If you’re a DevOps engineer looking to advance your career, you’ve probably heard of infrastructure as code (IaC). Infrastructure as code has emerged as a key component of the DevOps movement, which aims to improve communication and collaboration between development and operations teams.
Among the benefits of IaC are the ability to manage infrastructure declaratively and version control infrastructure changes, as well as collaborate on those changes with other team members.
In this article, you’ll learn about the fundamentals of IaC and how it can help you build an infrastructure as code pipeline. You’ll also look at how you can use some popular IaC tools to help you implement automatic and versioned infrastructure provisioning.
Infrastructure as code in DevOps
Infrastructure provisioning has always been a challenge, dating back to the days when the only way to increase capacity was to either add more servers to your data center rack or upgrade the servers in that rack. Provisioning new servers was a time-consuming and error-prone process that used to take weeks or even months, sometimes with frantic trips to places like eBay to help make ends meet.
When cloud computing entered the picture, it also came with an API that allowed you to provision thousands of instances in seconds and eliminate the physical dependency of managing the logistics of your hardware. Teams began communicating with the API, either by portal or by code, to create instances as needed without incurring any CapEx (capital expenditures, aka purchasing physical goods). Unfortunately, this came with some significant drawbacks. Infrastructure knowledge remained in the hands of a single person or a small group of people, and transferring this knowledge was difficult when new members joined or a key employee left the organization. Things being siloed into a few people or even one person invited the “bus factor” into the equation. If any of those important people left the company, that could spell disaster.
Moreover, even with the advantages that cloud computing offered, infrastructure provisioning remained an error-prone and slow, manual process. For example, human error issues crept in when changes to the running environment were not recorded or communicated to the appropriate people. Documentation of the infrastructure setup became out of date the moment it was written and was regarded with the same casual loyalty as scribbling on a napkin to kill time. It was a mess.
Compliance and audit issues also tended to arise as a wide range of services were running and being updated without a blueprint of the infrastructure; you can’t know if you are patched against a security issue unless you know what machines are potentially affected.
Advantages of Infrastructure as Code
The advent of IaC meant infrastructure provisioning became much easier, faster, and more reliable, and many of the shortcomings mentioned above were eliminated. You could even say that IaC brought the same benefits to infrastructure that DevOps brought to software development.
Specifically, you can continuously create, destroy, and update your infrastructure using the same process and tools you use for your application code as dictated by your DevOps practices. This means that using IaC gives your infrastructure the same benefits that a DevOps workflow gives your code. You can also use the same collaboration and review tools to track your infrastructure changes as you do your code changes. This makes it much easier to manage and understand your infrastructure, and to identify and fix problems quickly.
IaC also makes it easier to automate infrastructure provisioning, saving a lot of time and effort. It can even eliminate the need for manual intervention altogether. This can greatly improve the speed and reliability of your infrastructure provisioning process and make it much easier to scale your infrastructure up or down as needed. Need to spin up more servers? Add a line to the code. Need to spin those servers down? Remove that line from the code. It’s really that easy.
Overview of infrastructure as code
A clear understanding of what IaC tools bring to the table can help teams and enterprises understand its significance. Among many benefits, the ones that stand out are cost savings, agility, and less risky deployments.
Saving money is a key consideration for organizations, and IaC is a good way to go about it. When you use IaC tools, the knowledge of infrastructure is stored in code as opposed to in people; as such, you can run efficiently with smaller infrastructure provisioning and management teams. Furthermore, because these tools provide consistent and automated deployments, there are savings in the form of reduced error and high availability.
Large businesses can lose millions of dollars for every minute of downtime, so avoiding downtime due to misconfiguration issues is a sure way to save money. When you use IaC tools, you also have less overhead because the configuration code is easy to maintain, and you can understand the dependencies between different resources by looking at the source.
Finally, the ability to deploy code and infrastructure quickly and in a repeatable manner allows you to reach the market faster because your focus is on the core business logic rather than the error-prone task of manual management and provisioning of infrastructure.
Modern software delivery practices are all about speed and agility. IaC can allow teams to rapidly adapt to traffic spikes by automatically provisioning and configuring resources as needed. For example, say you’re running a cluster with five nodes and receiving ten thousand requests per second. Suddenly there’s a spike of nineteen thousand requests per second. If you were to scale up manually, adding and configuring the necessary capacity would take hours. With the appropriate IaC tools, you simply scale up the cluster to ten nodes, and the doubled capacity would be available almost immediately.
The most helpful part is that changing a few parameters can help you generate QA, preprod, and production deployments without the hassle of starting from scratch.
Secure services are very important when dealing with applications and data. Configuring these services is often difficult to do without introducing security vulnerabilities.
Infrastructure as code can help mitigate these risks by automating the provisioning of these services, which can help ensure that they’re configured securely and consistently. You don’t need to open an interface to your portal to configure things manually and worry about hackers sneaking in through back doors. Also, because these processes are now automated, they can be easily repeated should something go wrong.
Finally, IaC can help make setting up new servers easier and more repeatable. This can help ensure that new servers are configured correctly and securely from the outset.
IaC methods and protocols
No one tool can be used to perform everything, so having specific tools that are suitable for the task at hand is always going to be more efficient. That being said, infrastructure as code can be broadly classified into a few categories: imperative or declarative, and push or pull.
Imperative vs. declarative
Imperative IaC is where you write code that explicitly details every step required to provision your infrastructure. This is often referred to as procedural code. An example would be using a shell script to provision and configure a virtual machine.
By contrast, declarative IaC is where you write code that specifies the desired state of your infrastructure. Using a tool like Terraform to configure and deploy a set of virtual machines or container orchestrators like Kubernetes is an example of this. You specify which provider you want the cluster in and supply the tool with plug-ins and authentication tokens. After you apply the changes, the tool takes care of the rest.
The main difference between the two approaches is that with imperative IaC, you have to write code to specifically detail every step required to provision your infrastructure. This can be time-consuming and error-prone.
With declarative IaC, you only have to write code to specify the desired state of your infrastructure, and the IaC tool figures out what it needs to do in order to meet that state. As this is less time-consuming and error-prone, most popular tools (such as Terraform and Pulumi) use a declarative approach.
Push vs. pull configuration
The push configuration works by sending configuration files to servers from a central repository. The approach is very simple and straightforward to implement. All you need is a central repository and a method to move files from the repository to the servers.
The main disadvantage of the push approach is that it can be slow and inconvenient if you have a large number of servers, as any changes to the configuration must be pushed to all of the servers.
The pull configuration means that the servers check the central repository for changes on a regular basis and download the most recent configuration files. When you have a large number of servers, the main advantage of this approach is that it’s much faster and easier to manage. This is due to the fact that you need to make changes in only one place (the central repository), and the servers will automatically pull them down.
The main disadvantage of this approach is that it’s more difficult to set up (most IaC tools are designed with the push model in mind) and may cause conflict if changes are made in the server before the pull is completed. However, this is unlikely to be an issue because playing in a live environment is not advised and tends to be restricted.
The pull method is more popular and efficient because it allows for testing prior to infrastructure deployment. It also allows for centralized storage of your configuration, reducing conflict and serving as a single source of truth that your team can use as a reference.
Common tools for infrastructure as code
As IaC has grown in popularity, many projects have emerged from enterprises and individual contributors serving different use cases. You don’t need to research all of them to get started; below, you’ll find some of the top IaC tools available on the market right now.
All of the tools listed below have an open source version as well as an enterprise edition that you can use for your business needs; the paid versions come with additional features, support, and security.
Hashicorp created the most popular project on the list. Unlike the others, Terraform (which is written in Go) is a tool for provisioning, managing, and configuring infrastructure resources as opposed to configuration management. System administrators and DevOps professionals frequently use it. Terraform is open source and therefore completely free to use. It’s simple to learn and has widespread community support.
The tool supports a declarative infrastructure configuration written in HashiCorp Configuration Language (HCL) and can produce immutable infrastructure without the use of an agent. Terraform allows developers to easily provision entire cloud landscapes, including VPCs, compute instances, and DNS entries. It also works with a number of well-known cloud providers like AWS, Azure, and GCP.
- Advantages: * It enables users to define and provision a data center infrastructure using a high-level configuration language known as HCL.
- It’s capable of managing both popular service providers and custom in-house solutions.
- It’s open source, providing a community in which users can collaborate and contribute modules for popular services.
- Disadvantages: * The learning curve can be steep for those who are not familiar with IaC or HCL.
- When provisioning large infrastructures, the tool can be slow.
- The state files can be difficult to manage when collaborating with a team, but there are options to store these state files in shared spaces, such as AWS S3.
- Writing and using modules requires you to run
terraform initmany times in order to modularize your configuration. There are no functions or equivalent concepts in Terraform. Only modules. This can scale badly.
Pulumi is an IaC tool written in Go. It does everything that Terraform can do, but allows users to write their provisioning instructions in languages like Go, TypeScript, or Python instead of having to use bespoke configuration languages like YAML or HCL.
Writing your configuration in a normal programming language allows users to let their IDE have deep integration into the attributes and parameters of a given resource, unlike Terraform, where users are advised to have the documentation open constantly while developing their infrastructure manifests. It works with major infrastructure providers such as AWS, Microsoft Azure, Google Cloud, and any Kubernetes cluster.
- Advantages: * Writing your own code in a real programming language makes it easier to context switch toward maintaining infrastructure if you are in a programming role.
- Modularization is far easier than with Terraform. Programming languages typically have native facilities for modularization that can work a lot better than with Terraform’s modules concept.
- Pulumi is also open source code and widely loved by the developer community.
- Disadvantages: * Using a fully Turing-complete programming language means that there is the capability of creating an infrastructure plan that will not terminate.
- Bugs in your infrastructure code can result in large unexpected amounts of infrastructure spend.
- Pulumi isn’t as widely adopted as Terraform, so some infrastructure providers may not be available.
Configuration management tools
Provisioning your infrastructure isn’t the end of the story. Once you have the servers created, you will need to configure them to do what you want. This is also a process traditionally fraught with manual human intervention and wishful thinking as documentation. These tools are the best in class for letting you declare what you want your computers to contain, then setting them off to make sure it happens.
Ansible is another well-known configuration management and orchestration tool. Created by Michael DeHaan in 2012, it was purchased by Red Hat in 2015. Ansible playbooks are written in the YAML language. It communicates between nodes using SSH and doesn’t require agents to be installed on remote nodes. It’s written in Python, and Ansible modules and plug-ins can be easily extended by developers.
It’s worth noting that Ansible was primarily created as a configuration management tool. Support for having Ansible manage infrastructure such as AWS is a fairly recent innovation. It’s kind of both an IaC and a configuration management tool, but it’s more mature as a configuration management tool.
For configuration management, the tool employs push methodology in which configurations are pushed from a central server (or developer laptop) to all nodes or target hosts. Community support is strong for Ansible, with more than 35,000 modules and a lot of forums.
- Advantages: * It’s agentless, so there’s no need to install any additional software on your servers.
- It’s very powerful and can be used to manage complex deployments.
- It’s open source and therefore cost effective.
- Disadvantages: * Because Ansible is agentless, it relies on SSH for communication with remote servers, which can be a security concern. You can use a solution like Tailscale to protect your connection and harden your connections.
- Ansible is not as widely used as some of the other options, so less community support is available.
- It’s challenging to learn and use for those without a good understanding of system administration and DevOps concepts.
Chef is a configuration management tool for installing and managing software on existing servers. Its configuration language is a custom domain-specific language (DSL) based on Ruby. The tool uses a pull-based approach to sync changes and produces mutable changes. Chef is popular for its integration with cloud providers.
The tool comes with issue detection in preproduction environments and provides complete security with compliance visibility across all stages.
- Advantages: * Organizations can avoid costly security issues by testing for security and compliance early on in the development process.
- Automating configuration defined in code can help embed security tests in the delivery process.
- Organizations can automate across heterogeneous infrastructure to ensure servers return to their desired state.
- Disadvantages: * It doesn’t support push-based IaC.
- It’s a complex tool that can be difficult to learn if you’re not already familiar with Ruby and procedural coding.
Puppet is a free and open source configuration management system that can aid in the automation of repetitive tasks, the deployment of applications, and the management of system configurations across a group of servers.
This tool created by Puppet Labs is written in Ruby. The Apache License 2.0 governs its distribution. Puppet uses the declarative approach and is appropriate for Unix-like and Microsoft Windows systems.
- Advantages: * Puppet is declarative, meaning that you only need to describe the desired state of your infrastructure.
- It’s idempotent, meaning that it will only make changes to your infrastructure in order to reach the desired state. This means that you can run Puppet as often as you like without fear of breaking things.
- The tool is powerful and flexible, allowing you to manage everything from simple files and packages to complex networks and cloud deployments.
- Disadvantages: * Puppet can be complex to learn and use, especially if you’re not familiar with programming concepts.
- Sometimes it can be slow, especially when you’re managing a large infrastructure.
- Procedures can be difficult to debug.
SaltStack is a powerful open source configuration management and remote execution tool. It can be used for many processes, such as managing server deployments and automating tasks. It follows a declarative approach, meaning that you describe the desired state of your system and SaltStack takes care of the rest.
- Advantages: * It’s a platform with a simple solution that works very effectively.
- It is powerful and flexible, as it automatically detects issues and forces the system to return to the desired state.
- It ensures critical infrastructure is always available.
- Disadvantages: * Community support for the tool is limited.
- The learning curve is steep when you’re getting started.
- It’s not well suited for large environments as there is limited support for hardware.
CFEngine is another powerful configuration management tool for automating system administration tasks. It allows you to define and manage your system’s configuration as well as automate complex tasks such as deployments and system updates.
The tool is used by companies such as Samsung and DHL.
- Advantages: * CFEngine supports patch management on your infrastructure.
- Infrastructure hardening is also supported.
- CFEngine helps with compliance automation by performing audits and checking systems every five minutes to ensure they’re always enforced and adhering to your compliance framework.
- Disadvantages: * There’s no native integration for cloud as with the other tools.
- There’s no existing push mechanism.
Nix and NixOS
NixOS is a next-generation set of tools that lets you describe precisely what a server should run and all of the settings that are normally specified by all the bespoke configuration languages in use on an average production-worthy Linux system. By having deep integration with its package manager Nix, it can also automatically rebuild your custom software as a part of the deploy process. This allows you to describe exactly what you want and have the confidence to know exactly what is going on.
Packages and system configurations are defined in the same language (also called Nix), meaning that your custom packages can be as deeply integrated into the system as with the services that NixOS exposes with its options system. Your configuration for your custom services can be expressed right next to your nginx configuration to expose them to the internet.
- Advantages: * NixOS gives you the ability to know everything that is going on with a system. This makes triaging security issues trivial. Once the vulnerable package is identified, it’s trivial to create a mapping of every other package that depends on it. This helps you evaluate the “splash damage” of remediation efforts.
- Nix is a functionally pure package manager in the sense that package builds cannot randomly access the internet or random parts of the system. This means that even if one of your dependencies has a compromised build script, it cannot phone home with secret credentials.
- NixOS is one of the largest open source repositories on GitHub and has been steadily gaining adoption as years go by.
- The architecture of NixOS makes it difficult for most attack tools to work because it doesn’t place critical system files in standard locations. This is security by obscurity at best, but it does work.
- Disadvantages: * Nix the package manager, Nix the configuration language, and NixOS the operating system are all different things but have nearly identical names. This can lead to ontological confusion.
- The Nix language syntax looks a bit like Haskell and JSON thrown into a blender, with semicolons at the ends of some statements like C. This can prove difficult for newcomers at first, but usually is not a practical issue in the long run.
- Nix and NixOS don’t define push tooling in its core, but there are facilities for having a machine periodically pull its configuration and rebuild itself from a shared Git repository.
This article has covered the fundamentals of infrastructure as code: what it is, why it matters, and how to get started. With knowledge of some of the more popular tools on the market, you should now be better equipped to begin managing your infrastructure in a more efficient and effective manner. Remember that IaC is just one of many tools in your DevOps toolbox and that protecting the tools from external threats is also critical.
Tailscale is a cloud-based solution that integrates with your SSO to secure access to your servers, cloud instances, and tools. It uses WireGuard® to encrypt your connection between you and your servers. This can augment existing infrastructure as well as make it easy to extend into more complicated infrastructure setups. Tailscale also provides a Terraform provider to allow you to automate things further. Want to automatically create authentication keys for new servers you provision? You can do that with Tailscale’s Terraform provider.
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Frequently Asked Questions
Here are some common questions about infrastructure as code, and their answers.
How does IaC improve DevOps?
Using IaC makes it easier to automate infrastructure provisioning, which saves time and effort, makes scaling much simpler, and reduces human error. It can give you the ability to version control infrastructure and manage it declaratively, further increasing efficiency. It also simplifies sharing information about your infrastructure, since that knowledge is stored in code, as opposed to in people.
What’s the difference between imperative IaC and declarative IaC?
With imperative IaC, you are required to write code (often called procedural code) to specify each step that is required to provision your infrastructure, which can be a time-consuming and error-prone process. By contrast, with declarative IaC, you write code only to specify the desired state of your infrastructure, and the IaC tool determines what it needs to do in order to meet that state.
What is a push configuration vs. a pull configuration?
The push configuration works by sending configuration files to servers from a central repository. This approach is simple to implement, but it can be slow and inconvenient if it involves pushing configuration changes to a lot of servers.
In a pull configuration, servers check the central repository for changes on a regular basis and download the most recent configuration files. This is faster and easier to manage than the push configuration, but it can be more difficult to set up, and conflicts may arise if changes are made in a server before one of its pulls is completed.