Developing Serverless Cloud Components

A cloud component contains both your code and the necessary platform configuration to run it. The concept is similar to Docker containers, but here it is applied to serverless applications. Instead of wrapping an entire server in a container, a cloud component tells the cloud platform what services it depends on.

A typical cloud component might include a REST API, a database table and the code needed to implement the related business logic. When you deploy the component, the necessary database services and API services are automatically provisioned in the cloud. Developers can assemble cloud applications from cloud components. This resembles the way they would compose traditional applications from software modules. The benefit is less repeated work to implement the same features in every project over and over again. In the following sections we'll take a look at some new technologies for developing cloud components.

AWS CDK

AWS CDK, short for Cloud Development Kit, is Amazon's new framework for defining AWS cloud infrastructure with code. It currently supports TypeScript, JavaScript and Java with more language support coming later. When developing with AWS CDK, you use code to define both infrastructure and business logic. These codebases are separate. You define your component's deployment logic in one script file, and your Lambda function code in another script file. These files don't have to be written in the same programming language. AWS CDK includes the AWS Construct Library, which provides a selection of predefined cloud components to be used in applications. It covers a large portion of Amazon's AWS cloud services, although not all of them. These predefined constructs are the smallest building blocks available in AWS CDK. For instance, you can use the AWS DynamoDB construct to create a database table. The deployment process translates this construct into a CloudFormation resource, and CloudFormation creates the actual table. The real power of AWS CDK comes from the ability to combine the smaller constructs into larger reusable components. You can define an entire microservice, including all the cloud resources it needs, and use it as a component in a larger application. This modularity can also help standardize multi-team deployments. When everybody delivers their service as an AWS CDK construct, it's straightforward to put all the services together without spending lots of time writing custom deployment scripts. AWS CDK may become very important for cloud application development if third parties start publishing their own Construct Libraries online. There could eventually be very large selection of reusable cloud components available in an easily distributable and deployable format. Right now the framework is still pending a 1.0 release before freezing its APIs.

Serverless Components

Serverless Components is an ambitious new project by the makers of the hugely popular Serverless Framework. It aims to offer a cloud-agnostic way of developing reusable cloud components. These components can be assembled into applications or into higher order components. The basic idea of Serverless Components is similar to AWS CDK. But while CDK uses a programming language to define components, Serverless has chosen a declarative YAML syntax instead. This results in simpler component definitions but you also lose a lot of flexibility. To remedy this, Serverless Components lets you add custom JavaScript files to perform additional deployment operations. The Serverless Components project has its own component registry. The registry includes some basic components for Amazon AWS, Google Cloud, Netlify and GitHub. Unlike in some other projects, developers are writing these components manually instead of auto-generating them from service definitions. It will probably take a while before all cloud features are supported. One controversial design decision of Serverless Components is to bypass the AWS CloudFormation stack management service. The tool creates components directly on AWS and other cloud platforms. It writes their state to a local state.json file, which developers must share. This approach offers speed, flexibility and multi-cloud support, but also requires Serverless Components to handle deployments flawlessly in every situation. Enterprise AWS users will probably be wary of adopting a solution that bypasses CloudFormation entirely.

Pulumi

Pulumi.io is a cloud component startup offering a SaaS service subscription combined with an open source framework. Essentially Pulumi aims to replace AWS CloudFormation and other cloud deployment tools with its own stack management solution. Pulumi's cloud service deploys the actual cloud applications to Amazon AWS, Microsoft Azure, Google Cloud, Kubernetes or OpenStack. Pulumi supports a higher level of abstraction than the other component technologies discussed here. When you implement a serverless service using Pulumi's JavaScript syntax, the code gets translated to a format suitable for the platform you are deploying on. You write your business logic as JavaScript handler functions for Express API endpoints. Pulumi's tool extracts those handlers from the source code and deploys them as AWS Lambda functions, Azure Functions or Google Cloud Functions. Writing completely cloud-agnostic code is challenging even with Pulumi's framework. For certain things it offers cloud-agnostic abstractions like the cloud.Table component. When you use cloud. Table, your code automatically adapts to use either DynamoDB or Azure Table Storage depending on which cloud platform you deploy it on. For many other things you have to write cloud-specific code. Or, you can write your own abstraction layer to complement Pulumi's framework. Such abstraction layers tend to add complexity to applications, making it harder for developers to understand what the code is actually doing. Ultimately it's up to you to decide whether you want to commit to developing everything on top of an abstraction layer which everybody must learn. Also, as with Serverless Components, you can't use AWS CloudFormation to manage your Pulumi-based stacks.

Conclusion

The main issue to consider in choosing a cloud component technology is whether you need multi-cloud support or not. Single-cloud development is arguably more productive and lets developers leverage higher level cloud services. On the other hand this results in increased vendor-lock, which may or may not be a problem. For developers focusing on Amazon AWS, the AWS CDK is a fairly obvious choice. AWS CDK is likely to become a de-facto standard way of packaging AWS-based cloud components. As serverless applications get more and more popular, AWS CDK fills some important blank spots in the CloudFormation deployment process and in the reusability of components. And since AWS CDK still uses CloudFormation under the hood, adopters will be familiar with the underlying technology. Developers that truly require multi-cloud will have to consider whether it's acceptable to rely on Pulumi's third party SaaS service for deployments. If the SaaS service goes down, deployed applications will keep working but you can't update them. This is probably not a big problem for short periods of time. It will be more problematic if Pulumi ever shuts down the service permanently. For projects where this is not an issue, Pulumi may offer a very compelling multi-cloud scenario. Multi-cloud developers that want to contribute to open source may want to check out the Serverless Components project. It's too early to recommend using this project for actual use cases yet, but it may have an interesting future ahead. The project may attract a lot of existing users if the developers are able to provide a clear migration path from Serverless Framework. If you would like more information on how Nordcloud can help you with serverless technologies, contact us here.