You can become a serverless blackbelt. Enrol to my 4-week online workshop Production-Ready Serverless and gain hands-on experience building something from scratch using serverless technologies. At the end of the workshop, you should have a broader view of the challenges you will face as your serverless architecture matures and expands. You should also have a firm grasp on when serverless is a good fit for your system as well as common pitfalls you need to avoid. Sign up now and get 15% discount with the code yanprs15!
Update 01/10/2019: a few of you have mentioned layers in the comments or on social media. Scroll to the bottom to see my thoughts on layers as a solution to the problems I mentioned in this post.
A version of the AWS SDK is always bundled into the Lambda runtime for your language. So the conventional wisdom says you don’t need to include it in your deployment artefact.
I’m here to tell you otherwise.
But first, let’s examine the argument for not packing the AWS SDK.
Deployment artefacts are smaller
This means deployment is faster. Although the bulk of the deployment time is with CloudFormation, not uploading the artefact. So the actual time saving depends on your internet speed.
It also means you are less likely to hit the 75GB code storage limit. Which is fair, but I feel this risk can be mitigated with the lambda-janitor.
Lastly, you can actually see and edit your code in the Cloud9 editor! Alright, this is pretty useful when you just wanna quickly check something out. Although when you’re building a production service, you wouldn’t want to rely on the AWS console, ever. You certainly wouldn’t be making code changes directly in the console!
So what’s wrong with relying on the built-in version of the AWS SDK?
The version of the built-in AWS SDK is often much older than the latest. Which means it doesn’t have the latest security patches, bug fixes as well as support for new features. Known vulnerabilities can exist in both the AWS SDK itself as well as its transient dependencies.
This can also manifest itself in subtle differences in the behaviour or performance of your application. Or as bugs that you can’t replicate when you invoke the function locally. Both are problems that are difficult to track down.
If you rely on tests that execute the Lambda code locally then the fact the runtime has a different version of AWS SDK would invalidate your tests. Personally, I think you should always have end-to-end tests as well. Which runs against the deployed system and checks everything works as expected when running inside AWS.
No immutable infrastructure
AWS can update the version of the built-in AWS SDK without notice. This can introduce subtle differences to your application’s behaviour without any action from you.
A while back, AWS updated the version of boto in the Python runtime. Unfortunately, the version they upgraded to had a bug. It caused many people’s functions to suddenly break. This affected Bustle amongst others and many hours were wasted on debugging the issue. As you can imagine, it wasn’t the easiest problem to track down!
In summary, my arguments against using the built-in AWS SDK are:
- The built-in AWS SDK is often out-dated and missing security patches and bug fixes.
- It invalidates integration tests since the runtime uses a different version of the AWS SDK to what was tested.
- AWS can update the built-in AWS SDK without notice
Ultimately, I think the tradeoff is between convenience and safety. And I for one, am happy to sacrifice small conveniences for immutable infrastructure.
What about layers?
Quite a few of you have mentioned Lambda layers as a solution. Yes, you can ship the AWS SDK via layers instead. It would address point 1 and 3 above, but it introduces other challenges. I discussed those challenges in this post, so please give that a read.
Granted, some of those challenges have been tackled – e.g. the Serverless framework now supports layers when you invoke functions locally, and you can introduce semantic versioning to layers by wrapping them in SAR apps. However, it still remains a tooling problem if you want to run unit or integration tests before deploying your functions to AWS. In both cases, you’d still need a copy of the AWS SDK locally. For a dependency that is relatively small (a few MBs) and should be updated frequently, such as the AWS SDK, I don’t feel layers is worth the hassle it brings.
p.s. AWS also recommends including your own copy of the AWS SDK in the official documentation.
Hi, I’m Yan. I’m an AWS Serverless Hero and I help companies go faster for less by adopting serverless technologies successfully.
Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.
Skill up your serverless game with this hands-on workshop.
My 4-week Production-Ready Serverless online workshop is back!
This course takes you through building a production-ready serverless web application from testing, deployment, security, all the way through to observability. The motivation for this course is to give you hands-on experience building something with serverless technologies while giving you a broader view of the challenges you will face as the architecture matures and expands.
We will start at the basics and give you a firm introduction to Lambda and all the relevant concepts and service features (including the latest announcements in 2020). And then gradually ramping up and cover a wide array of topics such as API security, testing strategies, CI/CD, secret management, and operational best practices for monitoring and troubleshooting.
If you enrol now you can also get 15% OFF with the promo code “yanprs15”.
Check out my new podcast Real-World Serverless where I talk with engineers who are building amazing things with serverless technologies and discuss the real-world use cases and challenges they face. If you’re interested in what people are actually doing with serverless and what it’s really like to be working with serverless day-to-day, then this is the podcast for you.
Check out my new course, Learn you some Lambda best practice for great good! In this course, you will learn best practices for working with AWS Lambda in terms of performance, cost, security, scalability, resilience and observability. We will also cover latest features from re:Invent 2019 such as Provisioned Concurrency and Lambda Destinations. Enrol now and start learning!
Check out my video course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. There is something for everyone from beginners to more advanced users looking for design patterns and best practices. Enrol now and start learning!
Here is a complete list of all my posts on serverless and AWS Lambda. In the meantime, here are a few of my most popular blog posts.
- All you need to know about caching for serverless applications
- Lambda optimization tip – enable HTTP keep-alive
- You are wrong about serverless and vendor lock-in
- You are thinking about serverless costs all wrong
- Just how expensive is the full AWS SDK?
- Check-list for going live with API Gateway and Lambda
- How to choose the right API Gateway auth method
- CloudFormation protip: use !Sub instead of !Join
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- Guys, we’re doing pagination wrong
- Top 10 Serverless framework best practices
- How to break the “senior engineer” career ceiling
- My advice to junior developers