In our current IT landscape, structuring, configuring, and provisioning infrastructure is becoming more important than ever. Infrastructure as Code (IaC) has addressed concerns around the ease of automation. An IaC automation tool uses the configuration code as its input and builds the infrastructure based on your specifications.
Infrastructure as Code (IaC)
Infrastructure as Code can be described as the management and deployment of infrastructure using version-controlled code. Your predefined environment specifications through configuration or definition files provide consistent and reliable infrastructure deployments. Automating infrastructure deployment through code ensures that you would not have to manually handle any infrastructure components during each deployment cycle.
In IaC, you have to write the desired parameters in the code and check-in that code into the source repository. Any changes pertaining to the deployment or configuration need to be made in that code itself. Using that code an IaC tool will proceed with the infrastructure provisioning to give you the desired results.
IaC is particularly helpful when prod-like environments need to be deployed quickly and accurately on an on-demand basis. You will also have the flexibility of making your infrastructure scalable by predefining your desired state in the code itself. This will provide you with deployment consistency and help avoid any runtime problems due to absent dependencies or configuration drift.
While providing instructions in your code to deploy the infrastructure, you can use either of two approaches – imperative and declarative.
Imperative vs Declarative
In an imperative infrastructure approach, you can define every execution step leading to your desired state of infrastructure. This gives you complete control over the automated deployment process where you can define the configurations and sequence of every stage, restricting the system to stray from your defined steps. This is quite useful for complex environments that need precise parameters.
Whereas in a declarative infrastructure approach, you will just have to define your desired requirement, and the automation platform/tool will take care of the rest. One of the key benefits of the declarative approach is that you would not need to have an in-depth knowledge of every step and configuration. A declarative IaC will also provide you with better idempotence which means that multiple executions will produce the same result each time. Since all you define is the final desired state, you will have the same result regardless of your method. Most organizations opt for a declarative approach because of its convenience and flexibility.
Some other benefits of declarative infrastructure include:
- Version control
- Defining desired final state
- Convenient to manage configuration drifts
- Easier repeatability
- Centralized resource management
- Centralized security management
- Deployment transparency
Suppose you need to deploy an application through the declarative approach, you will need to define the application version and its post-installation configuration in the definition file. The declarative IaC tool will figure out the process of installing the application and how to configure it. This would save you time, and effort and unlike in an imperative approach, you can avoid diving deep into the steps involved for the deployment.
Declarative Infrastructure is a key part of the GitOps deployment methodology. The main concept of GitOps is to reconcile the desired state and the current state. Hence, GitOps consists of a Git repository with declarative infrastructure descriptions, that are supposed to result in the final desired state of the deployed infrastructure. Like in the case of Kubernetes in GitOps (which in itself is a declarative system), to provide access to Kubernetes services from outside the Kubernetes cluster, a declarative, cloud-native ingress is necessary. This declarative approach allows Kubernetes to offer automated, streamlined and scalable applications.
The IaC tool in GitOps handles the deployment activity with automation. Software or drift agents will alert you in case of any deviation from the desired state in the current production environment. This will ensure compliance and thereby also help you with Compliance as Code implementation. You would be able to roll back your environment to a previous state through the version control of declarative infrastructure in GitOps. Declarative infrastructure also contributes to the overall security by providing enhanced stability and optimized expenditure.
Using a declarative infrastructure approach you can also codify your policy-based security in the form of Policy as Code (PaC). Security policies like authentication and authorization protocols, access privileges, delegation policies, and so on, can be configured by using a declarative method. Through this, you will be able to ensure development guardrails and testability of the code. Due to the version control, any manual errors during the security policy implementation can also be avoided. Another benefit you would have is by implementing declarative policy-based security in the IaC, you can get rid of any ambiguous and redundant policies that may exist.
Based on your requirements and approach you can choose from multiple IaC tools. Like you can go for Chef if you prefer an imperative approach. If you want to implement a declarative infrastructure you can use Flux & Flagger, Terraform, Puppet, or Cloudformation. Tools like SaltStack and Ansible are a mix of both worlds but are predominantly declarative in nature.
The extensive use of Terraform, Puppet, and Ansible in the global market makes it quite evident how efficient and reliable declarative infrastructure is. Just by defining the specifications for your infrastructure, you will be able to deploy your environments using the IaC automation tools. This will definitely improve the stability and productivity of your deployment pipeline.
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