1 00:00:06,850 --> 00:00:12,180 In this lecture we discuss how to work with configuration data in Kubernetes. 2 00:00:12,220 --> 00:00:17,050 In the previous lecture we saw how to define environment variables in it pod definition file. 3 00:00:17,770 --> 00:00:23,350 When you have a lot of pod definition files it will become difficult to manage the environment data 4 00:00:23,350 --> 00:00:26,110 stored within the query files. 5 00:00:26,110 --> 00:00:32,500 We can take this information out of the pod definition file and manage it centrally using Configuration 6 00:00:32,500 --> 00:00:39,920 Maps. ConfigMaps are used to pass configuration data in the form of key value pairs in Kubernetes. 7 00:00:40,150 --> 00:00:44,020 When it pod is created inject the config map into the pod. 8 00:00:44,110 --> 00:00:50,380 So the key value pairs that are available as environment variables for the application hosted inside 9 00:00:50,380 --> 00:00:52,330 the container in the pod. 10 00:00:52,690 --> 00:00:56,220 There are two phases involved in configuring ConfigMaps. 11 00:00:56,260 --> 00:01:05,070 First create the ConfigMaps and second Inject them into the POD. Just like any other Kubernetes object. 12 00:01:05,070 --> 00:01:08,330 There are two ways of creating a configmap. 13 00:01:08,580 --> 00:01:16,140 The imperative way - without using a ConfigMap definition file and the Declarative way by using a Config 14 00:01:16,140 --> 00:01:17,960 map definition file. 15 00:01:18,180 --> 00:01:24,240 If you do not wish to create a configmap definition, you could simply use the kubectl create 16 00:01:24,300 --> 00:01:29,040 configmap command and specify the required arguments. 17 00:01:29,040 --> 00:01:32,420 Let's take a look at that first with this method. 18 00:01:32,520 --> 00:01:39,120 you can directly specify the key value pairs in the command line. To create a configMap of the given 19 00:01:39,120 --> 00:01:43,720 values, run the kubectl create configmap command. 20 00:01:43,920 --> 00:01:51,360 The command is followed by the config name and the option –from-literal. The from literal option is 21 00:01:51,360 --> 00:01:55,560 used to specify the key value pairs in the command itself. 22 00:01:55,560 --> 00:02:03,090 In this example, we are creating a configmap by the name app-config, with a key value pair APP_COLOR 23 00:02:03,180 --> 00:02:04,800 equals blue. 24 00:02:04,980 --> 00:02:12,310 If you wish to add additional key value pairs simply specify the from literal options multiple times. 25 00:02:12,360 --> 00:02:17,760 However this will get complicated when you have too many configuration items. 26 00:02:17,760 --> 00:02:22,280 Another way to input configuration data is through a file. 27 00:02:22,290 --> 00:02:28,880 Use the from file option to specify a path to the file that contains the required data. 28 00:02:29,130 --> 00:02:36,650 The data from this file is read and stored under the name of the file let us now look at the declarative 29 00:02:36,650 --> 00:02:37,520 approach. 30 00:02:37,700 --> 00:02:42,470 For this we create a definition file just like how we did for the pod. 31 00:02:42,560 --> 00:02:50,330 The file has apiVersion, kind, metadata and instead of spec, here we have “data”. 32 00:02:50,330 --> 00:02:57,050 The apiVersion is v1, kind is ConfigMap. Under metadata specify the name of the config 33 00:02:57,050 --> 00:02:57,870 map. 34 00:02:58,070 --> 00:03:05,930 We will call it app-config. Under data add the configuration data in a key-value format. Run the kubectl 35 00:03:05,930 --> 00:03:13,010 create command and specify the configuration file name. So that creates the app-config config 36 00:03:13,040 --> 00:03:15,630 map with the values we specified. 37 00:03:15,980 --> 00:03:22,690 You can create as many configmaps as you need in the same way for various different purposes. 38 00:03:22,700 --> 00:03:28,920 Here I have one for my application, other for mysql and another one for redis. 39 00:03:29,120 --> 00:03:36,260 So it is important to name the config maps appropriately as you will be using these names later while 40 00:03:36,260 --> 00:03:44,120 associating it with PODs. To view the configmaps, run the kubectl get configmaps command. This lists 41 00:03:44,210 --> 00:03:49,930 the newly created configmap named app-config. The describe configmaps command 42 00:03:49,940 --> 00:03:58,440 List the configuration data as well under the data section now that we have the config map created let 43 00:03:58,440 --> 00:04:07,030 us proceed with step 2 configuring it with a pod here I have a simple pod definition file that runs 44 00:04:07,060 --> 00:04:14,710 my simple web application to inject an environment variable add a new property to the container called 45 00:04:14,860 --> 00:04:23,620 envFrom. The envFrom property is a list, so we can pass as many environment variables as required. Each 46 00:04:23,680 --> 00:04:30,490 item in the list corresponds to a configMap item. Specify the name of the configmap we created earlier. 47 00:04:31,150 --> 00:04:38,470 This is how we inject a specific configmap from the ones we created before. Creating the pod definition 48 00:04:38,470 --> 00:04:48,290 file now creates a web application with a blue background. What we just saw was using configMaps to inject 49 00:04:48,310 --> 00:04:50,160 environment variables. 50 00:04:50,160 --> 00:04:56,970 There are other ways to inject configuration data into pods you can inject it as a single environment 51 00:04:56,970 --> 00:05:02,820 variable or you can inject the whole the data as files in a volume. 52 00:05:03,000 --> 00:05:08,880 We will look at some of these options in the coding exercises that accompany this lecture. 53 00:05:08,910 --> 00:05:15,900 So head over to the coding exercises section and practice viewing configuring and troubleshooting environment 54 00:05:15,900 --> 00:05:18,930 variables on a live Kubernetes environment.