January is the period where you have good resolutions, it's also the time to review the past year. In this article, Dhaval Nagar goes through major complaints about Lambda and lists the evolution the service had in 2020 to address those complaints.
Looking at 2020, you can also check the ICYMI Q4 2020 blog post, where you will find all news, articles,... and content published by AWS in Q4.

During re:Invent, some code from the Lambda Java runtime has been open sourced. This code permits (among other things) to correctly deserialize json events in java objects. With that, I decided to create a library to ease the tests of java lambda handlers: aws-lambda-java-tests. Finally I wrote this blog post to announce it. If you develop your lambda functions in Java, please give a try and tell me if that's useful!

I'd rather recommend using SAM or Serverless framework to deploy your lambda functions but this set of tutorials is really good. And it's not just about Lambda, but also layers, and using different services (S3, Kinesis, DynamoDB, SQS, API Gateway).
And if you persist in wanting to use Terraform for Lambda functions, read this blog post ("Hard Lessons From Deploying Lambda Functions With Terraform"). It provides some interesting tips, in particular how to build the zip file with dependencies or setting log retention period in Cloudwatch...
And if you already used Terraform and want to try Serverless framework, check this post ("AWS Serverless Provisioning: Terraform + Serverless Framework") as it could be helpful if you want to share some resources between the two worlds.

Great article from Aidan Steele, explaining why you should not use the $LATEST version of a Lambda function. Instead, you should create new versions each time you deploy an update (straightforward with SAM). And you should use aliases to facilitate references to your function (with API Gateway for example).

Really complete article from Miron Machnicki, based on his experience from the last year. It covers a lot of topics and is a must read to avoid some pitfalls and get some great advice. It's also a good way to start your journey to serverless (note that it's not a tutorial).

Sheen Brisals, from LEGO, is used to provide great articles and this one is no exception to the rule. Cost is often an important driver for companies to move to the cloud, and even more to serverless. But is it still the main factor? Ease, speed, agility, simplicity are today more important than ever to respond to the market...

Despite the second example of this article where I'm not totally convinced, this article from Guillaume Lannebere gives a lot of information about API Gateway (provisioning, security, throttling, REST vs HTTP, ...). In particular, it explains how to use it as a proxy for private resources inside your VPC.

Talking about API, and if you are in the Azure world, I don't forget you, here is a series of 5 articles to dive deep in Azure API Management and Azure Logic Apps: How to integrate them (part 1), secure the Logic App with IP filtering (part 2), have one API in front of several Logic Apps (part 3), API documentation (part 4), and tags and headers (part 5). Lots of useful details!

In this article, Chameera Dulanga gives several tips to improve your serverless applications performance: use provisioned concurrency to avoid cold start, use RDS Proxy to avoid overwhelming your relational database, use the appropriate amount of memory... Regarding this last point, AWS released a new feature in the Compute Optimizer that now provides advice to improve performance & costs of your functions. And if you are using containers to package your lamda, Rob Sutter also provides meaningful information to optimize lambda functions packaged that way.

Well, if you read this newsletter every two weeks, there are chances that you know a bit about serverless. But it is also possible that you want to improve your skills. Then this article may help, as it provides a list of courses you can follow to become a serverless expert. However, I think one important is missing: theburningmonka (Yan Cui).