Infrastructure as Code Concepts

Infrastructure as Code (IaC) is the practice of provisioning and managing infrastructure resources using code. It is an integral component of DevOps methodology, facilitating the seamless orchestration of applications and their underlying infrastructure such as servers, virtual machines (VMs), databases, and networks.

1 Project Structure and Organization
- 1.1 Directory Structure
- 1.2 Naming Conventions
- 1.3 Repository Layout
  - 1.3.1 Branches
  - 1.3.2 Folder
  - 1.3.3 Versioning
2 Setting Up IaC Environment
- 2.1 Pre-requisite Requirements
- 2.2 Installation and Configuration
- 2.3 Environment Variables
3 Infrastructure Provisioning
- 3.1 Creating Infrastructure Resources
- 3.2 Resource Dependencies and Order
4 Configuration Management
- 4.1 Managing Configuration Files
- 4.2 Parameterization and Variables
- 4.3 Secrets Management

Project Structure and Organization

When handling projects, it's important to establish a well-organized directory structure to effectively manage your project and potential complexities. It's recommended to maintain distinct directories for various purposes and ensure a uniform format, style, and code structure.

Directory Structure

The recommended directory structure for any IaC project includes separating code, configuration, and documentation into organized folders. By following an organized directory structure, you make it easier for team members to locate and manage specific elements of your IaC project, maintain consistency, and collaborate effectively. It also facilitates version control and ensures that your project remains clear, maintainable, and scalable.

Root Directory: The root directory of your IaC project typically contains high-level configuration files and important project-wide documentation. It may include files like "main.tf" (for Terraform) or "site.yml" (for Ansible) as the entry point for your IaC code.
Code Directory: This is where you store the actual IaC code. You should create subdirectories for different components or environments.

For example, you may have subdirectories like "networking," "servers," or "dev," "staging," and "production" if you're managing different environments.

Configuration Directory: This directory is meant for configuration files that are separate from the IaC code. These can include environment-specific configurations, application settings, or any other data that needs to be kept separate from the code logic.

Store configuration files that are separate from your IaC code in this directory.

Documentation Directory: It's a good practice to have a dedicated folder for documentation. This directory should contain files explaining the project's purpose, architecture, and usage, along with any user or developer guides.
Modules/Scripts Directory: If your IaC project is sufficiently complex, you may want to have a directory specifically for reusable modules, scripts, or functions. These can be shared and included in your code as needed.
Variables Directory: Store variable definitions in a dedicated directory. This can help keep variables separate from the code logic and make it easier to manage and change configurations.
Tests Directory: If your IaC project includes automated tests (highly recommended), place your test files or scripts in this directory. This helps ensure code reliability.
Infrastructure State Directory: Some IaC tools maintain state files that track the current state of deployed resources. Keep these files in a separate directory to prevent accidental modifications.
Secrets Directory (Optional): For security and separation of concerns, you may consider having a separate directory for managing secrets and sensitive data. Ensure strict access controls on this folder.
Logs and Reports Directory (Optional): If your IaC project generates logs or reports, you can have a directory for storing these files.
Bin or Scripts Directory (Optional): If you have utility scripts or binaries that assist in the IaC process, place them in this directory.

Note: An IaC project typically undergoes multiple iterations to align with a company's specific project requirements, and its initial definition may not be entirely accurate.

Naming Conventions

Establishing clear and consistent naming conventions for resources, files, and directories within your IaC project is crucial for enhancing project maintainability.

Here are some key considerations:

Resource Naming Conventions: Resources like servers, databases, and networking components should have names that reflect their purpose and attributes.

For example, use meaningful names like “web-server” or “database-prod” to make the resource context more evident.

File Naming Conventions: Maintain a consistent approach to naming your IaC files.

For example, if you’re using Terraform, use a prefix like “main.tf” for your primary configuration file, and then use descriptive file names for additional modules or configurations, such as “networking.tf” or “security-groups.tf”.

Consistency Across Environments: Maintain consistency in naming across different environments (e.g., development, staging, production) to avoid confusion.

For example, if you use “app-server-dev”, use “app-server-staging” and “app-server-prod” for similar resources in other environments.

Version Control Branch and Tag Naming: When managing your IaC project in version control (e.g., Git), consider naming branches and tags with descriptive names that indicate the purpose of a branch or release version.

For example, use “feature/add-ssl” or “v1.2-release”.

Use of Hyphens or Underscores: Choose either hyphens or underscores for separating words in names. Stick with one style throughout your project for consistency.

For example, either only use hyphens as in “web-server” or underscores as in “web_server”.

Avoid Special Characters and Spaces: Steer clear of special characters, spaces, and other non-alphanumeric characters in names, as they can lead to compatibility issues or confusion.

Repository Layout

Organizing your IaC code within your version control repository is essential for maintaining an efficient version control repository for your IaC project, making collaboration, version management, and project tracking smoother and more effective.

Here's a guide on how your IaC code should be structured within a version control repository, including best practices for branches and folders:

Branches

Master/Main Branch: The primary branch (often named "master" or "main") should contain the production-ready code. It should be stable and protected, allowing only approved changes to be merged into it.
Feature Branches: For each new feature, enhancement, or bug fix, create a dedicated feature branch. Use clear and descriptive names, such as "feature/add-load-balancer" or "bugfix/fix-database-connection."
Environment-Specific Branches: Maintain branches for different environments, such as "staging" or "development." These branches can be used for environment-specific configurations.
Release Branches: When preparing for a new release, create a release branch (e.g., "release/v1.0"). Only bug fixes and essential changes should be merged into release branches.
Hotfix Branches: For critical issues in production, create hotfix branches (e.g., "hotfix/ssl-certificate-expiry") to address and deploy immediate fixes.

Folder

Code Folder: Organize your IaC code within a dedicated folder to keep it separate from other project assets.
Modules Folder: If you use reusable modules, create a "modules" folder to store them.
Variables Folder: Keep variable definitions in a "variables" folder for clarity.
Tests Folder: Store your test files or scripts in a "tests" folder to ensure that your code is thoroughly tested.
Documentation Folder: Include a folder for documentation. This is where you can store architecture diagrams, user guides, and other project documentation.

Note: Unlike a directory, which can store files, subdirectories, and other directories, a folder can only store files.

Versioning

Semantic Versioning: Adhere to semantic versioning principles for your IaC code to clearly communicate the impact of changes. Versions typically follow the format “X.Y.Z”, where:
- X is a major version
- Y is a minor version
- Z is a patch version
Tags for Releases: Tag releases with version numbers (e.g., "v1.0.0") to make it easy to reference specific releases in the future.
Commit Messages: Write informative and concise commit messages. Describe the purpose of the change, its impact, and any relevant details. Follow a consistent style guide for commit messages.
Pull Request Reviews: Require code reviews for all pull requests. This ensures that changes are thoroughly examined and conform to project standards.

Setting Up IaC Environment

Establishing a well-configured infrastructure as Code (IaC) environment is the foundational step toward leveraging the full potential of IaC practices.

Pre-requisite Requirements

It’s important to ensure your environment meets certain prerequisites which often include:

Version Control System: Set up a version control system (VCS) to manage your IaC code. The VCS (e.g., Git) will be used for collaboration, versioning, and tracking changes.
IaC Tool: Choose and install an IaC tool that aligns with your infrastructure needs. Popular choices include Terraform and Ansible. Make sure the tool is installed and configured properly.
Cloud or Infrastructure Platform Access: Ensure you have access to your chosen cloud or infrastructure platform. This includes account credentials, access keys, and permissions to provision resources.
Development Environment: Set up a development environment where you will write, test, and maintain your IaC code. This environment may include a code editor, integrated development environment (IDE), or code repositories.
Dependencies and Libraries: Install any required dependencies and libraries related to your IaC tool. This may include specific plugins, extensions, or modules necessary for your project.
Access to Secret Management Tools: If your project involves handling sensitive information, ensure access to secret management tools or mechanisms to securely store and retrieve secrets.

Installation and Configuration

Once you’ve satisfied the pre-requisite requirements, proceed with the installation and configuration of your IaC environment. This typically includes the following steps:

Install IaC Tool: Depending on the tool you’re using, follow the installation instructions provided by the vendor.
- See Terraform Installation Guide for instructions on how to install Terraform.
- See Ansible Installation Guide for instructions on how to install Ansible.
Configure and Authenticate IaC Tool: Configure your IaC tool to authenticate with your cloud provider or infrastructure platform. This involves setting up access keys, authentication tokens, or certificates as required.
Initialize IaC Project: Initialize a new IaC project or work with an existing one by running commands like terraform init or ansible-galaxy init to prepare the project's structure and download necessary modules or dependencies.
Set Up Version Control: Initialize a Git repository for your IaC project and connect it to your version control system. Use Git to track changes, collaborate with team members, and manage version history.

Environment Variables

IaC tools often rely on environment variables for configuration.

Here’s a brief overview of common variables:

AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY: For AWS-based IaC, these variables provide access to AWS services. See Environment variables to configure the AWS for CLI for more information.
TF_VAR_name: Terraform allows you to set variables using the TF_VAR_name prefix. For example, "TF_VAR_db_password" sets the "db_password" variable. See Terraform Environment Variables for more information.
ANSIBLE_VAULT_PASSWORD_FILE: Used with Ansible for decrypting vault-encrypted files. See Ansible Environment Variables for more information.
Other Tool-specific Variables: Depending on the IaC tool you use, additional tool-specific environment variables may be required. Refer to the tool's documentation for guidance.

Infrastructure Provisioning

Infrastructure Provisioning is a fundamental aspect of IaC where the defined infrastructure is created, deployed, and managed as code. Rather than relying on manual and error-prone processes, IaC empowers teams to automate infrastructure provisioning through code, ensuring a highly systematic and repeatable approach.

By embracing Infrastructure Provisioning as a core tenet of IaC, organizations can unlock the advantages of agility, cost-efficiency, and reliability in managing their digital infrastructure. This approach transforms infrastructure management from a manual, error-prone process into a streamlined, automated, and agile practice, aligning it with the principles and practices that have revolutionized software development.

Creating Infrastructure Resources

The core of infrastructure provisioning is defining the resources you need for your project, such as VMs, databases, networks, and more. In your IaC code, you describe the desired state of these resources, specifying their attributes, relationships, and configurations.

We leverage Terraform scripts for cloud resource provisioning at IT-Conductor. Specifically, we've crafted a VM-centric Terraform script, which not only provisions virtual machines but also handles the generation and utilization of necessary resources for these VMs. This versatile script has the ability to connect already existing resources like networks, subnets, keys, and security groups or generate them on the fly for provisioning the VM.

The script accepts a JSON configuration file that houses resource information as its input. Below is an example of a simple configuration file designed for provisioning an Azure VM.

{
  "infrastructure": {
    "region": "westus",
    "resource_group": { 
      "is_existing": "false",
      "name": "itc-rg"
    },
    "vnets": {
      "management": {
        "is_existing": "true",
        "arm_id":"/subscriptions/XXXXXXXXXXXX/resourceGroups/XXXXXXXXX/providers/Microsoft.Network/virtualNetworks/XXXXXXX",
        "address_space": "10.200.0.0/16",
        "subnet_mgmt": {
          "is_existing": "false",
          "name": "single-vm-test-subnet",
          "prefix": "10.200.10.0/24",
          "nsg": {
            "is_existing": "false",
            "name": "nsg-mgmt-single-vm-test",
            "allowed_ips": [
              "0.0.0.0/0"
            ]
          }
        }
      }
    }
  },
  "vms": [
    {
      "name": "vm1",
      "os": {
        "publisher": "suse",
        "offer": "sles-sap-12-sp5",
        "sku": "gen1"
      },
      "size": "STANDARD_B1s",
      "disk_type": "StandardSSD_LRS",
      "authentication": {
        "type": "key",
        "username": "itcuser"
      }
    }
  ],
  "sshkey": {
    "path_to_public_key": "~/.ssh/id_rsa.pub",
    "path_to_private_key": "~/.ssh/id_rsa"
  }
}

In the configuration file, all the fields are self-explanatory. The field is_existing signifies that the resource already exists. If this value is true, it is used by the script to connect to the VM being provisioned. Otherwise, this resource also gets created from the script itself. Also, the keys are stored in ITC as data files and downloaded to the IT-Conductor Gateway temporarily during the provisioning of the VM.

Explore the following scenarios illustrating resource provisioning during migrations:

Resource Dependencies and Order

Some IaC tools handle resource dependency management intelligently, deploying resources in a way that adheres to the dependencies and relationships among defined resources. Familiarize yourself with your chosen tool's behavior in this regard.

In Terraform, you can utilize depends_onand count parameters to control the creation order. This meta-argument handles hidden resource or module dependencies that Terraform cannot automatically infer.

Note: You only need to explicitly declare a dependency when a resource or module relies on the behavior of another resource without utilizing any data from that resource in its parameters.

In Ansible, you can structure your playbooks to execute tasks in the desired sequence. By structuring your playbooks effectively, you can enforce a logical order of operations, execute configurations, and maintain the overall flow of your automation, ensuring that your infrastructure and applications are configured, deployed, and managed in a well-defined and organized manner.

Configuration Management

Configuration management is a pivotal aspect of Infrastructure as Code (IaC) that ensures your infrastructure is consistently configured and maintained to meet your desired state.

Managing Configuration Files

In IaC, configuration management involves the systematic handling of configuration files, which are vital in specifying how your infrastructure components should be set up. These configuration files typically define parameters, settings, and options for resources.

Version Control: Configuration files should be stored in version control systems. This not only provides a historical record of changes but also enables you to roll back to previous configurations if issues arise.
Template Usage: Many IaC tools support template engines to dynamically generate configuration files. This allows for the reuse of configuration blocks and simplifies the management of large-scale infrastructure.
Parameterization: Configuration files often incorporate variables, allowing you to customize settings for different environments or scenarios. Parameters can be defined and managed within your IaC code.

Parameterization and Variables

Parameterization is a key feature of configuration management in IaC. It allows you to customize configurations for different environments or deployments without modifying the core code. Variable usage and management are fundamental to this process, enabling you to:

Define Variables: Create variables within your IaC code to represent dynamic values such as instance counts, IP addresses, or endpoint URLs.
Utilize Variables in Configuration Files: Incorporate variables into your configuration files, allowing you to parameterize settings and achieve flexibility.
Centralize Variable Management: Consider centralizing the management of variables to maintain consistency across your infrastructure and ease the process of making global changes.

Secrets Management

Handling sensitive information securely within your Infrastructure as Code (IaC) code is crucial to maintaining the integrity and security of your infrastructure.

Here are some best practices to follow:

Do Not Hard-code Secrets: Avoid hard-coding sensitive information, such as passwords or API keys, directly into your IaC code. Hard-coded secrets are a significant security risk, as they are easily visible in your code.
Store Secrets in Environment Variables: Store sensitive data as environment variables or secret store references. IaC tools usually provide a way to fetch secrets securely from environment variables or secret stores during runtime.
Rotate Secrets Regularly: Implement a secret rotation policy, ensuring that passwords and keys are periodically updated. This minimizes the risk associated with long-lived secrets.
Implement Access Controls: Set strict access controls on who can read and modify secrets. Limit access to only those who need the secrets for their tasks.
Encrypt Sensitive Data: Encrypt secrets when storing them in your version control system. Use encryption mechanisms to protect sensitive files before committing them.
Use Secret Management Tools: Leverage secret management tools such as HashiCorp Vault, AWS Secrets Manager, or dedicated secret management modules in your IaC tool to securely store and access sensitive data. These tools offer encryption, access controls, and rotation policies.