Thread by @alexxubyte

𝐒𝐞𝐫𝐯𝐞𝐫𝐥𝐞𝐬𝐬 is one of the hottest topics in cloud services. How does AWS 𝐋𝐚𝐦𝐛𝐝𝐚 work behind the scenes?

Lambda is a 𝐬𝐞𝐫𝐯𝐞𝐫𝐥𝐞𝐬𝐬 computing service provided by Amazon Web Services (AWS), which runs functions in response to events.

𝐅𝐢𝐫𝐞𝐜𝐫𝐚𝐜𝐤𝐞𝐫 𝐌𝐢𝐜𝐫𝐨𝐕𝐌
Firecracker is the engine powering all of the Lambda functions [1]. It is a virtualization technology developed at Amazon and written in Rust.

The diagram below illustrates the isolation model for AWS Lambda Workers.

Lambda functions run within a sandbox, which provides a minimal Linux userland, some common libraries and utilities. It creates the Execution environment (worker) on EC2 instances.

How are lambdas initiated and invoked? There are two ways.

𝐒𝐲𝐧𝐜𝐡𝐫𝐨𝐧𝐨𝐮𝐬 𝐞𝐱𝐞𝐜𝐮𝐭𝐢𝐨𝐧
Step1: "The Worker Manager communicates with a Placement Service which is responsible to place a workload on a location for the given host (it’s provisioning the sandbox) and returns that to the Worker Manager" [2].

Step 2: "The Worker Manager can then call 𝘐𝘯𝘪𝘵 to initialize the function for execution by downloading the Lambda package from S3 and setting up the Lambda runtime" [2]

Step 3: The Frontend Worker is now able to call 𝘐𝘯𝘷𝘰𝘬𝘦 [2].

𝐀𝐬𝐲𝐧𝐜𝐡𝐫𝐨𝐧𝐨𝐮𝐬 𝐞𝐱𝐞𝐜𝐮𝐭𝐢𝐨𝐧
Step 1: The Application Load Balancer forwards the invocation to an available Frontend which places the event onto an internal queue(SQS).

Step 2: There is "a set of pollers assigned to this internal queue which are responsible for polling it and moving the event onto a Frontend synchronously. After it’s been placed onto the Frontend it follows the synchronous invocation call pattern which we covered earlier" [2].

Question: Can you think of any use cases for AWS Lambda?

Sources:
[1] AWS Lambda whitepaper: docs.aws.amazon.com/whitepapers/la…
[2] Behind the scenes, Lambda: bschaatsbergen.com/behind-the-sce…
Image source: [1] [2]