1 00:00:00,690 --> 00:00:06,900 In this video, we are going to see lambda function code and the best practices related to the Lambda 2 00:00:06,900 --> 00:00:07,740 Lifecycle. 3 00:00:08,580 --> 00:00:12,810 Lambda runs instance of your function to process events. 4 00:00:13,080 --> 00:00:20,640 You can invoke your function directly using the Lambda API or you can configure as an A service or resources 5 00:00:20,640 --> 00:00:22,440 in order to invoke your function. 6 00:00:23,100 --> 00:00:30,000 You can find in the image on the slide, which is the lambda function with Node.js version is you can 7 00:00:30,000 --> 00:00:37,680 see that we have a lambda function name that we export in the handle method and we have defined function 8 00:00:37,680 --> 00:00:40,710 which has event, context and callback parameters. 9 00:00:42,030 --> 00:00:48,510 With these parameters, we develop actual business function and after that perform some callback operations 10 00:00:48,510 --> 00:00:52,680 that can be returned in response or not response for asynchronous invocations. 11 00:00:53,740 --> 00:00:59,800 Full Lambda function has called to process the events that you pass into the function or that other 12 00:01:00,250 --> 00:01:03,520 services sent to the function with an object. 13 00:01:04,600 --> 00:01:10,060 The event object contains all the information about the event that triggered this lambda function. 14 00:01:10,210 --> 00:01:16,780 For example, if lambda invokes from the API gateway, then an HTTP request will be the information 15 00:01:16,780 --> 00:01:17,560 of event. 16 00:01:18,730 --> 00:01:27,190 The context object contains info about the runtime or lambda functions is executing in and after that 17 00:01:27,190 --> 00:01:30,070 we do all work inside our lambda function. 18 00:01:30,070 --> 00:01:37,390 We simply call the callback function with the results or the error and will respond to the HTTP request 19 00:01:37,420 --> 00:01:41,800 with it if we are invoking synchronous lambda function. 20 00:01:42,450 --> 00:01:48,420 So as you can see that there are several key concepts when writing lambda function code like event, 21 00:01:48,690 --> 00:01:54,930 you can see on the slide we have an event trigger execution, environment layer and so on. 22 00:01:54,930 --> 00:01:58,440 There is lots of key concepts when writing the lambda function. 23 00:01:58,620 --> 00:02:02,370 So let's see these key concepts for our lambda function. 24 00:02:02,580 --> 00:02:10,110 So the first, first of all, we should define the runtime so we select the runtime as part of configuring 25 00:02:10,110 --> 00:02:14,130 the function and the lambda loads and the runtime one. 26 00:02:14,130 --> 00:02:15,660 Initializing the environment. 27 00:02:15,660 --> 00:02:22,140 You can think lambda is the code container and when the lambda invocation happens, lambda sitting up 28 00:02:22,590 --> 00:02:24,150 is a container with that runtime. 29 00:02:24,150 --> 00:02:30,720 So runtime is very important and several runtimes that can be configured during the lambda. 30 00:02:31,890 --> 00:02:39,150 So after we write the function, when we are writing the function, the another key concept is handler 31 00:02:39,150 --> 00:02:39,750 method. 32 00:02:40,080 --> 00:02:43,470 Our function runs starting at the handle method. 33 00:02:43,530 --> 00:02:48,000 It is a best practice to separate the lambda handle from your business logic. 34 00:02:48,000 --> 00:02:56,220 So you should be separate your, for example, database connections and other pair loading operations 35 00:02:56,340 --> 00:02:57,780 from the handle method. 36 00:02:57,810 --> 00:03:00,960 Handle method should be only include your business logic. 37 00:03:00,960 --> 00:03:06,360 This is the best practice when writing lambda functions and another key concept is function. 38 00:03:06,690 --> 00:03:09,630 A function is a resource that you can invoke to run your code. 39 00:03:09,630 --> 00:03:15,990 In Lambda, a function has to code process the events that you pass into the function or that other 40 00:03:16,410 --> 00:03:18,210 services sent to the function. 41 00:03:20,190 --> 00:03:23,100 We can say that another key concept is triggered. 42 00:03:23,190 --> 00:03:27,120 A trigger is the resource or configuration that invokes a lambda function. 43 00:03:27,240 --> 00:03:33,210 Triggers includes a services that you can configure to invoke a function or event source mapping. 44 00:03:33,690 --> 00:03:39,450 An event source mapping is a resource in lambda that reads items from a stream or queue and invokes 45 00:03:39,450 --> 00:03:40,290 a function. 46 00:03:40,380 --> 00:03:45,540 This is the invoking lambda functions and using lambda with other services. 47 00:03:46,110 --> 00:03:49,530 And of course we have an event as a key concept. 48 00:03:49,650 --> 00:03:55,800 An event is a JSON formatted document that contains data for a lambda function in order to process. 49 00:03:56,100 --> 00:04:02,310 So the runtime converts the events to an object and passes into the your function code. 50 00:04:02,820 --> 00:04:08,280 When you invoke a function, you determine the structure and contents of the event. 51 00:04:08,400 --> 00:04:17,010 So if we call back to the previous slide, when a function is triggering from somewhere in a list, 52 00:04:17,040 --> 00:04:20,130 this event object we can see in the function. 53 00:04:20,130 --> 00:04:24,540 This event object will be including all the information as a JSON format. 54 00:04:24,540 --> 00:04:30,180 It is very important and we will see in the upcoming section how the event will be load and how we can 55 00:04:30,180 --> 00:04:34,290 get the parameters values from the event object into our lambda function. 56 00:04:34,440 --> 00:04:40,940 But basically this event is a JSON format document and contains all of the data, a lambda, which is 57 00:04:41,040 --> 00:04:42,990 services from the process. 58 00:04:43,650 --> 00:04:48,570 So now the another key concept is execution environment. 59 00:04:48,720 --> 00:04:54,570 An execution environment provides a secure and isolated runtime environment for our lambda function, 60 00:04:54,900 --> 00:05:00,630 an execution environment, manage the processes and resources that are required to run the function. 61 00:05:00,720 --> 00:05:05,970 So when Lambda is invoked, invoke invoking from the other services. 62 00:05:05,970 --> 00:05:11,970 The concurrent lambda invocations can be happened and these are all execution environments isolated 63 00:05:11,970 --> 00:05:13,500 between each other. 64 00:05:14,900 --> 00:05:19,370 And now we can continue with the key concept of the Lambda function code. 65 00:05:19,550 --> 00:05:22,310 Another key key concept is layer. 66 00:05:22,580 --> 00:05:28,760 A lambda layer is a zip file archive that contains additional code or other content. 67 00:05:29,000 --> 00:05:33,890 A layer can contain libraries, a custom runtime data or configuration files. 68 00:05:34,310 --> 00:05:39,950 Lambda layers provide a convenient way to package libraries and other dependencies that you can use 69 00:05:39,950 --> 00:05:41,270 with your lambda function. 70 00:05:41,480 --> 00:05:47,000 Using layers reduce the size of the uploaded deployment archives and makes it faster to deploy your 71 00:05:47,000 --> 00:05:47,540 code. 72 00:05:47,540 --> 00:05:50,600 So this is the best practice to using the layers. 73 00:05:50,600 --> 00:05:56,870 When you have additional packages and dependencies, you can combine into the layer and you can directly 74 00:05:56,870 --> 00:05:59,030 use the layer into lambda functions. 75 00:05:59,030 --> 00:06:00,470 When you are writing the code. 76 00:06:00,470 --> 00:06:06,200 By this way, you can reduce the size of upload deployment and also fast to deploy your lambda functions. 77 00:06:06,230 --> 00:06:12,620 There is also promote code sharing and separation of responsibilities so that you can iterate faster 78 00:06:12,620 --> 00:06:14,130 on writing business logics. 79 00:06:14,720 --> 00:06:17,360 And another key concept is concurrency. 80 00:06:17,450 --> 00:06:23,750 Concurrency is the number of requests that your function is solving at any given time when your function 81 00:06:23,750 --> 00:06:24,680 is invoked. 82 00:06:24,680 --> 00:06:28,220 Lambda provisions an instance of it is processed to event. 83 00:06:28,310 --> 00:06:31,940 When the function code finished running, it can handle another request. 84 00:06:32,030 --> 00:06:38,300 So if the function is invoked again, while a request is still being processed, another instance is 85 00:06:38,300 --> 00:06:41,240 provisioned and increasing the functions concurrency. 86 00:06:41,480 --> 00:06:44,300 So another key concept is the destination. 87 00:06:44,450 --> 00:06:49,970 A destination is an added resource where lambda can send events from asynchronous invocation. 88 00:06:50,150 --> 00:06:56,540 So you can configure a destination for events that fail processing like setting to the letter queue. 89 00:06:56,570 --> 00:06:59,510 The network is very important for lambda functions. 90 00:06:59,510 --> 00:07:06,740 If you your function execution phase, you can set into the data queue for the destination and understand 91 00:07:06,740 --> 00:07:08,570 and don't lose any invocation. 92 00:07:08,570 --> 00:07:13,730 Some services also support a destination for events that are successfully processed. 93 00:07:15,190 --> 00:07:19,840 So now I would like to talk about best practices related to the lifecycle. 94 00:07:20,870 --> 00:07:27,740 So we can say that best practices do take advantage of the environment, reduce and check the background 95 00:07:27,740 --> 00:07:35,180 processes have completed manage database connections pooling with a database proxy persist states data 96 00:07:35,180 --> 00:07:40,040 externally minimize deployment, package size and complexity of dependencies. 97 00:07:40,040 --> 00:07:46,910 So these are the main best practices when writing the lambda and Lambda Lifecycles. 98 00:07:47,120 --> 00:07:53,990 And we can say that configure functions with resource based policies because resource page policy grants 99 00:07:53,990 --> 00:07:56,360 permission to invoke your lambda functions. 100 00:07:56,360 --> 00:08:03,050 It is very important to policy when you are giving the grant permissions to invoking your lambda functions. 101 00:08:03,290 --> 00:08:06,830 It is important to configure function with the resource based policy. 102 00:08:07,070 --> 00:08:13,370 An execution role defines a functions permission to interact with resources, and another best practice 103 00:08:13,370 --> 00:08:15,650 is using environment variables. 104 00:08:15,650 --> 00:08:22,790 We can use environment variable in order to store secrets securely and adjust your functions behavior 105 00:08:22,790 --> 00:08:24,290 without updating your code. 106 00:08:24,380 --> 00:08:30,410 So an environment variable is a pair of string that are stored in a functions virgin specific configuration. 107 00:08:30,650 --> 00:08:36,380 We can configure the environment value on the Islam, the configuration section, the underlying invocation 108 00:08:36,380 --> 00:08:41,990 environment for the runtime provides additional libraries as well as the environment variables that 109 00:08:41,990 --> 00:08:44,130 you can access from your function code. 110 00:08:44,690 --> 00:08:49,520 So we can also create your own environment variables in order to use in your code. 111 00:08:49,520 --> 00:08:55,190 When you publish a version, the environment variables are locked for that version along with the other 112 00:08:55,190 --> 00:08:56,660 virgin specific configuration. 113 00:08:56,660 --> 00:09:02,050 So this is a very powerful feature, as you can see that we have also seen best practices of Islam, 114 00:09:02,120 --> 00:09:03,080 the function code. 115 00:09:03,320 --> 00:09:08,090 In the next video we are going to work through a lambda with a management console.