AWS 中的 Cloudformation/Serverless 与 Terraform

Question

I would like to understand the need of tools like Terraform. When we do have Cloudformation template available and one can create/update all AWS services with that , What is the point in using a service like Terraform. Please Suggest.

Answer 1

There are a couple of reasons why you might choose Terraform over CloudFormation:

1. Vendor Agnostic: There might be a point in the future where you need to migrate your cloud infrastructure. This could be due to several reasons (eg costs, regulatory compliance, etc.). With Terraform you are still able to use the same tool to deploy the new infrastructure. With smart use of Terraform modules you can even leave large parts of your infrastucture as code repository in tact.
2. Support for other tools: This also builds a bit on the previous point, but Terraform can deploy a lot more then just AWS resources. For example, you can use Terraform to orchestrate the deployment of an EC2 machine that is then configured with Ansible. Or you could use Terraform to deploy applications on top of your Kubernetes cluster. While CloudFormation supports custom resources via the creation of custom Lambdas, it is quite a lot of work to maintain.
3. Wider ecosystem: Due to the Open Source nature of Terraform, there is a huge ecosystem of tools that help you solve all kinds of issues, such as testing the infrastructure as code or building in compliance in a continuous fashion.
4. Arguably a better language: Personally I think Terraform is a way more suited for Infrastructure as Code then CloudFormation. Terraform has a lot more flexibility build in to the language (HCL) and their module system allows for a lot more composability then what can be achieved in CloudFormation.

Answer 2

CloudFormation (CFN) and Terraform (CF) are both Infrastructure as Code (IaC) development tools.

However, CFN is only for AWS . You can't use it with Azure, GCP or anything else outside of AWS ecosystem. In contrast, TF is cloud agnostic . You can use it across not only multiple cloud providers, but also to work with non-cloud products, such as docker, various databases and even domino pizza if you want.

So the main advantage of TF is that once you learn it only once , you can apply it to a number of cloud providers. CFN is only useful in AWS, and once you stop using CFN, you have to learn something new to work with other cloud.

There are also difference in how TF and CFN work. Both have their strengths and weekends . For example:

• when you deploy using CFN all resources are available to view in one central location in AWS along with template's source code. Whereas with TF there is no such place. If you login to the AWS console, you have no idea what was created by TF, what was the source code used, etc.

• TF has loops and complex data structures and condtions, while CFN does not.

• CFN has creation policies and update policies, TF has not.

• You can control access to CFN using CFN policies and IAM policies. You can't do same with TF as it "lives" outside of AWS.