Steps for Building a Lambda function
The lifecycle of Lambda function includes four necessary steps −
AWS Lambda function code can be written in following languages −
We can write code for AWS Lambda using the AWS console, AWS CLI, from Eclipse IDE, from Visual Studio IDE, serverless framework etc.
The following table shows a list of languages and the different tools and IDE that can be used to write the Lambda function −
Language IDE for Authoring Lambda Code
Go AWS Lambda Console
Deploying Lambda Code
Once you decide the language you want to write the Lambda function, there are two ways to deploy the code −
Directly write the code in AWS console
Zip or jar the files with all the files and dependencies However, remember that proper permission has to given to be given to the zip file.
Testing Lambda Code
Lambda Code can be tested for events inside the AWS Lambda console. It's also possible to test the Lambda function from the AWS cli and serverless cli. AWS console has also event data which can be used as sample events while testing AWS Lambda function.
Monitoring Lambda function
Monitoring of Lambda function can be done using the AWS CloudWatch. We can add necessary log messages in languages we choose and see the same in AWS CloudWatch.
To start writing Lambda function, there's pattern to be followed. The following are the main core concepts to be followed for writing a Lambda function −
Handler is a name of the AWS lambda function from where the execution starts. It appears in AWS console as shown below −
Notice that then we've changed the dereliction handler to another name and updated the same in the Handler −
Note that the way a handler is called differs from the languages selected as runtime.
Params passed to handler
still, the params passed are event, context and call back function as shown below −
If you observe the handler function.Params Passed Event parameter has all the details for the trigger used.
Context parameter basically takes care of runtime details for the Lambda function to execute. We can interact with the Lambda function using the context param. It has the details like the time left before AWS Lambda terminates a functioni.e, timeout specified while creating Lambda function, name of the Lambda function, cloudwatch group name, arn details etc.