Understanding Patterns and Antipatterns of IaC and Terraform
In an ever-evolving digital landscape, the seamless integration of development and operations has become a necessity for organizations seeking to achieve unparalleled efficiency and agility. The opening chapter of this book delves into the fascinating world of Infrastructure as Code (IaC) and Terraform, unraveling the key principles, patterns, and anti-patterns that underpin this transformative approach. With a keen focus on idempotency, immutability, and an array of best practices, this chapter illuminates the path to robust, secure, and compliant infrastructure management. As we embark on this captivating journey, we’ll explore the intricacies of IaC projects, examine the challenges they present, and unearth invaluable strategies to conquer them. By the end of this chapter, you’ll possess a solid foundation to make informed decisions about the life cycle of your infrastructure and harness the true potential of IaC and Terraform.
We’ll cover these main topics in this chapter:
- Introducing IAC
- Patterns and practices of IaC
- How to handle IaC projects
- How to make decisions about IaC projects
IaC refers to the process of managing and provisioning computing infrastructure through machine-readable definition files instead of relying on interactive configuration tools or physical hardware setups.
IaC leverages coding techniques that have been tried and tested in software systems, extending their application to infrastructure. It is one of the key DevOps practices that enable teams to deliver infrastructure and software rapidly and reliably at scale. Having a fast and dependable infrastructure provisioning mechanism is essential for organizations that want to achieve continuous delivery for their applications.
In IaC, a declarative language is typically used to describe the desired state of a system, as well as the steps required to bring it into compliance with that state. The IaC tool then uses these descriptions to construct and manage the necessary steps automatically, transitioning the system from one state to another. As a result, IaC enables organizations to automate processes such as resource installation, configuration, deployment, scaling, updating, and deletion in their IT infrastructures.
Key principles of IaC
Idempotency is a characteristic of certain operations in mathematics, programming languages, and computer science. It refers to the property where applying these operations multiple times produces the same result without altering it except for generating identical copies.
In the context of IaC, idempotency means that regardless of the starting state and the number of times the IaC is executed, the end state remains the same. This simplifies the infrastructure provisioning process and minimizes the likelihood of inconsistent outcomes. This property offers several advantages for operations, such as the capability to roll back changes and retry them in case of failure.
One way to achieve idempotency is by using a stateful tool such as Terraform. With Terraform, you can specify the desired end state of the infrastructure, and the tool will handle the process of reaching that state.
Configuration change management is an important topic for infrastructure provisioning. For success, we need a powerful change management recording system that records all changes made to the infrastructure, and it includes details about why those changes were made, who was responsible for them, when they were implemented, and so on.
Configuration drift can pose a significant challenge to infrastructure management. It arises when changes are made to the infrastructure without proper documentation, causing different environments to diverge in ways that are difficult to replicate. This problem is particularly prevalent in mutable infrastructures that are active for extended periods.
The consequence of configuration drift can be severe, leading to inconsistent performance and stability and security issues in the infrastructure. Since it is difficult to reproduce the exact conditions that led to the drift, troubleshooting such problems can be time-consuming and error-prone.
Immutable infrastructure is a technique for constructing and managing infrastructure in a dependable, repeatable, and foreseeable manner. This approach offers several advantages over traditional IT environment management methods. Rather than altering the existing infrastructure, immutable infrastructure involves replacing it with a new one. By provisioning fresh infrastructure each time, the approach ensures that the infrastructure remains reproducible and free from configuration drift over time.
Immutable infrastructure also provides scalability when provisioning infrastructure in cloud environments.
Now that we know what IaC is and what its key principles are, let’s look at the patterns of IaC.
Patterns and practices of IaC
Diving into the world of IaC, it is essential to uncover the patterns and practices that form the backbone of efficient and reliable implementations. In this section, we will explore the fundamental building blocks that contribute to the success of IaC, ensuring a comprehensive understanding of its best practices and a solid foundation for your IaC journey.
Source control and VCS
It is crucial to keep all aspects of your infrastructure, including the smallest scripts and pipeline configurations, in source control or version control systems (VCSs). A version control system is a tool that manages and tracks changes to documents, programs, and other collections of information, often used in software development to maintain a history of code changes.
This practice ensures that you have a record of all changes made to your infrastructure, regardless of how minor they may be. It also simplifies the process of tracking ownership and the history of changes to your infrastructure configurations.
Furthermore, it is important to make the infrastructure code accessible to all members of your organization, including those who do not directly work on the IaC code base. This visibility provides a better understanding of how the infrastructure is provisioned and enables quick troubleshooting of any issues that arise. By reviewing the code, users can gain a deeper understanding of how the infrastructure operates, and even contribute to the development of the infrastructure if they choose to do so.
The visibility and understanding of the applications running on your infrastructure are crucial for managing a successful IT infrastructure. By having a good grasp of how the applications function, you can optimize their performance and ensure that they operate efficiently. By keeping the infrastructure code accessible to all, you can ensure that your entire organization can contribute to maintaining and improving the infrastructure, ultimately leading to better outcomes for your business.
Modules and versions
Refactoring IaC is difficult compared to application development, particularly for critical pieces such as DNS records, network configurations, databases, and so on.
In many organizations, team structures and responsibilities are different, so it will make more sense to separate multiple layers of infrastructure and assign governance to the respective teams. In some cases, there might be some more separated layers needed for cross-functional teams managing both infrastructure and application development.
The following diagram illustrates an example of Amazon EKS deployments, featuring multiple modules for each infrastructure layer and their respective governors. It is important to note that the modules and layers depicted in this diagram may differ depending on your specific setup.
Figure 1.1 – EKS deployment workflow
Versioning for modules is quite important to provide support for multiple versions of services that can operate without breaking the existing production resources.
IaC minimizes the need for extensive documentation for infrastructure since everything is codified and stated as a declarative manifest. However, some documentation is needed for better infrastructure provisioning so that consumers can understand and improve the current modules and templates.
Documentation can be challenging to manage, much like code. It is critical to provide sufficient documentation to convey the intended message effectively. However, having more documentation does not necessarily equate to better-quality documentation. In fact, outdated documentation can be more detrimental than having no documentation at all.
IaC documentation must live close to the code. Keep it close so that everyone can update the documentation without unnecessary effort and difficult steps. If you can build good governance automation, documentation creation or updates can be easily tracked and enforced.
An effective approach to managing documentation for IaC is to include a
README file within the same repository as the code, rather than using an external platform such as Confluence or a wiki. This approach facilitates updating the documentation during the same commit as the code changes, which is particularly useful as a reminder during the pull request process.
It is also ideal to leverage automated tools to generate documentation from the code or use tests as documentation. By doing so, you can ensure that the documentation stays in sync with the code, reducing the likelihood of inconsistencies and outdated information. This approach can also streamline the documentation process, reducing the need for manual documentation efforts and enabling faster iterations.
Software testing is the process of executing a program or application with the intent of finding errors. Testing can be done at various levels, from unit testing to integration testing to system testing and acceptance testing.
IaC development is not an easy task. There are many different aspects and considerations that need to be taken into account before, during, and after the development process. One of these considerations is how to test your IaC. Let’s provide you with a basic understanding of the various levels of testing that you need to think about when developing your IaC:
- Static code and analysis
Running quick tests as frequently as possible is crucial for obtaining prompt feedback during the development process. This approach is especially effective when performed on your local machine. There are various integrations available that can automate this process and trigger tests automatically when you save a file in your text editor or IDE.
To perform static analysis, you can use specialized tools such as Terraform Validate or TFLint. These tools enable you to identify issues in your code and configurations promptly, reducing the likelihood of errors and inconsistencies in your infrastructure. By incorporating quick testing and static analysis into your development process, you can streamline the testing process and improve the reliability of your infrastructure.
- Unit testing
Since many IaC tools, such as Terraform and Ansible, operate on a declarative model, unit testing may not always be necessary. However, in some cases, unit tests can be beneficial, particularly when conditionals or loops are involved.
While unit testing may not always be required for IaC, incorporating it where necessary can help to catch potential issues early on in the development process, improving the overall quality of your infrastructure.
- Integration testing
One essential step in ensuring the reliability of your infrastructure is to perform validation testing. This involves provisioning resources in a test environment and verifying whether specific requirements are met. It is crucial to avoid writing tests for things that are already covered by your IaC tool, particularly when working with declarative code.
For example, instead of verifying whether the policies specified in IaC were applied, you should write automated tests to ensure that none of your S3 buckets are public. Similarly, you can test that only specific ports are open across all of your EC2 instances. To perform these tests, you can provision an ephemeral environment that you can later tear down.
Depending on the duration of these tests, you may want to run them after every commit or as nightly builds. By incorporating validation testing into your development process, you can catch potential issues early on, reduce the risk of errors, and ensure the overall reliability of your infrastructure.
- Smoke tests
An additional approach to testing is to provision an environment, deploy a dummy application, and run quick smoke tests to verify that the application has been deployed correctly. Using a dummy application can be helpful in testing scenarios that your actual application may encounter but are not configured for production.
For example, if your application connects to an externally hosted database, you should attempt to connect to it in your dummy application. By doing so, you can gain confidence that the infrastructure you are provisioning is capable of supporting the applications you intend to run on it.
As these tests can be time-consuming, it is advisable to run them after provisioning a new environment and periodically thereafter. By leveraging this testing approach, you can ensure that your infrastructure is capable of supporting your application’s requirements and minimize the risk of errors or issues arising during deployment.
Security and compliance
The definition of IaC is to provide an abstraction layer between the physical infrastructure and the applications that run on top of it. This is done by separating the hardware from the software and by abstracting out all of the tasks that are required to manage the hardware.
IaC can be used by companies for compliance purposes, such as HIPAA, SOX, PCI DSS, and so on. It can also be used for security purposes, such as preventing unauthorized access to data or preventing hackers from accessing sensitive information.
Let’s look at important details of security and compliance.
Identity and access management
Implementing a strong Identity and Access Management (IAM) strategy is essential for safeguarding both your IaC and the infrastructure it provisions. One effective approach is to use Role-Based Access Control (RBAC) for IaC, which can significantly reduce the overall attack surface.
By leveraging RBAC, you can grant just enough permission to your IaC to perform the necessary operations while preventing unauthorized access. This approach helps to minimize the risk of errors or malicious activity, improving the overall security of your infrastructure.
When working with IaC, it is common to require secrets to provision infrastructure. For example, if you are provisioning resources in AWS, you will need valid AWS credentials to connect to it. It is crucial to ensure that you use a reliable secret management tool, such as HashiCorp Vault or AWS Secrets Manager, to manage these sensitive credentials.
In cases where you need to store or output secrets in the state file (although it is advisable to avoid doing so), it is essential to encrypt them to prevent unauthorized access. By encrypting secrets stored in the state file, you can mitigate the risk of exposure in the event of a security breach or unauthorized access.
Performing security scans after provisioning or making changes to infrastructure in a lower or ephemeral environment can help mitigate potential security issues in production. Leveraging tools such as CIS Benchmarks and Amazon Inspector can be effective in identifying common vulnerabilities or exposures and ensuring adherence to security best practices.
By conducting security scans, you can catch potential security issues early on in the development process and prevent them from being carried over to production. This approach helps to minimize the risk of security breaches and protect sensitive data and infrastructure.
Compliance requirements are a critical consideration for many organizations, particularly in highly regulated industries such as healthcare or finance. These industries are subject to stricter requirements, including HIPAA, PCI, GDPR, and SOX, to name a few. Traditionally, compliance teams conducted manual checks and filled in paperwork to ensure adherence to these requirements.
However, automation tools such as Chef InSpec or HashiCorp Sentinel can help streamline compliance requirements and improve efficiency. By automating compliance checks, you can run them more frequently and identify issues much faster. For instance, you can incorporate compliance tests into your IaC pipeline by provisioning an ephemeral environment and running tests every time you modify your IaC code. This approach enables you to catch potential compliance issues early on and rectify them before they impact production systems.
How to handle IaC projects
In today’s fast-paced digital landscape, IaC has become a critical consideration for organizations of all sizes. With IaC, developers can create the machines or resources required to run their applications easily, saving time and effort in the process. As your organization scales, IaC can help your developers focus on solving more complex problems, rather than getting bogged down in manual resource configuration.
However, it can be challenging to ensure identical, error-free, secure, and compliant configurations across different environments. This is where IaC comes in. By defining your infrastructure as code, you can make changes or add new resources by updating a piece of code, and the IaC tool will handle the configuration for you.
By adopting IaC, organizations can improve agility, speed, and consistency in resource provisioning and configuration. This enables developers to focus on delivering high-quality applications, while operations teams can manage infrastructure at scale with greater ease and efficiency.
Let’s have a look at the challenges we can face.
At the heart of IaC is the concept of defining your infrastructure in code. By using a declarative syntax, you define the desired final state of your infrastructure, and the IaC tool takes care of the underlying dependency resolution and resource launching steps.
To keep track of changes made to your infrastructure, you can store this code in a VCS. This not only provides you with an audit trail of who made changes but also enables you to revert to a previous version if needed.
Automated quality, compliance, and security tests can also be run on your infrastructure, allowing you to verify its compliance without investing days or weeks of effort.
By adopting IaC, your developers can avoid the tedious and error-prone task of manually defining steps or scripts to launch and configure resources. Tools such as Terraform and CloudFormation are widely used to achieve these tasks, enabling organizations to achieve greater agility, scalability, and consistency in infrastructure management.
Version control systems for IaC
VCSs also offer a simple way to track and audit changes made to the code base, including infrastructure changes. By using pipeline features within a VCS, such as those available in GitHub or GitLab, you can enforce policies and ensure that changes meet the necessary criteria before they are deployed to production.
Some common use cases of IaC
IaC is commonly used to launch infrastructure across various cloud providers, as well as for provisioning machines upon launch. Popular tools for provisioning with IaC include Chef, Ansible, and Puppet, while Terraform and CloudFormation are commonly used for infrastructure provisioning.
IaC can also be used to deploy applications, such as with Kubernetes, by leveraging tools such as Jenkins or Ansible. In upcoming chapters, we will delve further into using IaC with Kubernetes.
Challenges and best practices with IaC
Adoption within the team
Integrating IaC into your organization can present a learning curve and a change in processes. Your team may need to become familiar with the language used to write IaC code and develop pipelines to execute the code. If your team is accustomed to making changes from cloud consoles and is operation-centric, transitioning to IaC can be a significant shift for them.
You can see huge, powerful resistance to learning new technologies or practices. Be ready to fight, and always be an evangelist of infrastructure automation, security, and compliance.
At the start of an IaC journey, developers may not always know what changes are required for infrastructure provisioning and may opt to make changes manually via the console. This can lead to configuration drift, where the deployed infrastructure does not match the code definition, potentially causing outages or issues with future updates. To prevent this, it is important to educate the team on the consequences of manual changes and discourage their use.
To further mitigate the risk of configuration drift, you can build automation to detect drifts and ensure that only authorized personnel have access to make changes in critical environments. This can help ensure that your infrastructure remains consistent and secure.
When using open source modules in your IaC pipeline, it is important to ensure that they are secure and free of vulnerabilities. Before using any open source project, it is recommended to verify that it is safe to use.
To maintain a high level of security, it is essential to establish static code analysis pipelines and continuously scan open source modules. This way, any vulnerabilities can be detected and addressed promptly.
To prevent misconfigurations from entering production, it is crucial to catch validation errors that may be introduced when a developer makes changes. With Terraform, you can easily implement a validation step using the Terraform plan functionality. It is essential to have a full understanding of the plan outputs before applying them to ensure that no unexpected changes are made to your infrastructure.
Side effects of automation
In IaC, a lot of code will be reused as you automate infrastructure creation. However, any small misconfiguration can propagate across a large set of resources very easily. Therefore, it’s crucial to catch these errors during the pipeline verification stage.
To prevent unexpected changes to existing resources, always use versioning when updating modules.
Keeping up to date with cloud providers
Changes to cloud providers’ APIs and policies can affect your existing infrastructure, which means that you need to update your tools and code. This can be especially difficult if you’re using open source tools, as updates may not be immediately available. If there is a delay in releasing changes, it can result in incorrect permissions or issues with provisioning access to machines if the RBAC API changes. Therefore, it’s essential to keep your tools and code up to date with the latest API changes and policies to ensure your infrastructure continues to function properly.
Maintainability and traceability
Having a well-defined procedure for promoting infrastructure changes to the production environment and assigning responsibilities is crucial to ensure that all changes are properly verified. This helps to avoid chaos and maintainability issues on the VCS side.
Furthermore, traceability is an added advantage of using VCSs as all changes are logged and can be easily tracked. For instance, Git provides the Git log command and commit history to view all changes made to the code.
Many IaC tools, including Terraform, lack an intrinsic RBAC feature, a crucial element that governs who has permission to access, manage, and execute specific resources and operations. In the absence of native RBAC, these tools are dependent on the underlying platform or VCS where the code resides. Consequently, it’s assumed that individuals executing the code possess the requisite permissions, transferring the onus of managing and enforcing RBAC to the VCS. This can involve setting up specific access controls, permissions, and restrictions within the VCS to ensure that sensitive and critical infrastructure configurations are only accessible and executable by authorized personnel, thereby maintaining security and compliance standards.
VCS and proper approval flows
It is essential to implement version control in your IaC workflow to maintain control of your code, track changes, and facilitate auditing. It is also important to establish a process where changes cannot be merged into production without proper approval and validation. One option is to incorporate validations into the Continuous Integration (CI) process of GitHub or GitLab. By treating your IaC code like any other application code, you can ensure that your infrastructure is an integral part of your overall system.
Handling secrets properly
You need to manage two types of secrets in your IaC pipeline. The first type of secret is used to create resources in the cloud, and only the admin of the repository should have access to them. For this purpose, you can use a secret variable in GitHub or GitLab.
The second type of secret is generated when the code is executed, such as the password for an IAM user in AWS. It’s crucial to ensure that these secrets are not getting logged anywhere and are securely transmitted to users.
Consider applying the principle of immutable infrastructure if you need to make changes to your infrastructure. This approach involves creating a new machine with the required changes and replacing the old machine with the new one, instead of modifying the existing machine. By doing so, you can ensure that your changes are in line with the code, and there are no snowflake server states. The concept behind immutable infrastructure is to manage machines entirely through code, and no manual changes should be made.
Validations and checks
By implementing checks and validations in the CI pipeline, you can catch security issues and misconfigurations on the left side of the pipeline. This helps increase the frequency of the development cycle and maintain the security of each release.
Infrastructure as code and Kubernetes
Using the same principles as IaC, you can deploy your application on Kubernetes. Kubernetes objects are declarative files that can be defined and stored in a code repository. These files can then be applied to a Kubernetes cluster using a controller to deploy your application.
Despite the many advantages of IaC, there are also several challenges that must be addressed to ensure the success of the implementation. These include the need for proper validations and checks, as well as a well-established process to avoid security lapses that can lead to increased costs and compromised environments.
Fortunately, the emerging practice of GitOps combined with IaC enables faster and safer rollout of changes, resulting in quicker deployment cycles and large-scale auditing. IaC is not only the present but also the future of managing infrastructure, applications, and tooling, and its adoption is highly recommended for reducing operational costs.
How to make decisions about IaC projects
IaC is not just about configuration management and deployment; it also provides the ability to manage infrastructure with code. The code can be used to automate activities such as application deployment, configuration management, and continuous delivery.
Here are a few plus points to consider:
- It is easy for developers to get started with IaC because the documentation is available in a single place
- It allows for more efficient collaboration between development teams by providing an easy way to share configurations with other members of the team
- It reduces errors in configuration management by making them easier to reproduce
Let’s have a look at the decision points that will improve the maturity level of IaC projects.
The decision about where to store your code
Storing IaC files using a VCS is essential for tracking changes and collaboration. While any cloud storage system can be used, Git has become the de facto standard for IaC versioning. Originally designed for storing code, Git can be used as the primary source for deploying infrastructure code. Several solutions, such as GitHub, GitLab, and Bitbucket, offer free SaaS for public repositories, while community editions can be self-hosted. Using Git should be a basic skill set for any developer or cloud or DevOps engineer looking to start an IaC project successfully.
The decision about how to structure your code
Once you have chosen where to store your IaC code, the next step is deciding on how to structure it. The structure you choose will depend on the complexity of your organization and IT environment. There are several options, including using a mono-repo for all your IaC code, having a separate repository for each tool or language used, or having a repository for each application server or infrastructure type.
In addition, you need to determine a branching strategy that works well for your team. It’s essential to discuss and agree on this with your team to ensure everyone is on the same page.
It’s recommended to start with a simple structure and evolve it over time based on your needs. Alternatively, you can put more thought into the structure beforehand to prevent potential rework later. Whatever structure you choose, make sure it’s easily adoptable by all team members. Create clear documentation on the structure and decision-making process so that new team members can quickly understand and start contributing effectively.
The decision about how to run your code
To gain better control over your infrastructure, it is recommended to use a CI/CD tool such as Jenkins, GitLab CI, or GitHub Actions to run your IaC. With these tools, you can trigger jobs manually, via webhooks or on a schedule, and have a record of every job that has run. Additionally, the jobs run from an agent can be pre-configured with the necessary tools, reducing the chances of errors due to different tool versions. It is important to choose the right tool that fits your needs and configure it properly to ensure its effectiveness.
The decision about how to handle your secrets
When provisioning automated infrastructure, it is crucial to store secrets such as database passwords and logins securely. It is not advisable to store them in your repositories, even if the repository is only accessible within your own network and protected with multi-factor authentication.
When using Git tools, all the credentials are copied to your machines and the machines of your team members when they clone the repository, making them vulnerable to security breaches.
A better solution is to use a vault system that can encrypt your secrets and inject them as environment variables during the runtime of your pipeline. It is ideal to have security enabled on multiple layers, so even if one layer is breached, there is a second line of defense to protect your sensitive information.
The decision about a common set of tools
To kickstart IaC projects effectively, it’s important for the team to agree on a consistent set of tools. While there may be several ways to achieve the same objective, it’s beneficial to explore simpler, quicker, or more cost-effective methods. Using a common toolset makes it easier to share and reuse building blocks. Striking a balance between granting engineers the freedom to experiment with new tools and standardizing on a common set of tools is crucial. Certain tools work well in tandem, while others don’t, and paying for redundant licenses is generally not a good idea.
The decision about the level of pipelines
When using pipelines to run your IaC, there are various methods to achieve the same outcome. It’s essential to use a naming convention and provide clear descriptions to help others understand the purpose of a pipeline. You can consider dividing a pipeline into multiple stages, so you have the flexibility to rerun or skip a stage depending on the type of deployment. Then, decide whether you want to enforce mandatory reviews, require approval from a manager, or give developers the liberty to deploy themselves during go-live.
The decision about the life cycle of your infrastructure
The level of testing and validation required for a proof-of-concept script versus code developed for large-scale deployment is significantly different. Robust code requires more comprehensive testing and validation efforts, which requires additional time and resources.
In an ever-evolving world, infrastructure must also be adaptable to changes such as security updates, service improvements, and new service types. While using SaaS/PaaS services can reduce the maintenance workload, it comes at a cost. Furthermore, even these services will evolve over time, necessitating engineering efforts to keep up. There are various strategies and practices available to simplify this process, each with its own benefits and drawbacks. It’s important to determine the approach that works best for your specific situation.
This first chapter on understanding patterns of IaC and Terraform covered the key principles of IaC, such as idempotency and immutability. The chapter also discussed various patterns and practices of IaC, including source control, modules, versions, documentation, and testing. The chapter also covered security and compliance concerns, such as IAM, RBAC, secret management, security scanning, and compliance.
It also provided guidance on how to handle IaC projects and the decisions involved in starting IaC projects. Additionally, the chapter highlighted the challenges and best practices of IaC, including the importance of standardizing toolsets, naming conventions, and clear descriptions, and the need for a proper process for approvals and validation in the CI pipeline.
Overall, this chapter provided a comprehensive overview of the principles and best practices of IaC and highlighted the importance of adopting these practices to improve the agility, efficiency, and security of infrastructure management.