How to migrate your existing cloud estate to IaC without breaking anything

Why migrate to Infrastructure as Code (IaC)?

Migrating to Infrastructure as Code (IaC) is a game-changer for businesses looking to improve automation, security, and scalability. However, transforming a traditionally managed cloud estate into one managed by IaC is a significant undertaking, particularly in complex environments.While some aspects of your cloud infrastructure may already be automated, implementing IaC requires careful planning and a phased approach to ensure that the transition is smooth, secure, and scalable. Get it right, and you'll streamline deployments, reduce human error, and optimise costs. Get it wrong, and you risk downtime, misconfigurations, and compliance issues.

Step 1: Assess and document your existing cloud infrastructure

Before deploying Infrastructure as Code, you need a complete, well-documented inventory of your cloud resources. Many organisations lack up-to-date documentation, but this step is critical.

Best practices for cloud assessment:

• Use cloud-native tools like AWS Config, Azure Resource Graph, orGoogle Cloud Asset Inventory to map existing resources.
• Identify dependencies between cloud services to prevent breaking critical connections.
• Create a detailed inventory of infrastructure components, security configurations, and policies.

Why is this important? 

Understanding your cloud architecture is crucial for ensuring IaC consistency during migration, as it helps you avoid issues such as misconfigurations and overlooked dependencies. For example, if you don't have a clear inventory of your cloud assets and their interdependencies, you might inadvertently deploy infrastructure in the wrong order or fail to account for critical service dependencies.

Inconsistencies in IaC can manifest in several ways:

• Misconfigured resources: Without a complete understanding of your current environment, an IaC deployment might accidentally create duplicate resources or misconfigure networking rules, leading to connectivity issues between services.
• Unintended downtime: If the dependencies between services aren’t properly documented, one service might be migrated before another that it relies on, leading to broken services or unnecessary downtime.
• Security gaps: Failing to document all security configurations could result in some resources not being properly locked down, leaving them exposed to unnecessary risks.

For example, imagine you’re migrating a legacy cloud estate where an app relies on a specific network configuration. If you don’t fully document that dependency, your IaC script might miss that network setup, leading to application failures post-migration.

By having a detailed inventory of your cloud resources and their relationships, you can ensure that the migration follows a clear, logical sequence, maintaining service continuity and reducing risks.

Step 2: Define your IaC migration strategy

Migrating to Infrastructure as Code isn’t a one-size-fits-all approach. Your IaC strategy will depend on business priorities, existing cloud complexity, and desired outcomes.

Common IaC migration strategies:

• Adopt-as-is: Convert your existing cloud infrastructure into IaC without making major changes. This is the fastest approach but may inherit inefficiencies.
• Refactor: Optimise infrastructure while migrating, improving security, performance, and cost-efficiency (ideal for optimising costs during IaC migrations). Optimising your infrastructure through IaC involves refactoring inefficient setups, such as consolidating redundant resources or automating scaling, which can reduce costs and improve performance. For example, by using IaC to automatically scale compute resources based on traffic, you can reduce costs during low-traffic periods while maintaining high performance when demand spikes.
• Rebuild: Redesign your infrastructure from the ground up using IaC best practices—best suited for outdated or inefficient cloud environments.

Pro tip: If your infrastructure is heavily reliant on manual provisioning, a phased approach works best to minimise risks.

Step 3: Choose the right IaC tools

Selecting the right Infrastructure as Code tools is key to a smooth migration. The best choice depends on your cloud provider, environment, and skills and expertise you employ in-house. 

Top IaC tools:

• Terraform: Best for multi-cloud environments and hybrid cloud setups.
• AWS CloudFormation / Azure Bicep: Ideal for teams fully invested in AWS infrastructure as code or Azure IaC.
• Pulumi: Great for developers who prefer writing infrastructure in traditional programming languages (Python, JavaScript, etc.).

Using the same tool across teams can reduce complexity and ensure IaC consistency in migration but may introduce challenges such as importing resources into a TF state file. 

Read blog 2 on which technologies to use for IaC

Step 4: Implement version control and state management

Once you migrate to IaC, tracking infrastructure changes becomes essential. Version control helps prevent conflicts between different versions of your infrastructure code, such as when multiple team members make changes to the same resource or configuration simultaneously. These conflicts can result in errors, downtime, or inconsistent environments. State management ensures that the deployed infrastructure matches the intended state, preventing IaC inconsistencies, which can lead to misconfigurations, security vulnerabilities, or performance issues.

Maintaining IaC consistency ensures that infrastructure is deployed correctly, with all dependencies and configurations in place. This helps reduce errors, improves team collaboration, and strengthens the reliability and security of your cloud environment.

Best practices for version control & state management:

• Store all IaC code in repositories like GitHub, GitLab, or Bitbucket.
• Use remote state management solutions like Terraform Cloud, AWS S3 with DynamoDB, or Azure Storage. Many organisations use Azure DevOps because of tight integration with EntraID and low costs.
• Implement branch-based workflows to ensure only tested and approved changes are deployed.

Why is this important?

Without proper version control, teams risk introducing IaC drift, where manual changes conflict with coded configurations.

Step 5: Test and validate IaC before deployment

Deploying untested Infrastructure as Code can lead to costly outages due to misconfigurations, security vulnerabilities, or incompatibilities with existing infrastructure, all of which can disrupt services and cause downtime. Integrate testing into your workflow to catch issues early.

Key testing strategies:

• Static code analysis: Use Checkov, tfsec, or similar tools to scan IaC for security misconfigurations.
• Pre-deployment validation: Tools like Terraform Plan and CloudFormation Change Sets help preview changes.
• Automated testing: Frameworks like Terratest verify infrastructure behaviour before deployment.

Testing your IaC implementation provides the opportunity to identify and correct faulty code before deployment, reducing the risk of deployment failures. It also allows you to detect security vulnerabilities, giving you the chance to make remediations that bolster your cloud security.

Step 6: Migrate in phases & continuously monitor

Instead of switching everything at once, a phased IaC migration strategy minimises risk.

Best practices for phased migration:

• Start with non-production environments (dev/staging) before moving critical workloads.
• Use monitoring tools like Datadog, AWS CloudWatch, or Azure Monitor to track performance and detect issues.
• Implement IaC drift detection to prevent configuration mismatches.
• Plan for IaC rollback and failover in case of unexpected failures. This involves creating backup copies of critical infrastructure, such as virtual machines or IaC deployments, and implementing automated rollback mechanisms to restore previous configurations quickly. Additionally, failover strategies should ensure that if a deployment fails, the system can automatically switch to a stable, functioning state, minimising downtime.

Why is this important?

A gradual migration prevents or minimises downtime and ensures IaC security without disrupting essential services.

How Claranet helps enterprises migrate to IaC safely

Many organisations struggle with IaC adoption due to the complexity of refactoring existing infrastructure. This challenge is often compounded by limited in-house expertise, as teams may not have the necessary skills in cloud architecture, automation or IaC best practices. Without the full range of required expertise, optimising your infrastructure during refactoring and migration can be a challenge. Claranet's team of Infrastructure as Code experts helps businesses bridge this gap by providing the knowledge and experience needed to successfully adopt and implement IaC. We help organisations:

• Audit and map their current cloud estate
• Define an IaC migration strategy that minimises risk
• Implement secure, automated deployments at scale
• Provide ongoing support for IaC consistency and governance

Transforming a financial services firm with IaC

A major financial services provider faced several challenges as their multi-cloud environment grew increasingly complex. They needed to migrate their infrastructure to IaC in order to improve operational efficiency, reduce manual errors, and streamline their deployment processes. Their existing system was prone to misconfigurations, which led to downtime, slow deployments, and potential security risks. The firm was also concerned about maintaining regulatory compliance while scaling their cloud infrastructure. However, they feared service disruptions during the transition and wanted to ensure a smooth, risk-free migration.

Claranet helped them:

• Map out dependencies and create a phased, incremental migration plan to ensure that each piece of infrastructure was moved without impacting critical services
• Standardise deployments across AWS and Azure using Terraform, ensuring consistency and avoiding errors caused by manual configurations
• Implement automated validation to catch mistakes in the code before it was deployed, preventing misconfigurations that could lead to downtime, security vulnerabilities, or compliance issues

The results?

• 50% reduction in deployment times, allowing the team to release updates and features much faster
• Stronger security through the use of automated policies that ensured compliance and helped identify vulnerabilities before they became issues
• Reduced operational costs by automating previously manual processes, enabling more efficient use of cloud resources and minimising human error

Final thoughts on migrating to Infrastructure as Code

Moving to Infrastructure as Code is a crucial step toward achieving automation, scalability, and cost efficiency. However, without a solid plan, the process can be risky. By following best practices, choosing the right IaC tools, and implementing a structured IaC migration strategy, businesses can modernise their cloud infrastructure seamlessly.

Need help with IaC implementation? Claranet's experts can guide you through selecting, deploying, and optimising the best Infrastructure as Code tools for your business.

Next: Read Blog 5 on future-proofing your cloud with IaC