1 00:00:00,178 --> 00:00:01,901 So outputs, let's talk about outputs. 2 00:00:01,901 --> 00:00:04,341 And that's actually a very popular exam question, 3 00:00:04,341 --> 00:00:05,493 so pay attention. 4 00:00:05,493 --> 00:00:07,481 The outputs section is optional 5 00:00:07,481 --> 00:00:09,700 but we can declare optional outputs 6 00:00:09,700 --> 00:00:11,693 and if we export these outputs, 7 00:00:11,693 --> 00:00:15,438 we will be able to import their values into other stacks 8 00:00:15,438 --> 00:00:17,415 and by stack I mean, CloudFormation templates. 9 00:00:17,415 --> 00:00:20,533 So you can start linking your CloudFormation templates. 10 00:00:20,533 --> 00:00:23,123 We can also view the outputs in the AWS Console 11 00:00:23,123 --> 00:00:25,110 or using the AWS CLI so it allows us 12 00:00:25,110 --> 00:00:28,685 to quickly retrieve the value of an outputs, 13 00:00:28,685 --> 00:00:31,041 straight from using the UI. 14 00:00:31,041 --> 00:00:33,706 In terms of example, for example 15 00:00:33,706 --> 00:00:36,484 you can have a network CloudFormation template 16 00:00:36,484 --> 00:00:39,070 and then you would export outputs 17 00:00:39,070 --> 00:00:42,818 that would be for example, the VPC ID and the Subnet IDs. 18 00:00:42,818 --> 00:00:44,511 And you would reuse those in to 19 00:00:44,511 --> 00:00:47,036 other CloudFormation templates. 20 00:00:47,036 --> 00:00:50,534 So it enables to do a cross stack collaboration 21 00:00:50,534 --> 00:00:52,349 where you let the experts handle 22 00:00:52,349 --> 00:00:54,789 their own parts of the VPC and the Subnet 23 00:00:54,789 --> 00:00:56,290 and you as a app developer, 24 00:00:56,290 --> 00:01:00,173 you just reference these values out of the box. 25 00:01:00,173 --> 00:01:01,133 Something you should know though, 26 00:01:01,133 --> 00:01:04,374 is that if you start using the CloudFormation outputs 27 00:01:04,374 --> 00:01:05,711 and they start being referenced 28 00:01:05,711 --> 00:01:07,985 from another CloudFormation stack, 29 00:01:07,985 --> 00:01:09,266 you cannot delete a stack 30 00:01:09,266 --> 00:01:12,012 that still has outputs being referenced somewhere else. 31 00:01:12,012 --> 00:01:13,904 So that's just something to know. 32 00:01:13,904 --> 00:01:16,306 Now if we look at an example of the outputs. 33 00:01:16,306 --> 00:01:19,408 In this one we are creating a SSH Security Group 34 00:01:19,408 --> 00:01:20,644 as part of the template. 35 00:01:20,644 --> 00:01:23,977 And so we export that value as an output 36 00:01:25,096 --> 00:01:28,196 and basically other templates will be able 37 00:01:28,196 --> 00:01:31,727 to get the value of that Security Group ID. 38 00:01:31,727 --> 00:01:33,339 So the syntax is pretty easy, 39 00:01:33,339 --> 00:01:35,400 we have the outputs section right here, 40 00:01:35,400 --> 00:01:38,147 and we have the name of the Security Group 41 00:01:38,147 --> 00:01:39,148 and we have the description, 42 00:01:39,148 --> 00:01:41,743 so the SSH Security Group for our Company. 43 00:01:41,743 --> 00:01:42,662 Here's the value, 44 00:01:42,662 --> 00:01:44,643 so we provide a reference of the Security Group 45 00:01:44,643 --> 00:01:47,672 where that was created within the resources. 46 00:01:47,672 --> 00:01:51,375 And then we have to specify this Export block right here, 47 00:01:51,375 --> 00:01:53,839 this is an optional block, if you don't specify it, 48 00:01:53,839 --> 00:01:55,480 then the value does not get exported 49 00:01:55,480 --> 00:01:57,375 and it will not be able to be imported. 50 00:01:57,375 --> 00:01:59,516 So when we specify the Export value, 51 00:01:59,516 --> 00:02:03,617 we can say okay, this value, this SSH Security Group ID, 52 00:02:03,617 --> 00:02:08,022 is going to be exported as the name SSH Security Group. 53 00:02:08,022 --> 00:02:09,731 So now how do we import the value? 54 00:02:09,731 --> 00:02:11,637 Well using a cross stack reference. 55 00:02:11,637 --> 00:02:12,980 And so we'll create a second template 56 00:02:12,980 --> 00:02:14,554 that leverages that security group. 57 00:02:14,554 --> 00:02:18,187 And for this we'll use the Fn Import Value function, 58 00:02:18,187 --> 00:02:19,401 interesting function. 59 00:02:19,401 --> 00:02:20,772 And we can't delete again, 60 00:02:20,772 --> 00:02:24,572 the previous stack until all this stack will be deleted. 61 00:02:24,572 --> 00:02:27,667 So if we look at this little snippet of code right here, 62 00:02:27,667 --> 00:02:30,492 we can see that for the security groups at the very bottom, 63 00:02:30,492 --> 00:02:33,705 there's a short hand syntax for import value 64 00:02:33,705 --> 00:02:36,928 and then we reference the exact same name as before, 65 00:02:36,928 --> 00:02:39,850 called SSH Security Group. 66 00:02:39,850 --> 00:02:41,440 So, just a reminder, 67 00:02:41,440 --> 00:02:45,219 before, we exported the value as SSH Security Group 68 00:02:45,219 --> 00:02:50,007 and here we import the value SSH Security Group. 69 00:02:50,007 --> 00:02:52,699 So, you know, outputs and exports are 70 00:02:52,699 --> 00:02:55,369 a very, very popular question at the exam. 71 00:02:55,369 --> 00:02:56,814 Especially, if they start asking you, 72 00:02:56,814 --> 00:02:58,319 how do you link CloudFormation templates? 73 00:02:58,319 --> 00:03:00,341 Or retrieve the value from one to another? 74 00:03:00,341 --> 00:03:01,504 So you should know about it. 75 00:03:01,504 --> 00:03:02,587 You should know about the syntax, 76 00:03:02,587 --> 00:03:05,002 and you should know about the import value function. 77 00:03:05,002 --> 00:03:06,153 So I hope that was helpful 78 00:03:06,153 --> 00:03:08,249 and I will see you in the next lecture.