1 00:00:00,000 --> 00:00:07,100 Hi, Let us understand about 2 00:00:07,100 --> 00:00:14,000 Flow control, the important building block of the template is this flow control and it will be achieved 3 00:00:14,000 --> 00:00:17,533 using if else statement. This is very similar to the 4 00:00:17,533 --> 00:00:21,566 If else statements we have in any other languages where 5 00:00:21,566 --> 00:00:28,432 The condition will be evaluated using the pipeline and it will be used along with the if or elseif 6 00:00:28,433 --> 00:00:33,333 conditions. If the condition gets to true, it will be getting into that particular block 7 00:00:33,333 --> 00:00:37,699 And the statements within the block will get executed, if the condition fails 8 00:00:37,700 --> 00:00:41,400 It's going to move on to the next condition that is else if 9 00:00:41,400 --> 00:00:46,166 Again, there is going to be another pipeline or condition evaluation that will be evaluated. 10 00:00:46,166 --> 00:00:53,632 If that evaluated to true, then the blocks within that will get evaluated and we will be having a else condition 11 00:00:53,633 --> 00:01:00,266 where if all the above conditions failed, then the statements within the else conditions will be executed. 12 00:01:00,266 --> 00:01:03,066 That's like a default keys and elseif, 13 00:01:03,066 --> 00:01:09,332 else conditions are optional and only if statement is sufficient enough, most of the places we 14 00:01:09,333 --> 00:01:15,099 will be using that to verify the conditions and execute a few set of statements. 15 00:01:15,100 --> 00:01:18,200 Let's have a quick check on what all situations 16 00:01:18,200 --> 00:01:21,066 The condition would be evaluated as false. 17 00:01:21,066 --> 00:01:28,332 If the pipeline is evaluated, as the following values, it will be considered as false, like boolean 18 00:01:28,333 --> 00:01:33,966 false or a numerical value of zero, empty string or nil value. 19 00:01:33,966 --> 00:01:41,666 That is like null and any empty collection of map, slice, tuple, dictionary or an array 20 00:01:41,666 --> 00:01:45,366 Now let us see a small example. Here I do have the template. 21 00:01:45,366 --> 00:01:49,499 Let me get into the sample template that we had created. Here 22 00:01:49,500 --> 00:01:53,866 I am going to update the values, within the values file 23 00:01:53,866 --> 00:01:56,932 Already we do have a key called infra, within that 24 00:01:56,933 --> 00:01:59,999 I do have a collection of key and value. 25 00:02:00,000 --> 00:02:02,800 I do have the keys like Zone and region. 26 00:02:02,800 --> 00:02:09,066 I'm going to evaluate this specific key region, whether it is equal to a specific value or not. 27 00:02:09,066 --> 00:02:13,232 If it is evaluated as true, I will be taking some decision. 28 00:02:13,233 --> 00:02:16,633 Let me go ahead and change the templates, within the template 29 00:02:16,633 --> 00:02:18,933 Let me go ahead and edit it. 30 00:02:18,933 --> 00:02:23,866 I'm going to remove the other values that we added for the test purpose. 31 00:02:23,866 --> 00:02:32,432 Here I'm going to add a condition if, and I can have the logical conditions like equal, not equal, all possible conditions available. 32 00:02:32,433 --> 00:02:43,466 I'm going to evaluate for values.infra.region and that should be equal to us-e 33 00:02:43,466 --> 00:02:48,532 If this condition succeeded, then I'm going to add another key value pair true 34 00:02:48,533 --> 00:02:50,299 Then I need to end the condition. 35 00:02:50,300 --> 00:02:52,133 I don't want any if else condition. 36 00:02:52,133 --> 00:02:56,766 So I'm going to end it with double open bracket and close bracket. 37 00:02:56,766 --> 00:03:01,366 Observe very carefully the indentation should start at this specific location. 38 00:03:01,366 --> 00:03:03,832 or else its going to give error messages. 39 00:03:03,833 --> 00:03:05,199 We will try out those scenarios 40 00:03:05,200 --> 00:03:11,833 as well. I returned the changes let me go ahead and do a dry run using helm install 41 00:03:11,833 --> 00:03:13,866 dry run and in the debug mode 42 00:03:13,866 --> 00:03:19,666 I'm going to give a name to this particular release and execute the mychart resources. 43 00:03:19,666 --> 00:03:22,232 So the value it evaluated to be true. 44 00:03:22,233 --> 00:03:25,166 So what happened it printed it as true. 45 00:03:25,166 --> 00:03:29,266 Now, let me go ahead and change the value. 46 00:03:29,266 --> 00:03:34,766 I'm changing it to us-w 47 00:03:34,766 --> 00:03:39,599 Now, let me go ahead and do a dry run 48 00:03:39,600 --> 00:03:45,200 It should not print the value ha:true, because the condition did not get evaluated, the same 49 00:03:45,200 --> 00:03:50,566 way I can have if else conditions as well, the very important thing to be noted in this specific 50 00:03:50,566 --> 00:03:54,532 condition is how to align this particular statement. 51 00:03:54,533 --> 00:03:56,899 Let's try out a few scenarios. 52 00:03:56,900 --> 00:04:02,200 And before that, I need to change the values so that the condition will get evaluated to be true. 53 00:04:02,200 --> 00:04:06,033 So I am changing it back to us-e 54 00:04:06,033 --> 00:04:10,766 Now, let me go ahead and execute the dry run. 55 00:04:10,766 --> 00:04:12,766 If you observe the result very carefully 56 00:04:12,766 --> 00:04:17,499 We do have an empty line over here and within YAML file empty lines 57 00:04:17,500 --> 00:04:18,866 It's not going to create a problem. 58 00:04:18,866 --> 00:04:24,499 But that is not advised to have, only the important thing that we need to take over here is the 59 00:04:24,500 --> 00:04:28,400 indentation. The indentation is done properly with two spaces. 60 00:04:28,400 --> 00:04:31,366 So it should work, but it is not recommended. 61 00:04:31,366 --> 00:04:33,299 Now, let's go ahead and test it out. 62 00:04:33,300 --> 00:04:38,000 What if we provide some indentation or some additional space in the template 63 00:04:38,000 --> 00:04:39,033 Let's check the result. 64 00:04:39,033 --> 00:04:43,433 Let me get into the templates. 65 00:04:43,433 --> 00:04:46,633 Let's try this out, how it's going to work. 66 00:04:46,633 --> 00:04:49,799 Let me go ahead and do the dry run. 67 00:04:49,800 --> 00:04:57,333 Yes. The indentation worked fine. The reason because let me get into the template. 68 00:04:57,333 --> 00:05:02,566 The condition will get evaluated and from this particular point, it's going to provide two indentation 69 00:05:02,566 --> 00:05:04,332 With this particular understanding 70 00:05:04,333 --> 00:05:07,399 Let me go ahead and do this. 71 00:05:07,400 --> 00:05:11,900 Here, the key value pair will be indented with two more additional spaces. 72 00:05:11,900 --> 00:05:17,200 And that is not a valid YAML file because it should be under another key. 73 00:05:17,200 --> 00:05:24,200 Now, let me go ahead and do a dry run on this particular case as well, and see how the error will be. 74 00:05:24,200 --> 00:05:28,700 So here I got an error because values are not allowed in this context. 75 00:05:28,700 --> 00:05:34,033 The reason why I am demonstrating various options most of the time the mistakes happen in this specific 76 00:05:34,033 --> 00:05:38,933 area of indentation while using the conditional statements. 77 00:05:38,933 --> 00:05:43,433 Now, let me go ahead and correct this. 78 00:05:43,433 --> 00:05:44,566 So this should work. 79 00:05:44,566 --> 00:05:50,666 But at the same time, let's understand how to remove the blank line that we had got, so that can be 80 00:05:50,666 --> 00:05:56,032 removed using a minus symbol over here and a minus symbol over here. 81 00:05:56,033 --> 00:06:01,166 That means the new line in that specific location should be removed. 82 00:06:01,166 --> 00:06:06,332 So there will be a new line at the starting of this particular condition evaluation and that will be removed. 83 00:06:06,333 --> 00:06:10,433 And in the end, also, there will be a new line condition and that will be removed. 84 00:06:10,433 --> 00:06:14,933 Now, let me go ahead and do a dry run. 85 00:06:14,933 --> 00:06:16,933 Now, there is no new line character. 86 00:06:16,933 --> 00:06:19,799 And everything is working fine. Now let's see 87 00:06:19,800 --> 00:06:23,166 What if I deleted the new line in the end as well 88 00:06:23,166 --> 00:06:25,199 That should also be not done. 89 00:06:25,200 --> 00:06:28,200 Anyway, let's go ahead and try it out. 90 00:06:28,200 --> 00:06:37,766 So here the end, I'm going to remove the existing new line so that can be provided by adding a dash over here. 91 00:06:37,766 --> 00:06:38,632 So what will happen 92 00:06:38,633 --> 00:06:45,633 It'll remove the starting new line as well as the end new line and this ha it will try to add over here along 93 00:06:45,633 --> 00:06:48,533 with this specific project code 94 00:06:48,533 --> 00:06:53,499 where that will fail because that's not a valid yaml file. 95 00:06:53,500 --> 00:06:57,700 Let's go ahead and do the dry run. 96 00:06:57,700 --> 00:07:01,300 yes the parsing failed because that's not a valid yaml file 97 00:07:01,300 --> 00:07:04,066 So what happened was. 98 00:07:04,066 --> 00:07:10,699 After evaluation, this ha:true will get added next to project code and the value. 99 00:07:10,700 --> 00:07:14,233 So it's going to have another colon and that will fail. 100 00:07:14,233 --> 00:07:16,833 So this is not a right option as well. 101 00:07:16,833 --> 00:07:25,533 So the right thing to do is remove the new line in the beginning of each condition as well as in the end. 102 00:07:25,533 --> 00:07:31,299 And have the indentation and the location from where the condition is getting executed the same place 103 00:07:31,300 --> 00:07:37,600 The text within that will also get aligned in case if we have this particular condition evaluation in 104 00:07:37,600 --> 00:07:40,900 the beginning, then properly the indentation should be provided. 105 00:07:40,900 --> 00:07:42,733 So this is the right way to do. 106 00:07:42,733 --> 00:07:45,166 Finally, let me go ahead and do the dry run 107 00:07:45,166 --> 00:07:51,466 And the reason why I am not installing and uninstalling, the dry run is sufficient enough to evaluate the condition 108 00:07:51,466 --> 00:07:54,866 and how that particular manifest file would look like. 109 00:07:54,866 --> 00:07:58,966 So we have seen what are the different options to use the if else conditions 110 00:07:58,966 --> 00:08:04,799 And the important thing to take care of removing the new line as well as what to do and what not to 111 00:08:04,800 --> 00:08:06,900 do while adding the conditional statements.