Terraform vs. Ansible : Key Differences and Comparison of Tools

How does Terraform work? | Features of Terraform | How does Ansible work? | Features of Ansible | Difference between Terraform and Ansible Provisioning | Configuration Management vs. Orchestration | Procedural vs Declarative | Terraform vs Ansible Provisioning | Which one to choose: Terraform or Ansible? | Conclusion

Ansible vs Terraform battle continues to escalate as the DevOps environment focuses more on automation and orchestration. These two tools help in automating configurations and deploying infrastructure. Terraform offers to deploy Infrastructure as a Code, helps in readability and lift and shift deployments. Ansible is a configuration management tool for automating system configuration and management.

To explain in short, Terraform is open-source, Infrastructure as Code platform, whereas Ansible is open-source configuration management tool.

What is Terraform?

Terraform is an open-source tool for building, changing, and versioning infrastructure securely and effectively. It is an Infrastructure as a Code tool that is very straightforward to use. It helps to develop and scale Cloud services and manage the state of the network. Its primary use is in data centers and software-defined networking environments. It does not install and manage software on existing devices; instead, it creates, modifies, and destroys servers and various other cloud services. Slack, Uber, Starbucks, Twitch, all big brands are using Terraform. We can also integrate Terraform with Microsoft Azure, Heroku, and Google Compute Engine, etc.

Now, we will discuss the working of terraform.

How does Terraform work?

There are two main working components of terraform.

• Terraform Core
• Providers

Terraform is of declarative nature. It directly describes the end state of the system without defining the steps to reach there. It works at a high level of abstraction to describe what services and resources should be created and defined.

Terraform core takes two input sources to do its job. The first input source is a terraform configuration that is configured by its users. Users define what needs to be provisioned and created. The second input source is a state that holds information about the infrastructure.

So terraform core takes the input and figures out various plans for what steps to follow to get the desired output.

The second principal component is providers, such as cloud providers like AWS, GCP, Azure, or other Infrastructure as service platforms. It helps to create infrastructure on different levels. Let’s take an example where users create an AWS infrastructure, deploy Kubernetes on top of it, and then create services inside the cluster of Kubernetes. Terraform has multiple providers for various technologies; users can access resources from these providers through terraform. This is the basic working terminology of terraform that helps to provision and cover the complete application set up from infrastructure to fully developed application.

Check out: Terraform cheat sheet.

Features of Terraform

As we have discussed the working of Terraform, now we will look at the features of Terraform.

• Terraform follows a declarative approach which makes deployments fast and easy.
• It is a convenient tool to display the resulting model in a graphical form.
• Terraform also manages external service providers such as cloud networks and in-house solutions.
• It is one of the rare tools to offer building infrastructure from scratch, whether public, private or multi-cloud.
• It helps manage parallel environments, making it a good choice for testing, validating bug fixes, and formal acceptance.
• Modular code helps in achieving consistency, reusability, and collaboration.
• Terraform can manage multiple clouds to increase fault tolerance.

Also Check: Our blog post on Terraform Workflow. Click here

What is Ansible?

Ansible is the most significant way to automate and configure apps and IT infrastructure.  Ansible is an open-source configuration management tool mainly designed for provisioning and deploying applications using IaaC.

It has its own language to describe system configuration. Ansible is agentless, making it manage large deployments across enterprises using Windows Power Shell or SSH to perform its tasks. Ansible is not completely declarative; it is a hybrid of procedural and declarative. It can integrate with Amazon EC2, Docker, and Kubernetes. Companies like Zalando, Revolt, and 9gaga are using Ansible.

Let’s see the working of Ansible.

How does Ansible work?

Ansible is agentless and doesn’t run on target nodes. It makes connections using SSH or other authentication methods. It installs various Python modules on the target using JSON. These modules are simple instructions that run on the target. These modules are executed and removed once their job is done. This strategy ensures that there is no misuse of resources on target. Python is mandatory to be installed on both the controlling and the target nodes.

Ansible management node acts as a controlling node that controls the entire execution of the playbook. This node is the place to run the installations. There is an inventory file that provides the host list where the modules need to be run. The management node makes SSH connections to execute the modules on the host machine and installs the product. Modules are removed once they are installed in the system. This is the simple working process of Ansible.

Let’s have a look at the features of ansible.

Features of Ansible

Now we will discuss various features Ansible provides to benefit its users.

• Ansible is used for configuration management and follows a procedural approach.
• Ansible deals with infrastructure platforms such as bare metal, cloud networks, and virtualized devices like hypervisors.
• Ansible follows idempotent behavior that makes it to place node in the same state every time.
• It uses Infrastructure as a Code system configuration across the infrastructure.
• It offers rapid and easy deployment of multi-tier apps with being agentless.
• If the code is interrupted, it allows entering the code again without any conflicts with other invocations.

Check out: Ansible Configuration Management Tools

Similarities between Terraform and Ansible

Given the features of both technologies, Terraform and Ansible appear to be extremely similar tools at a high level. They are both capable of setting up the new cloud infrastructure and equipping it with the necessary application components.

On the freshly formed virtual machine, remote commands can be carried out by both Terraform and Ansible. This indicates that neither tool requires an agent. Agent deployment on the computers is not necessary for operational reasons.

Terraform builds infrastructure utilizing the APIs of cloud providers, and SSH is used for simple configuration operations. The same is true of Ansible; all necessary configuration activities are carried out over SSH. Both tools are masterless since the “state” information for neither requires a separate piece of infrastructure to manage.

Difference between Terraform and Ansible Provisioning

Let’s see how Terraform vs. Ansible battle differentiates from each other:

Also Check: Our blog post on Terraform Create VM. Click here

Orchestration vs. Configuration Management

Terraform and Ansible have so many similarities and differences at the same time. The difference comes when we look at two significant concepts of DevOps: Orchestration and configuration management.

Declarative vs. Procedural

There are two main categories of DevOps tools: Procedural vs. Declarative. These two categories tell the action of tools.

Terraform follows the declarative approach, ensuring that if your defined environment suffers changes, it rectifies those changes. This tool attempts to reach the desired end state described by the sysadmin. Puppet also follows the declarative approach. With terraform, we can describe the desired state and figure out how to move from one state to the next automatically.

Ansible is of hybrid nature. It follows both declarative and procedural style configuration.  It performs ad-hoc commands to implement procedural-style configurations. Please read the documentation of Ansible very carefully to get in-depth knowledge of its behavior. It’s important to know whether you need to add or subtract resources to get the desired result or need to indicate the resources required explicitly.

Mutable vs. Immutable

A workflow for application deployment involves providing the infrastructure, installing the correct version of the source code, and installing any dependencies.

The infrastructure that serves as the foundation for later versions of apps and services has a property known as mutability. Either existing infrastructure is used for deployment, or we can create an entirely new set of infrastructure for it.

It depends on the deployment procedures whether the infrastructure is mutable or immutable. It is said to as malleable when subsequent versions of apps are released on the same infrastructure. However, it is said to as immutable if the deployment takes place during releases on entirely new infrastructure.

Although mutability appears convenient, there is a higher chance of failure. The previous version must first be uninstalled before the desired version can be installed when application configurations are applied again on the same infrastructure. Additional steps increase the likelihood of failure. This can lead to inconsistent setups and unpredictable behavior across a fleet of servers.

Instead, if we concentrate on minimizing these steps by skipping the uninstalling process and carrying out the installation on fresh infrastructure resources, we will have the opportunity to test the new deployment and roll it back in case it doesn’t work. This approach to treating infrastructure as immutable gives administrators more control over making changes.

State Management

The full lifecycle of the resources under Terraform’s administration is managed. It keeps up the state files’ mapping of infrastructure resources to the most recent configuration. State management is crucial to Terraform’s operation.

States are used to monitor configuration changes and provide the same. Additionally, it is possible to import preexisting resources managed by Terraform by bringing in state files from the infrastructure of the real world.

It is possible to query the Terraform state files at any moment to learn about the infrastructure components and their available characteristics.

Ansible, in contrast, does not provide any form of lifecycle management. Any changes made to the configuration are automatically implemented on the target resource because Ansible focuses on configuration management and assumes immutable infrastructure by default.

Also Check: Our blog post on Terraform Tips and Tricks. Click here

Terraform vs Ansible Provisioning

Terraform deals with infrastructure automation. Its current declarative model lacks some features which arise complexity. Using Terraform, the elements of required environments are separately described, including their relationships. It assesses the model, creates a plan based on dependencies, and gives optimized commands to Infrastructure as a Service. If there is no change in the environment or strategy, repeated runs will do nothing. If there is any update in the plan or environment, it will synchronize the cloud infrastructure.

Ansible follows a procedural approach. Various users create playbooks that are evaluated through top to bottom approach and executed in sequence. Playbooks are responsible for the configuration of network devices that contributes towards a procedural approach.  Of course, Ansible provisions the cloud infrastructure as well. But its procedural approach limits it to large infrastructure deployments.

Check Out: Ansible Beginner Tutorial. Click here

Which one to choose: Terraform or Ansible?

Terraform vs. Ansible: Every tool has its unique characteristics and limitations. Let’s check out which one to go with.

Terraform comes with good scheduling capabilities and is very user-friendly. It integrates with docker well, as docker handles the configuration management slightly better than Terraform. But there is no clear evidence of how the target devices are brought to their final state, and sometimes, the final configuration is unnecessary.

Ansible comes with better security and ACL functionality. It is considered a mature tool because it adjusts comfortably with traditional automation frameworks. It offers simple operations and helps to code quickly. But, on the other hand, it is not good at services like logical dependencies, orchestration services, and interconnected applications.

You can now choose between these two, according to the requirement of the situation and the job. For example, if the containerized solution is used to provision software within the cloud, then Terraform is preferable. On the other hand, if you want to gain reasonable control of your devices and find other ways to deploy underlying services, Ansible is more suitable. These tools will provide more comprehensive solutions in the future.

Conclusion

It is essential to know which tool is used for which job among Terraform vs. Ansible. Terraform is mainly known for provisioning infrastructure across various clouds. It supports more than 200 providers and a great tool to manage cloud services below the server. In comparison, Ansible is optimized to perform both provisioning and configuration management. Therefore, we can say that both Terraform and Ansible can work hand in hand as standalone tools or work together but always pick up the right tool as per the job requirement.

References

• Terraform Installation Overview
• Variables in Terraform
• Terraform Providers Overview
• Ansible Documentation 
• Terraform Documentation
• [AZ-400] Azure DevOps Certification Path
• HashiCorp Infrastructure Automation Certification: Terraform Training
• Everything you need to know about Terraform Certification
• [AZ-400] Microsoft Azure DevOps Certification Exam: Everything You Need To Know

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