This is a continuation of articles on Infrastructure-as-code aka IaC for short.  There’s no denying that IaC can help to create and manage infrastructure and that they can be versioned, reused and shared – all of which helps to provision resources quickly and consistently and manage them consistently throughout their lifecycle. Unlike software product code that must be general purpose and provide a strong foundation for system architecture and aspiring to be a platform for many use cases, IaC often varies a lot and must be manifested in different combinations depending on environment, purpose and scale and encompass complete development process. It can even include CI/CD platform, DevOps, and testing tools. The DevOps based approach is critical to rapid software development cycles. This makes IaC spread over in a variety of forms. The more articulated the IaC the more predictable and cleaner the deployments.

The IAC architecture is almost always dominated by the choice of technology stacks. There is no universal system architecture but a more devops oriented tailored approach with all the tools necessary to keep the deployments consistent and repeatable. Technology varies with cloud native forms, providers like Ansible, Terraform, and domain specific language such as Pulumi. IaC can be curated as a set of machine-readable files, descriptive model, configuration template, and an imperative approach.  Then there are two approaches for writing it which are an imperative approach and a declarative approach. The imperative approach allows users to specify the exact steps to be taken for a change and the system does not deviate from them while a declarative approach specifies the final form and the tool or platform involved goes through the motion of provisioning them.

Infrastructure can be made available as a service and shared as code.  Provisioning infrastructure can be a cloud service and many public clouds offer it in their service portfolio. These so-called native infrastructures are great for leveraging the public cloud built-in features but more than usual, organizations build a veritable library of assets and prefer it to not be limited to any one cloud-based resources. It can even include on-premises infrastructure. No matter what choices are made and the decision process for navigating the IaC landscape, it is unquestionable that IaC reduces shadow IT within organizations, integrates directly with CI/CD platforms, version controlling infrastructure and configuration changes, standardizing infrastructure, effectively managing configuration drift and with the ability to scale up or out without increasing CapEx or OpEx.

Configuration Management is separate from infrastructure management although tools like Ansible provide hybrid solutions. True configuration management is demonstrated by software like CFEngine while infrastructure management is demonstrated by providers like Terraform and Pulumi. Businesses can mix and match any tool and use them in their CI/CD pipelines depending on their custom requirements.

As a real-world example, a developer writes application code and the configuration management related instructions that will trigger actions from the virtualization environment. When the code is delivered, the configuration management and infrastructure management provide a live operational environment for testing. When the tests run and the error detection and resolution occur, the new code changes become ready for deployment to customer facing environments. Managing the state drift as changes keep propagating is one of the core management routines for Infrastructure-as-code.

#codingexercise

Q: An array A of N elements has each element within the range 0 to N-1. Find the smallest element P such that every value that occurs in A also occurs in sequence A[0], A[1] ... A[P]

For example, A = [2,2,1,0,1] and the smallest value of P is 3 where elements 2,2,1,0 contain all values that occur in A.

A: 

public int getPrefix(int[] A) {

Int prefix = Integer.MIN_VALUE;

Int n = A.length;

Int visited = new int[n];

for (int i = 0; i < n; i++) {

     if (visited[A[I]] == 0){

         visited[A[I]] = 1;

         prefix = I;

     }

}

return prefix;

}