WEBVTT 00:00.360 --> 00:01.300 -In this lecture, 00:01.300 --> 00:04.280 we will take a look at the for_each meta argument 00:04.400 --> 00:06.000 and its uses in Terraform. 00:07.180 --> 00:10.040 In the previous lecture, we saw that when we use count, 00:10.180 --> 00:12.300 the resources are created as a list, 00:12.860 --> 00:15.780 and this can have undesirable results when updating them. 00:16.740 --> 00:18.460 One way to overcome this 00:18.460 --> 00:21.840 is to make use of the for_each argument insert of count, 00:22.300 --> 00:22.980 like this. 00:24.220 --> 00:28.700 Next, to set the value of file name to each element in the list, 00:28.980 --> 00:32.820 we can make use of the expression is.value like this. 00:34.020 --> 00:35.440 However, there's a catch. 00:36.100 --> 00:37.880 If we run Terraform plan now, 00:38.280 --> 00:39.380 we will see an error. 00:40.560 --> 00:44.080 The for_each argument only works with a map or a set. 00:44.760 --> 00:46.440 In the variables.tf file, 00:46.440 --> 00:49.840 we are currently making use of a list containing string elements. 00:51.320 --> 00:53.060 There are a couple of ways to fix this. 00:53.780 --> 00:57.420 Either change the variable called filename to the type set. 00:58.360 --> 00:59.600 In the variables lecture, 00:59.600 --> 01:01.940 we learned that a set is similar to a list, 01:02.160 --> 01:04.660 but it cannot contain duplicate elements. 01:05.640 --> 01:08.720 Once we change the variable type and then run Terraform plan, 01:09.260 --> 01:11.700 we should see that there are three files to be created. 01:13.220 --> 01:14.920 Another way to fix this error 01:15.140 --> 01:17.640 while retaining the variable type as a list 01:17.820 --> 01:19.980 is to make use of another built-in function. 01:20.820 --> 01:23.600 This time, we'll make use of the toset function, 01:23.760 --> 01:26.760 which will convert the variables from a list to a set. 01:28.120 --> 01:29.240 Once this is done, 01:29.240 --> 01:31.700 Terraform plan command should now work as expected. 01:33.400 --> 01:35.460 Now let us replicate the same scenario 01:35.460 --> 01:38.420 as the one we did earlier with the count meta argument 01:38.720 --> 01:43.760 and delete the first element with the value/slash/root pets.txt from the list. 01:44.980 --> 01:46.700 When we run Terraform plan now, 01:47.020 --> 01:49.860 we can see that only one resource is said to be destroyed, 01:50.160 --> 01:52.760 the file with the name pets.txt. 01:54.000 --> 01:56.080 The other resources will be untouched. 01:57.240 --> 01:58.700 To see how this is working, 01:58.700 --> 02:01.300 let us create an output variable called pets 02:01.420 --> 02:05.140 to print the resource details like we did with the example using count. 02:06.480 --> 02:08.040 From the Terraform output command, 02:08.040 --> 02:12.420 we can now see that the resources are stored as a map and not a list. 02:13.240 --> 02:16.080 When we use for_each instead of count, 02:16.280 --> 02:19.080 the resources are created as a map and not a list. 02:19.800 --> 02:23.460 This means that the resources are no longer identified by the index, 02:23.720 --> 02:27.120 thereby bypassing the issues that we saw when we use count. 02:28.120 --> 02:30.520 They are now identified by the keys 02:30.520 --> 02:33.780 which are file names/root/..txt 02:33.960 --> 02:36.300 and /root/cat.txt, 02:36.480 --> 02:39.940 which are used by the for_each argument in the configuration file. 02:41.180 --> 02:43.700 If we compare this to the earlier output 02:43.780 --> 02:45.660 that we got when we use count, 02:45.760 --> 02:48.580 we can see the difference in how the resources are created. 02:49.220 --> 02:54.360 The count option created it as a list and the for_each created it as a map. 02:55.320 --> 02:57.880 There are a few other meta arguments in Terraform 02:57.880 --> 03:01.300 such as provisioners, providers, backends, et cetera. 03:01.880 --> 03:03.880 We will see that later in this course. 03:05.260 --> 03:07.780 Now let's head over to the hands-on labs 03:07.780 --> 03:11.820 and practice working with the for_each meta argument in Terraform.