Introduction to Terraform

Terraform is an infrastructure as code (IaC) tool that allows you to build, change, and version infrastructure safely and efficiently. This includes low-level components such as compute instances, storage, and networking, as well as high-level components such as DNS entries, SaaS features, etc. Terraform can manage both existing service providers and custom in-house solutions.

Below, HashiCorp co-founder and CTO Armon Dadgar describes how Terraform can help solve common infrastructure challenges.

Introduction to Terraform

Terraform is an infrastructure as code (IaC) tool that allows you to build, change, and version infrastructure safely and efficiently. This includes low-level components such as compute instances, storage, and networking, as well as high-level components such as DNS entries, SaaS features, etc. Terraform can manage both existing service providers and custom in-house solutions.

Below, HashiCorp co-founder and CTO Armon Dadgar describes how Terraform can help solve common infrastructure challenges.

»Key Features

»Infrastructure as Code

You describe your infrastructure using Terraform's high-level configuration language in human-readable, declarative configuration files. This allows you to create a blueprint that you can version, share, and reuse.

»Execution Plans

Terraform generates an execution plan describing what it will do and asks for your approval before making any infrastructure changes. This allows you to review changes before Terraform creates, updates, or destroys infrastructure.

»Resource Graph

Terraform builds a resource graph and creates or modifies non-dependent resources in parallel. This allows Terraform to build resources as efficiently as possible and gives you greater insight into your infrastructure.

»Change Automation

Terraform can apply complex changesets to your infrastructure with minimal human interaction. When you update configuration files, Terraform determines what changed and creates incremental execution plans that respect dependencies.

 

Use Cases

 

Heroku App Setup

Heroku is a popular PaaS for hosting web apps. Developers create an app, and then attach add-ons, such as a database, or email provider. One of the best features is the ability to elastically scale the number of dynos or workers. However, most non-trivial applications quickly need many add-ons and external services.

You can use Terraform to codify the setup required for a Heroku application, ensuring that all the required add-ons are available, but it can go even further: configuring DNSimple to set a CNAME, or setting up Cloudflare as a CDN for the app. Best of all, Terraform can do all of this in under 30 seconds without using a web interface.

»Multi-Tier Applications

A very common pattern is the N-tier architecture. The most common 2-tier architecture is a pool of web servers that use a database tier. Additional tiers get added for API servers, caching servers, routing meshes, etc. This pattern is used because the tiers can be scaled independently and provide a separation of concerns.

Terraform is an ideal tool for building and managing these infrastructures. You can group resources in each tier together, and Terraform will automatically handle the dependencies between each tier. For example, Terraform will ensure the database tier is available before provisioning the web servers and that the load balancers are connected to the web nodes. You can then use Terraform to easily scale each tier by modifying the count configuration value. Because resource creation and provisioning is codified and automated, elastically scaling with load becomes trivial.

»Self-Service Clusters

At a certain organizational size, it becomes very challenging for a centralized operations team to manage a large and growing infrastructure. Instead it becomes more attractive to make "self-serve" infrastructure, allowing product teams to manage their own infrastructure using tooling provided by the central operations team.

You can use Terraform configuration to codify the knowledge of how to build and scale a service. You can then share these configurations throughout your organization, enabling customer teams to use Terraform to manage their services.

»Software Demos

Modern software is increasingly networked and distributed. Although tools like Vagrant exist to build virtualized environments for demos, it is still very challenging to demo software on real infrastructure which more closely matches production environments.

Software writers can provide a Terraform configuration to create, provision and bootstrap a demo on cloud providers like AWS. This allows end users to easily demo the software on their own infrastructure, and even enables tweaking parameters like cluster size to more rigorously test tools at any scale.

»Disposable Environments

It is common practice to have both a production and staging or QA environment. These environments are smaller clones of their production counterpart, but are used to test new applications before releasing in production. As the production environment grows larger and more complex, it becomes increasingly onerous to maintain an up-to-date staging environment.

Using Terraform, the production environment can be codified and then shared with staging, QA or dev. These configurations can be used to rapidly spin up new environments to test in, and then be easily disposed of. Terraform can help tame the difficulty of maintaining parallel environments, and makes it practical to elastically create and destroy them.

»Software Defined Networking

Software Defined Networking (SDN) is becoming increasingly prevalent in the datacenter, as it provides more control to operators and developers and allows the network to better support the applications running on top. Most SDN implementations have a control layer and infrastructure layer.

You can use Terraform to codify the configuration for software defined networks. Terraform can then use this configuration to automatically set up and modify settings by interfacing with the control layer. This allows the configuration to be versioned and changes to be automated. For example, you can use Terraform to configure AWS VPC.

»Resource Schedulers

In large-scale infrastructures, static assignment of applications to machines becomes increasingly challenging. To solve that problem, there are a number of schedulers like Borg, Mesos, YARN, and Kubernetes. These can be used to dynamically schedule Docker containers, Hadoop, Spark, and many other software tools.

Terraform is not limited to physical providers like AWS. Resource schedulers can be treated as a provider, enabling Terraform to request resources from them. This allows Terraform to be used in layers: to setup the physical infrastructure running the schedulers as well as provisioning onto the scheduled grid.

»Multi-Cloud Deployment

It's often attractive to spread infrastructure across multiple clouds to increase fault-tolerance. By using only a single region or cloud provider, fault tolerance is limited by the availability of that provider. Multi-cloud deployment allows for more graceful recovery of the loss of a region or entire provider.

Realizing multi-cloud deployments can be very challenging as many existing tools for infrastructure management are cloud-specific. Terraform is cloud-agnostic and allows a single configuration to be used to manage multiple providers, and to even handle cross-cloud dependencies. This simplifies management and orchestration, helping operators build large-scale multi-cloud infrastructures.

Introduction to Infrastructure as Code with Terraform

• 3 MIN

• PRODUCTS USED

• This tutorial also appears in: Azure, Associate Tutorials, Docker, GCP and OCI.

0:19

2:40

Infrastructure as code (IaC) tools allow you to manage infrastructure with configuration files rather than through a graphical user interface. IaC allows you to build, change, and manage your infrastructure in a safe, consistent, and repeatable way by defining resource configurations that you can version, reuse, and share.

Terraform is HashiCorp’s infrastructure as code tool. It lets you define resources and infrastructure in human-readable, declarative configuration files, and manages your infrastructure’s lifecycle. Using Terraform has several advantages over manually managing your infrastructure:

• Terraform can manage infrastructure on multiple cloud platforms.

• The human-readable configuration language helps you write infrastructure code quickly.

• Terraform's state allows you to track resource changes throughout your deployments.

• You can commit your configurations to version control to safely collaborate on infrastructure.

»Manage any infrastructure

Terraform plugins called providers let Terraform interact with cloud platforms and other services via their application programming interfaces (APIs). HashiCorp and the Terraform community have written over 1,000 providers to manage resources on Amazon Web Services (AWS), Azure, Google Cloud Platform (GCP), Kubernetes, Helm, GitHub, Splunk, and DataDog, just to name a few. Find providers for many of the platforms and services you already use in the Terraform Registry. If you don't find the provider you're looking for, you can write your own.

»Standardize your deployment workflow

Providers define individual units of infrastructure, for example compute instances or private networks, as resources. You can compose resources from different providers into reusable Terraform configurations called modules, and manage them with a consistent language and workflow.

Terraform’s configuration language is declarative, meaning that it describes the desired end-state for your infrastructure, in contrast to procedural programming languages that require step-by-step instructions to perform tasks. Terraform providers automatically calculate dependencies between resources to create or destroy them in the correct order.

To deploy infrastructure with Terraform:

• Scope - Identify the infrastructure for your project.

• Author - Write the configuration for your infrastructure.

• Initialize - Install the plugins Terraform needs to manage the infrastructure.

• Plan - Preview the changes Terraform will make to match your configuration.

• Apply - Make the planned changes.

»Track your infrastructure

Terraform keeps track of your real infrastructure in a state file, which acts as a source of truth for your environment. Terraform uses the state file to determine the changes to make to your infrastructure so that it will match your configuration.

»Collaborate

Terraform allows you to collaborate on your infrastructure with its remote state backends. When you use Terraform Cloud (free for up to five users), you can securely share your state with your teammates, provide a stable environment for Terraform to run in, and prevent race conditions when multiple people make configuration changes at once.

You can also connect Terraform Cloud to version control systems (VCSs) like GitHub, GitLab, and others, allowing it to automatically propose infrastructure changes when you commit configuration changes to VCS. This lets you manage changes to your infrastructure through version control, as you would with application code.

»Next steps

Now that you are familiar with the core concepts of infrastructure as code and Terraform, you are ready to write your own infrastructure configuration.

Continue to the next tutorial to install Terraform on your local machine and deploy a Docker container.