Serverless functions are on-demand computational concepts. So, there has to be an event that needs to trigger a Lambda function so that the entire computational process is started. AWS Lambda has several events which can act as a trigger. Almost all services of AWS can act as AWS Lambda's triggers. Here is the list of services that you can use for generating events for Lambda to respond to:

• API Gateway
• AWS IoT
• CloudWatch Events
• CloudWatch Logs
• CodeCommit
• Cognito Sync Trigger
• DynamoDB
• Kinesis
• S3
• SNS

The triggers page of AWS Lambda looks like this:

Let's take a look at some of the following important and widely-used triggers that are available, and understand how they can be leveraged as FaaS in the serverless paradigm. They are as follows:

• API Gateway: This trigger can be used to create efficient, scalable, and serverless APIs. One scenario...

Lambda functions are the core operating parts of a serverless architecture. They contain the code which is supposed to be executed. These functions are executed whenever the trigger attached to it has been set off. We have already learned about some of the most popular Lambda triggers in the previous section.

Whenever a Lambda function is triggered, it creates a container with the respective settings set by the user. We'll learn more about the container in our next section.

The spinning up of containers takes a bit of time, which may result in a latency whenever a fresh invocation of a Lambda function is done, as it takes time to set up the environment and bootstrap the settings mentioned by the user in the Advanced settings tab. So, to overcome this latency, AWS thaws a container for some time for reuse in case of another Lambda invocation within the thawing...

For understanding the concept of functions being executed as/inside containers, we need to properly understand the concept of containers. To cite the definition of a container from the Docker documentation (https://www.docker.com/what-docker):

What is available for both Linux and Windows based applications; containerized software will always run the same, regardless of the environment.

Containers isolate software from its surroundings (for example, differences between development and staging environments) and help reduce conflicts between teams running different software on the same infrastructure.

So, the concept of containers is that they are self-sustainable isolated...

In this section, we will go through the ways of configuring Lambda functions and understand all the settings in great detail. Like in the previous section, we will learn about each configuration and its settings, as follows:

1. You can go to the page of AWS Lambda by selecting it from the drop-down menu that is present in the top-left corner of the AWS console. This can be done as follows:

2. Once the Lambda option is selected, it redirects the user to the AWS Lambda console, which looks something like this:

3. For creating a function, you need to click on the orange Create a function button on the right. This will open a console for the function creation. This looks something like this:

4. Let's create a function from scratch in order to understand the configurations better. So, for doing that, click on the Author from scratch button on the top-right...

Just like every other software system and programming paradigm, proper testing of Lambda functions and serverless architectures is very important before deploying into production. We will try to understand the testing of Lambda functions in the following points:

1. In the top-most bar of the Lambda console, one can observe the Save and test option, which is represented by an orange button. This button saves the Lambda function and then runs the configured tests on that function. This looks something like this in the console:

2. Also, in the same bar, there exists a drop-down menu that reads Select a test event…. This contains a list of testing events available for testing Lambda functions. The drop-down looks like this:

3. Now, for further configuration of test events for the Lambda function, the user needs to select the Configure test events option...

The concept of the Version Control System (VCS) is for controlling and managing versions of code. This functionality is available directly from the main Lambda console. Let's try and learn how to version our Lambda functions:

1. The first option in the Actions drop-down in the Lambda console is the Publish new version option. This option can be seen here:

2. When the Publish new version option is selected, the versioning popup of the Lambda console would be seen on the console. This would ask about the name for the new version of your Lambda function. The popup looks something like this:

3. After clicking the Publish button, you will be re-directed to the main Lambda console. The successfully created Lambda version in the console looks something like this:

4. In the bottom half of the page, the following message can be noticed: Code and handler editing...

Lambda functions that have external libraries as dependencies can be packaged as deployment packages and be uploaded into the AWS Lambda console. This is very similar to creating a virtual environment in Python. So in this section, we shall learn and understand the process of creating Python deployment for using in the Lambda functions. We shall try and understand the process of creating deployment packages in detail, as follows:

1. Deployment packages are generally in the format of ZIP packages. The contents of the ZIP package is exactly the same as a normal library of any programming language.
2. The package structure should be such that the library folders and the function file are in the same destination or in the same hierarchy inside the folder structure of the deployment package. The layout looks something like this:

3. The Python libraries can...

In this chapter, we have learned the concepts of how triggers work for AWS Lambda and how to select triggers depending on the problem statement and time intervals, in case of cron job triggers. We understood what Lambda functions are, along with understanding their functionalities and settings related to memory, VPCs, security, and fault tolerance. We also learned about the way container reuse is done under the hood specifically for AWS Lambda. Then, we covered event-driven functions and how they are implemented under the hood, the concept of containers, and their uses and applications in the domain of software engineering in general. Most importantly, from the concepts we learned regarding containers, we can now appreciate the options for choosing containers for running the Lambda functions.

After that, we talked about all the configuration settings available in the AWS...