WEBVTT 1 00:00.000 --> 00:04.240 So friends in the previous video we discussed how we can utilize loops within 2 00:04.240 --> 00:05.680 our Gen 2 templates. 3 00:05.680 --> 00:09.920 What we now want to do is to see how we can use conditional logic and how we're 4 00:09.920 --> 00:10.400 going to learn 5 00:10.400 --> 00:14.800 how to do that. Well the best place to go as always is to the documentation so 6 00:14.800 --> 00:15.120 that's what 7 00:15.120 --> 00:19.000 we're going to do. So again if we just happen to search for Gen 2 documentation 8 00:19.000 --> 00:19.760 let's click this 9 00:19.760 --> 00:24.440 top link right here and this time we're going to once again go to our control 10 00:24.440 --> 00:26.080 structures right here 11 00:26.080 --> 00:29.650 and if we just scroll on down a little bit we're going to come to this part 12 00:29.650 --> 00:30.560 right here. So what WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 12 00:29.650 --> 00:30.560 right here. So what 13 00:30.560 --> 00:34.430 we actually see here is the F statement. Now it says here that F statement in 14 00:34.430 --> 00:36.000 Ginger is comparable 15 00:36.000 --> 00:40.190 with the F statement in Python. So once again if you are familiar with Python 16 00:40.190 --> 00:41.280 you'll have a big 17 00:41.280 --> 00:45.470 advantage with respect to these Gen 2 templates. Now if you just happen to have 18 00:45.470 --> 00:46.480 familiarity with 19 00:46.480 --> 00:50.850 Ansible the conditional logic would be invoked via the when keyword which again 20 00:50.850 --> 00:51.840 just like the loop 21 00:51.840 --> 00:56.100 keyword is ultimately acting as a front end a simplified front end for the 22 00:56.100 --> 00:57.520 underlying Python code 23 00:57.520 --> 01:01.660 with thin Ansible. Ginger to just happens to express this construct a lot more WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 23 00:57.520 --> 01:01.660 with thin Ansible. Ginger to just happens to express this construct a lot more 24 01:01.660 --> 01:03.120 like the native Python. 25 01:03.120 --> 01:06.020 Now we're going to notice quite a lot of the same things that we saw with 26 01:06.020 --> 01:07.200 respect to our loops once 27 01:07.200 --> 01:11.060 again the control structure is going to have the similar syntax we're going to 28 01:11.060 --> 01:12.080 have our curly brace 29 01:12.080 --> 01:14.910 as well as our percentage sign. The difference here is that we're going to use 30 01:14.910 --> 01:15.840 a different keyword 31 01:15.840 --> 01:19.330 this time instead of the four keyword of course we're going to be using the F 32 01:19.330 --> 01:20.320 keyword and again 33 01:20.320 --> 01:24.320 the close off the control structure with percentage and curly brace. Now this 34 01:24.320 --> 01:25.120 part here might like a 35 01:25.120 --> 01:28.600 little bit strange it just says if users and let me just not write over that 36 01:28.600 --> 01:29.920 let's try that again. 37 01:29.920 --> 01:33.640 In the case here what we're actually asking is a billion value that this means WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 37 01:29.920 --> 01:33.640 In the case here what we're actually asking is a billion value that this means 38 01:33.640 --> 01:34.960 if users is defined 39 01:34.960 --> 01:40.870 basically if we have users i.e. a users key within our variables that is going 40 01:40.870 --> 01:42.560 to be denoted as true 41 01:42.560 --> 01:46.310 and just like we talked about conditionals in a previous skill that means that 42 01:46.310 --> 01:47.040 the underlying 43 01:47.040 --> 01:50.750 code is going to execute. Now once again much like with respect to our loops we 44 01:50.750 --> 01:51.600 have to manually 45 01:51.600 --> 01:55.650 close them off with enginger to and the same thing is true with respect to our 46 01:55.650 --> 01:56.000 if statements 47 01:56.000 --> 02:00.070 we're going to have to use the end F keywords to effectively terminate any of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 47 01:56.000 --> 02:00.070 we're going to have to use the end F keywords to effectively terminate any of 48 02:00.070 --> 02:00.960 these F blocks. 49 02:00.960 --> 02:05.320 Now look at this right here this example it says if users so pretty much if we 50 02:05.320 --> 02:07.440 have a users key defined 51 02:07.440 --> 02:11.180 then we want to do an action. Now what is the action? Well the action is to 52 02:11.180 --> 02:12.800 loop through all 53 02:12.800 --> 02:17.100 of the users we see four user end users and that gives us access to the iter 54 02:17.100 --> 02:17.840 able element and then 55 02:17.840 --> 02:23.540 we can parse out the username then notice we close the four loop here which is 56 02:23.540 --> 02:24.880 this part here and the 57 02:24.880 --> 02:29.500 outer if statement which is actually containing the four loop is closed at the 58 02:29.500 --> 02:30.480 very end hopefully WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 58 02:29.500 --> 02:30.480 very end hopefully 59 02:30.480 --> 02:36.420 that makes sense basically this part here only actually happens inside of the f 60 02:36.420 --> 02:37.600 condition so we 61 02:37.600 --> 02:41.270 essentially wrap the f condition around it here is where we define the start 62 02:41.270 --> 02:42.240 and here is where we 63 02:42.240 --> 02:46.620 define the end. Now we can actually create more complex if statements you can 64 02:46.620 --> 02:47.520 use things like 65 02:47.520 --> 02:52.110 LF to specify other conditions if the first condition does not pass as well as 66 02:52.110 --> 02:52.880 a default else 67 02:52.880 --> 02:56.700 which will always execute for now we're not going to worry about that let's 68 02:56.700 --> 02:57.840 just dive in and look 69 02:57.840 --> 03:02.730 at a basic if statement in conjunction with our current ginger to template. So WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 69 02:57.840 --> 03:02.730 at a basic if statement in conjunction with our current ginger to template. So 70 03:02.730 --> 03:03.520 if we go into our 71 03:03.520 --> 03:08.140 host variables for example let's perhaps remove the nugget user from the wheel 72 03:08.140 --> 03:08.960 group okay let's just 73 03:08.960 --> 03:12.840 edit this and what it will do is I'll remove the wheel group okay so DD to 74 03:12.840 --> 03:14.000 remove and let's do the 75 03:14.000 --> 03:18.870 same thing for the yellow box we're going here DD to remove and just saving qu 76 03:18.870 --> 03:20.240 its so if you recall 77 03:20.240 --> 03:24.790 in Linux the wheel group is used to denote admin users basically people who 78 03:24.790 --> 03:26.240 have elevated privileges 79 03:26.240 --> 03:29.660 perform the pseudo command that type of thing now the examples that I have 80 03:29.660 --> 03:30.800 written up here are not WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 80 03:29.660 --> 03:30.800 written up here are not 81 03:30.800 --> 03:34.010 necessarily accurate with respect to the real world configurations on these 82 03:34.010 --> 03:34.880 devices we're just 83 03:34.880 --> 03:39.320 trying to manipulate data here but as per this particular example we can see 84 03:39.320 --> 03:40.320 the answerable user 85 03:40.320 --> 03:44.540 as a member of wheel so they do have elevated privileges as well as James 86 03:44.540 --> 03:46.160 however the nugget user 87 03:46.160 --> 03:49.620 just appears to be a regular user right now because we deleted that wheel 88 03:49.620 --> 03:51.360 membership similarly if we 89 03:51.360 --> 03:56.480 look at the yellow box very same thing is true here answerable is once again an 90 03:56.480 --> 03:57.520 elevated user 91 03:57.520 --> 04:02.050 or a user with elevated privileges should I say as well as is the nox account WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 91 03:57.520 --> 04:02.050 or a user with elevated privileges should I say as well as is the nox account 92 04:02.050 --> 04:03.200 but the nugget user 93 04:03.200 --> 04:07.050 once again doesn't have that wheel access so let's imagine in our configuration 94 04:07.050 --> 04:07.920 fair we wanted to 95 04:07.920 --> 04:11.930 write which users happen to be admin users but we would like to have a 96 04:11.930 --> 04:13.680 particular condition if they 97 04:13.680 --> 04:18.470 happen to be a member of the wheel group we want to run the test and the test 98 04:18.470 --> 04:20.320 is if the wheel happens 99 04:20.320 --> 04:25.060 to appear then we can perform a particular action we can say something like the 100 04:25.060 --> 04:25.840 user has 101 04:25.840 --> 04:30.320 elevated privileges otherwise they do not have elevated privileges so that's WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 101 04:25.840 --> 04:30.320 elevated privileges otherwise they do not have elevated privileges so that's 102 04:30.320 --> 04:31.040 basically what we're 103 04:31.040 --> 04:35.290 going to try to do so let's go and check out our template right now go in and 104 04:35.290 --> 04:36.560 save them template 105 04:36.560 --> 04:41.320 test.j2 so what I could do is I could say as I'm looking through my users I can 106 04:41.320 --> 04:42.240 add my control 107 04:42.240 --> 04:46.810 logic so color brace percent and here is my condition if and then within my 108 04:46.810 --> 04:47.680 quotation marks 109 04:47.680 --> 04:53.050 I'll test if wheel is in the user dot groups and then I'll close off my control 110 04:53.050 --> 04:54.080 structure with 111 04:54.080 --> 04:59.010 percentage color brace then I can add in some new text perhaps I can say the 112 04:59.010 --> 05:00.960 users on my system WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 112 04:59.010 --> 05:00.960 users on my system 113 05:00.960 --> 05:06.160 with elevated priffs are and then we pass in the username and then we specify 114 05:06.160 --> 05:06.640 which groups 115 05:06.640 --> 05:10.420 they happen to be belonging to and the hard part here might be noticing where 116 05:10.420 --> 05:11.520 abouts to be closed 117 05:11.520 --> 05:16.930 off the if statement so let's work our way out to in here is the first first 118 05:16.930 --> 05:18.240 statement and that is 119 05:18.240 --> 05:22.160 closed off here at the end and then we have our inner first statement here 120 05:22.160 --> 05:23.840 which is closed off here 121 05:23.840 --> 05:28.640 now inside of the first statement here we have our if statement which means we 122 05:28.640 --> 05:29.280 actually want to 123 05:29.280 --> 05:33.160 have the if statement in between right here see it's kind of like a mirror WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 123 05:29.280 --> 05:33.160 have the if statement in between right here see it's kind of like a mirror 124 05:33.160 --> 05:34.320 reverse so what we want 125 05:34.320 --> 05:38.620 to do here is I'm going to go in between these two control structures and ender 126 05:38.620 --> 05:40.400 color brace percentage 127 05:40.400 --> 05:45.840 end if so if I press escape right and quit let's clear the screen and let's try 128 05:45.840 --> 05:46.720 rerunning that 129 05:46.720 --> 05:50.700 playbook and to enter and we can see the configurations that have been applied 130 05:50.700 --> 05:51.680 so let's go and check 131 05:51.680 --> 05:56.030 the config test file and check out the result it says there are users in fact 132 05:56.030 --> 05:56.960 that's a typo there 133 05:56.960 --> 06:01.140 that should say their users on my system with elevated priffs are and we can WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 133 05:56.960 --> 06:01.140 that should say their users on my system with elevated priffs are and we can 134 06:01.140 --> 06:02.160 see the answer will 135 06:02.160 --> 06:06.000 use it as well as the grip and in fact what we've done here notice we actually 136 06:06.000 --> 06:07.040 have a repetition 137 06:07.040 --> 06:11.050 of this statement the users on my system with elevated privileges that is 138 06:11.050 --> 06:12.080 because this statement 139 06:12.080 --> 06:16.040 here is actually also within the loop so it's being printed twice let's 140 06:16.040 --> 06:17.440 actually modify that and 141 06:17.440 --> 06:20.340 this is actually good to see because very often this is how you actually do 142 06:20.340 --> 06:21.440 these ginger templates 143 06:21.440 --> 06:26.480 you test it out before you actually deploy and you notice that there are some 144 06:26.480 --> 06:27.520 slight problems 145 06:27.520 --> 06:31.380 and what do you do just like a look you just iterate and iterate until it is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 145 06:27.520 --> 06:31.380 and what do you do just like a look you just iterate and iterate until it is 146 06:31.380 --> 06:33.200 correct so this part here 147 06:33.200 --> 06:38.080 as we can see is actually below therefore inside of a for loop so what I will 148 06:38.080 --> 06:39.200 do here is let's just 149 06:39.200 --> 06:43.680 remove this statement we don't need that and I'll just say the users on my 150 06:43.680 --> 06:44.960 system with elevated 151 06:44.960 --> 06:48.990 priffs are and that is now outside of the for loop unless you delete the one 152 06:48.990 --> 06:49.840 that is inside 153 06:49.840 --> 06:54.880 so if I press escape colon write and quits clear the screen add it up and rerun 154 06:54.880 --> 06:55.600 the playbook 155 06:55.600 --> 06:59.520 okay there's a changes in play let's go and verify so go into yellow box let's 156 06:59.520 --> 06:59.840 cat the 157 06:59.840 --> 07:04.040 config test this looks a lot better now it just says the users on my system WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 157 06:59.840 --> 07:04.040 config test this looks a lot better now it just says the users on my system 158 07:04.040 --> 07:05.120 with elevated priffs 159 07:05.120 --> 07:09.520 are and we see the answer will user and the groups to which answer belong to 160 07:09.520 --> 07:10.960 answer will and will 161 07:10.960 --> 07:14.580 similarly we also see Knox has elevated priffs and we see Knox's group 162 07:14.580 --> 07:15.280 membership 163 07:15.280 --> 07:19.560 Knox wheel and programming notice nowhere now because of that conditional 164 07:19.560 --> 07:20.240 statement 165 07:20.240 --> 07:24.240 do we actually see the nugget user and we should expect to see the same thing 166 07:24.240 --> 07:25.280 on the blue box 167 07:25.280 --> 07:29.750 so go to blue box and we'll cat the temp config test file enter check this out 168 07:29.750 --> 07:30.800 right here exactly WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 168 07:29.750 --> 07:30.800 right here exactly 169 07:30.800 --> 07:35.390 as we wanted to see the users on my system with elevated priffs are the answer 170 07:35.390 --> 07:36.000 will user with 171 07:36.000 --> 07:39.550 the corresponding groups as well as the James user with the corresponding 172 07:39.550 --> 07:40.480 groups once again 173 07:40.480 --> 07:43.720 and excluding that nugget user because of that conditional logic.