to that virtual machine, 355 00:13:38,130 --> 00:13:40,410 so you can interact with it directly. 356 00:13:40,410 --> 00:13:43,080 Now, Linux virtualization solutions are usually built 357 00:13:43,080 --> 00:13:47,190 on top of libvirt, or libvirt, 358 00:13:47,190 --> 00:13:50,430 which is an application programming interface or API 359 00:13:50,430 --> 00:13:52,080 that provides the software building blocks 360 00:13:52,080 --> 00:13:55,470 for developers to write their own virtualization solutions. 361 00:13:55,470 --> 00:13:57,930 These solutions can also be composed of a DAMON 362 00:13:57,930 --> 00:13:59,280 and a management interface 363 00:13:59,280 --> 00:14:01,710 to have more of a client server model here. 364 00:14:01,710 --> 00:14:05,220 There are several hypervisors, including VMware's ESXi, 365 00:14:05,220 --> 00:14:10,220 KVM, and QEMU, that are all built using the libvirt 366 00:14:10,290 --> 00:14:12,060 as it provides a solid foundation 367 00:14:12,060 --> 00:14:14,220 for Linux based virtualization. 368 00:14:14,220 --> 00:14:17,700 For example, the virsh tool that we just talked about 369 00:14:17,700 --> 00:14:21,480 is actually part of the libvirt API tool set. 370 00:14:21,480 --> 00:14:22,350 Now, if you're using 371 00:14:22,350 --> 00:14:24,690 a graphical user based Linux distribution 372 00:14:24,690 --> 00:14:26,820 that has the known desktop environment, 373 00:14:26,820 --> 00:14:30,060 you can also use a graphical user interface based way 374 00:14:30,060 --> 00:14:31,620 to manage your virtual machines 375 00:14:31,620 --> 00:14:35,640 known as Gnome virtual machine manager or VMM. 376 00:14:35,640 --> 00:14:37,890 The Gnome virtual machine manager utility 377 00:14:37,890 --> 00:14:40,440 can be used from managing connectivity to virtual machines 378 00:14:40,440 --> 00:14:42,930 and enable the deployment, management and removal 379 00:14:42,930 --> 00:14:44,310 of those virtual machines 380 00:14:44,310 --> 00:14:47,190 using a more intuitive graphical interface. 381 00:14:47,190 --> 00:14:51,390 You can download and install the virt-manager package 382 00:14:51,390 --> 00:14:53,400 if you want to be able to use VMM 383 00:14:53,400 --> 00:14:55,680 or the virtual machine manager. 384 00:14:55,680 --> 00:14:56,513 Wow. 385 00:14:56,513 --> 00:14:58,230 Now, I know that was a lot of information 386 00:14:58,230 --> 00:15:00,150 but the good news is that most of that 387 00:15:00,150 --> 00:15:01,140 should have been reviewed 388 00:15:01,140 --> 00:15:04,500 from your A+, Network+ and Security+ studies. 389 00:15:04,500 --> 00:15:06,540 The only really new things we discussed here 390 00:15:06,540 --> 00:15:07,813 are the different tools used in Linux 391 00:15:07,813 --> 00:15:10,350 to be able to create, install, setup 392 00:15:10,350 --> 00:15:13,320 and configure virtual machines, such as the file formats 393 00:15:13,320 --> 00:15:18,270 of OVF, JSON, YAML, and container images, 394 00:15:18,270 --> 00:15:20,370 the bootstrapping concepts that included things 395 00:15:20,370 --> 00:15:23,160 like Cloud-init, Anaconda and Kickstart 396 00:15:23,160 --> 00:15:25,200 as well as the Linux utilities that are used 397 00:15:25,200 --> 00:15:29,460 with virtual machines such as the virsh, libvirt, 398 00:15:29,460 --> 00:15:31,233 and VMM utilities.