Infrastructure as Code (IaC)
Infrastructure as Code (IaC) is a pattern of
provisioningandmanaginginfrastructure through code instead of through manual processes.
By defining infrastructure configurations in code, IaC makes setting up servers, networks, databases, and
other resources repeatable and consistent. This approach enables automation, reduces human error, and
allows teams to version, review, and track infrastructure changes, just like application code. Using IaC,
teams can deploy infrastructure at scale, enforce standards.
Benefits of IaC
1. Consistency and Repeatability
- No Configuration Drift: Ensures environments remain identical across development, testing, and production.
- Standardized Setup: Enables consistent setups for servers, databases, and networks across environments.
- Reliable Recovery: Quickly redeploys infrastructure from code when needed.
2. Efficiency and Automation
- Automated Provisioning: Speeds up resource creation, updates, and deletion.
- Scalable Deployment: Easily deploys infrastructure across multiple regions or environments.
- Reduced Manual Work: Saves time by automating repetitive tasks.
3. Version Control and Traceability
- Change History: Tracks infrastructure changes, enabling a clear record of modifications.
- Rollback Capability: Allows reverting to previous configurations if needed.
- Improved Collaboration: Teams can review, version, and manage infrastructure like application code.
4. Cost Efficiency
- Optimized Resource Usage: Automates scaling of resources to control costs.
- Faster Time-to-Market: Reduces time spent setting up environments manually.
- Minimized Downtime: Ensures smooth, predictable infrastructure changes.
5. Enhanced Security and Compliance
- Standardized Security: Embeds security best practices directly into configurations.
- Auditable Changes: Provides an audit trail for all infrastructure changes.
- Policy Enforcement: Applies security and compliance standards consistently.
IaC Core Concepts
Mutable vs. Immutable Infrastructure
When automating infrastructure with Infrastructure as Code (IaC), one of the key decisions is whether to use mutable or immutable infrastructure.
-
Mutable Infrastructure: This type of infrastructure can be modified or updated after it's first created. Imagine you have a virtual machine running an application in production. If a configuration needs to change—like updating a software package or applying a security patch—you can log in, make the change, and keep the same server running. This flexibility can be helpful for quick fixes or custom adjustments, but it introduces potential issues:
- Configuration Drift: Over time, multiple manual changes can lead to inconsistencies across environments (e.g., development, testing, production).
- Complexity in Tracking Versions: Each change alters the server's state, making it harder to know exactly what’s running on each server or to roll back to a previous version.
-
Immutable Infrastructure: In contrast, immutable infrastructure is fixed once it’s created. If a change is needed, new infrastructure is created with the updated configuration, and the old infrastructure is decommissioned. This approach prevents unexpected changes over time and ensures consistency. ting a new AMI, any instance spun up from that AMI will have exactly the same setup, eliminating the risk of configuration drift.
| Tool | Type | Fits Best With | Key Characteristics |
|---|---|---|---|
| Chef | Configuration Management | Mutable Infrastructure | Uses agents to apply configuration changes directly to running servers |
| Ansible | Configuration Management | Mutable Infrastructure | Agentless, applies changes over SSH, ideal for ad hoc configurations |
| Terraform | Provisioning and Orchestration | Immutable Infrastructure | Manages entire resource lifecycle, often replacing rather than modifying resources |
| Vagrant | Development Environment Automation | Immutable Infrastructure | Automates the creation of virtual machine environments, ideal for local development or testing |
| Packer | Image Creation and Provisioning | Immutable Infrastructure | Creates machine images (VM, Docker, etc.) for consistent, reusable environments |
Aproaches to Infrastructure as Code (IaC)
There are generally two approaches to IaC: declarative (functional) vs. imperative (procedural).
-
Declarative Approach (Functional) – Focuses on "What"
- Describes the end state you want for your infrastructure, and the system automatically makes it happen.
- Example: If you want three servers, you simply declare "I need three web servers." The system takes care of creating or removing servers as needed to meet this target.
- Illustration: Ordering a pizza—you specify the type of pizza you want, and the restaurant handles the details of making it.
-
Imperative Approach (Procedural) – Focuses on "How"
- Specifies each step required to reach the desired state, giving you control over the exact process.
- Example: To set up three servers, you list each step: "create server 1," "create server 2," and so on, ensuring each action happens in order.
- Illustration: Following a recipe—you follow each step in a sequence to achieve the final dish.
| Tool | Declarative | Imperative |
|---|---|---|
| Puppet | ✅ | ❌ |
| Chef | ✅ | ❌ |
| Ansible | ❌ | ✅ |
| SaltStack | ✅ | ✅ |
Infrastructure as Code (IaC) Methods
Infrastructure as Code (IaC) allows you to manage servers and their configurations using code. There are two ways to send these configurations to servers: the 'push' and 'pull' methods. In the 'push' method, the system controlling the configuration directly sends instructions to the server. In the 'pull' method, the server retrieves its own instructions from the controlling system.
| Tool | Master-Based | Masterless | Agent-Based | Agentless |
|---|---|---|---|---|
| Puppet | ✅ | ❌ | ✅ | ❌ |
| Chef | ✅ | ❌ | ✅ | ❌ |
| Ansible | ❌ | ✅ | ❌ | ✅ |
| SaltStack | ✅ | ✅ | ✅ | ✅ |
Infrastructure as Code (IaC) Tool Types
1. Configuration Management Tools
Configuration management tools are a type of IaC tool that focuses on installing and managing software on existing servers. These tools enable the automation of configuration management tasks, making it easier to ensure that all servers in an environment are consistently configured. Examples of Configuration Management Tools include
- Puppet
- Chef
- Ansible
2. Server Templating Tools
Server templating tools are another type of IaC tool. These tools allow for the creation of reusable “templates” that define a server’s configuration. This makes it easy to spin up new servers that are identically configured to a defined standard. Examples of server templating tools include
- Docker
- Vagrant
- Packer
3. Orchestration Tools
Orchestration Tools are IaC tools that manage the interconnections and interactions between different parts of an infrastructure. These tools are crucial for managing complex environments with multiple interconnected components. Examples of orchestration tools include
- Kubernetes
- Docker Swarm
- Red Hat OpenShift
4. Provisioning Tools
Provisioning tools are IaC tools that focus on the initial setup of servers and other infrastructure components. These tools automate the process of provisioning new infrastructure, making it faster and more reliable. Examples of provisioning tools include
- Terraform
- Pulumi
- AWS CloudFormation
- Google Cloud Deployment Manager.
Based on their area of focus on we can categorize IaC tools into four categories.
| Tool Type | Description | Examples |
|---|---|---|
| Configuration Management | Focuses on installing and managing software on existing servers, automating configuration tasks to ensure consistent setup across environments. | Puppet, Chef, Ansible |
| Server Templating | Allows the creation of reusable templates to define server configurations, making it easy to launch new servers with identical configurations. | Docker, Vagrant, Packer |
| Orchestration | Manages interactions and connections between different infrastructure components, essential for complex, interconnected environments. | Kubernetes, Docker Swarm, Red Hat OpenShift |
| Provisioning | Focuses on the initial setup of servers and infrastructure components, automating the provisioning process to make it faster and more reliable. | Terraform, Pulumi, AWS CloudFormation, Google Cloud Deployment Manager |
IaC Tools: Approach, Tool Type, and Method
| Tool | Approach | Tool Type | Method |
|---|---|---|---|
| Terraform | Declarative | Provisioning | Agentless |
| Pulumi | Flexible (Imperative / Declarative) | Provisioning | Agentless |
| AWS CloudFormation | Declarative | Provisioning | Agentless |
| Google Cloud Deployment Manager | Declarative | Provisioning | Agentless |
| Ansible | Declarative | Configuration Management | Agentless |
| Puppet | Declarative | Configuration Management | Agent-Based |
| Chef | Imperative | Configuration Management | Agent-Based |
| Chef Zero | Imperative | Configuration Management | Flexible (Agent or Agentless) |
| SaltStack | Declarative | Configuration Management | Flexible (Agent or Agentless) |
| Docker Compose | Declarative | Templating | Agentless |
| Vagrant | Imperative | Templating | Agentless |
| Packer | Imperative | Templating | Agentless |
| Kubernetes | Declarative | Orchestration | Agentless |