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Managing Infrastructure at Scale | Spacelift Blog

Securing your infrastructure is critical for the success of your business. Failure to take security seriously can result in major damage including fines, loss of customer confidence, or the inability to carry out crucial business functions. The growth of Infrastructure as Code tools and CI/CD systems has allowed developers to integrate infrastructure management into our typical development workflows, improving quality and delivery speed.
<div>At the same time, in order to manage your infrastructure, the CI/CD system used needs access to sensitive credentials. At Spacelift, we aim to give our users the maximum balance between flexibility and security. Because of this, we provide multiple options for connecting your Azure subscriptions to Azure, including setting static credentials, using our fully managed integration, as well as utilizing private workers to avoid sharing credentials at all.</div>
In this post we wanted to give you an overview of how the <a href="https://docs.spacelift.io/integrations/cloud-providers/azure#spacelift-managed-integration" target="_blank" rel="noopener">Spacelift Azure integration</a> works from a technical perspective, as well as discuss some of the issues we encountered and solved while designing and developing it. As a CI/CD system, we do quite a lot of work to integrate with other systems that our users use. Occasionally, like in the case of Azure, things get non-trivial. If you’re keen to learn more, read on, no Azure knowledge required!

Let’s start with a quick description of how our <a href="https://docs.spacelift.io/integrations/cloud-providers" target="_blank" rel="noopener">cloud integrations</a> work. The overall workflow is very simple, and looks something like this:

Building a Secure CI/CD Integration with Azure

Breaking the requirements down, we need to be able to get management credentials for a user’s cloud provider account and pass them to Terraform via environment variables, at which point Terraform can run an apply with access to the customer’s infrastructure.
Note: For simplicity this post uses Terraform in all its examples, but this overall approach also applies to the other tools that we support, for example, <a href="https://docs.spacelift.io/vendors/pulumi" target="_blank" rel="noopener">Pulumi</a>.
The concept behind the Azure integration was to provide a similar experience to our <a href="https://docs.spacelift.io/integrations/cloud-providers/aws" target="_blank" rel="noopener">AWS</a> and <a href="https://docs.spacelift.io/integrations/cloud-providers/gcp" target="_blank" rel="noopener">GCP</a> integrations, but for our Azure customers. The following diagram shows a simplified outline of how the AWS integration works:

10-2

AWS provides the ability to temporarily <a href="https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html" target="_blank" rel="nofollow noopener">assume a role</a> in another AWS account. This allows our users to create a role in IAM with any permissions they might want to give Spacelift. They can then set up a trust relationship for this role with our AWS account, which will allow our AWS account to assume the role. Role assumption provides us with raw AWS credentials and works seamlessly with any AWS tooling, including the Terraform AWS provider. It additionally allows us to specify the validity duration, so each run can get its own credentials which are constrained to a short period of time. 
Although Azure doesn’t have the same capability, it provides another approach called Azure Active Directory Applications, that allow service accounts to be created. Azure AD Applications are the resources that allow Spacelift to seamlessly manage access to a customer’s Azure resources.

It’s worth explaining a few pieces of terminology that are used throughout the rest of this post:
<ul>
<li style="font-weight: 400;" aria-level="1"><a href="https://azure.microsoft.com/en-gb/services/active-directory/" target="_blank" rel="nofollow noopener">Azure Active Directory</a> (Azure AD) &#8211; the identity and access management component of Azure.</li>
<li style="font-weight: 400;" aria-level="1">Directory / tenant &#8211; an individual instance of Azure AD owned by a company or individual.</li>
<li style="font-weight: 400;" aria-level="1">Subscription &#8211; the container for any Azure compute resources. This roughly corresponds to an AWS Account. A subscription is linked to a single Azure AD tenant, but multiple subscriptions can be linked to the same tenant.</li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.microsoft.com/en-us/azure/active-directory/develop/active-directory-how-applications-are-added" target="_blank" rel="nofollow noopener">Azure AD Application</a> &#8211; a way of creating external integrations with Azure AD.</li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/what-is-application-management" target="_blank" rel="nofollow noopener">Enterprise Application</a> &#8211; an instance of an Azure AD application that has been installed in another user’s Azure AD tenant.</li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.microsoft.com/en-us/azure/active-directory/develop/app-objects-and-service-principals#service-principal-object" target="_blank" rel="nofollow noopener">Service Principal</a> &#8211; a service account that is automatically created when an Azure AD application is installed. This can be used to grant permissions that allow the application to manage Azure resources.</li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.microsoft.com/en-us/graph/" target="_blank" rel="nofollow noopener">Microsoft Graph API</a> &#8211; the main API for managing Azure AD resources.</li>
</ul>

We set a number of goals for the integration:
<ul>
<li style="font-weight: 400;" aria-level="1">Making it really easy for customers to manage Azure infrastructure using Spacelift.</li>
<li style="font-weight: 400;" aria-level="1">Automatic handling of credential rotation so that customers don&#8217;t have to deal with this themselves, or use very long-lived credentials to avoid it entirely.</li>
<li style="font-weight: 400;" aria-level="1">Providing a mechanism for customers to configure granular permissions in Azure for different stacks, or different types of runs (e.g. PRs vs Tracked Runs).</li>
</ul>
&nbsp;

Initially, our idea was to create a single <a href="https://docs.microsoft.com/en-us/azure/active-directory/develop/single-and-multi-tenant-apps" target="_blank" rel="nofollow noopener">multi-tenant AD Application</a>:

The idea was that we would generate an Access Token that could only be used for a specific customer directory, and pass that token to the Terraform Azure RM provider during runs. In the end, we had to revise our approach because of the following issues:
<ul>
<li style="font-weight: 400;" aria-level="1">The <a href="https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs" target="_blank" rel="nofollow noopener">Terraform Azure RM provider</a> doesn&#8217;t support authentication via an Access Token. Instead, you have to supply the underlying credentials for the account &#8211; either a Client Secret or a Client Certificate. In our case, that would have meant passing the credentials for our own multi-tenant application to Spacelift runs. Since that application would have been installed in the Azure AD tenants of any Spacelift user who had setup the integration, this could have allowed users to access other user’s Azure accounts.</li>
<li style="font-weight: 400;" aria-level="1">The integration would have been less flexible. Using a single multi-tenant AD application would have prevented customers from creating more than one Azure integration per Active Directory tenant. The ability to create multiple integrations per tenant is useful because it allows different Azure permissions to be applied to each integration.</li>
</ul>

After days of brainstorming on an alternative approach, we came up with a new architecture. We could programmatically generate a new Azure AD Application on our side for each Azure Integration created by Spacelift users. This way, having access to the credentials for an Azure AD Application would only lead to having access to a single Azure AD Tenant on a user’s side. This approach allows Client Secrets to be passed to Spacelift runs without fear of inter-user permission leakage. The final design ended up as shown in the following diagram:

Applications are installed into a customer’s Active Directory tenant via a process called <a href="https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/grant-admin-consent" target="_blank" rel="nofollow noopener">Admin Consent</a>. After admin consent has been completed, a Service Principal is created in the user’s Azure Active Directory to which the user can grant permissions. This allows users to decide the exact level of access that Spacelift has to their resources.

The next issue we faced was related to generating credentials for a run. As described in the <a href="https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/guides/service_principal_client_secret" target="_blank" rel="nofollow noopener">provider documentation</a>, the Azure RM provider can be configured by setting certain environment variables. Initially, we took a basic approach of attempting to generate credentials during a Spacelift run. This is what we do for our AWS and GCP integrations, so we weren’t expecting major issues. The steps taken looked something like this:
<ol>
<li style="font-weight: 400;" aria-level="1">Run triggered.</li>
<li style="font-weight: 400;" aria-level="1">Generate a new Client Secret with a short expiry time.</li>
<li style="font-weight: 400;" aria-level="1">Populate the required environment variables.</li>
<li style="font-weight: 400;" aria-level="1">Execute terraform.</li>
</ol>
This seemed to work&#8230; but only some of the time.
While testing the integration, strange things were happening. As an example, the planning phase for a run would succeed, but the apply would fail with a permissions error from Azure. After investigating, we came to the conclusion that this was being caused by <a href="https://docs.microsoft.com/en-us/azure/active-directory/fundamentals/active-directory-architecture" target="_blank" rel="nofollow noopener">eventual consistency</a> in Azure AD.
You can visualize the problem using the following diagram (note: this is just an illustration, and is not meant to be completely accurate):

In the example above, step 2 may succeed or fail depending on whether the secret has managed to replicate to the Azure AD server that its request is routed to. Initially, we attempted to test whether or not the secret was usable by making an API request, and retrying until the request succeeded using an exponential backoff. What we soon realized was that even then, subsequent requests could be routed to a different Azure AD instance, which still hasn’t received the new Client Secret, and potentially fail.
Even if it was possible to verify when the secret was fully replicated, waiting for replication to complete would have added a minimum of 30 seconds, and potentially another several minutes. Because of this, we decided to move credential generation and rotation out of the run flow, and into a scheduled task:

The scheduled task runs once per hour, generates secrets with an expiry of 24 hours, and attempts to generate a new secret for an integration roughly 2 hours before expiry of the old secret. This allows credential rotation while always keeping a valid secret.
When a new secret is generated, we use AWS’s <a href="https://aws.amazon.com/kms/" target="_blank" rel="nofollow noopener">Key Management Service</a> to encrypt it so that it is never stored in plaintext.
When a run is triggered, we try to find the secret for the integration with the most amount of time until expiry. We also avoid using new secrets until roughly 10 minutes after generation to avoid the eventual consistency issues caused by Azure AD&#8217;s architecture.
You can visualize the secret lifecycle using the following diagram:

In addition, when creating a new integration we immediately generate a secret. This helps to ensure that the secret will have successfully propagated within Azure AD by the time a run is triggered.

The last major issue we faced was figuring out how to implement credential rotation for our own management account. The integration itself uses an Azure AD Service Principal to manage customer AD Applications using the Microsoft Graph API. Because we run most of our own infrastructure in AWS, we didn&#8217;t have the option of using a <a href="https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/overview">Managed Service Identity</a>, meaning that we needed to handle credential rotation ourselves. In addition, our goal was to automate the process to avoid developers having to periodically perform a manual task, and to reduce the risk of forgetting to renew the credentials before expiry.
In the end, we decided to take the relatively simple approach of storing the certificate in Secrets Manager and writing a scheduled task to periodically check whether the certificate was ready to expire, similar to the approach we took for Client Secrets for the integration. If so the scheduled task generates a new certificate and uploads it to both Secrets Manager and Azure AD:

The parts of the system that need to use the client certificate for authentication periodically check for an updated certificate. As with the client secret rotation, we avoid using the new certificate for approximately 10 minutes to allow time for the certificate to propagate throughout Azure AD.
Similar to what happens with the integration client secrets, Secrets Manager uses AWS Key Management Service to encrypt the certificate at rest.

Hopefully, this post has given you a glimpse into the internals of Spacelift&#8217;s Azure integration, along with some of the problems we had to solve while implementing it. As you probably noticed, we’re willing to go to great lengths to ensure a secure and pleasant experience for our users. To find out more, take a look at our Azure integration documentation available at <a href="https://docs.spacelift.io/integrations/cloud-providers/azure" target="_blank" rel="noopener">Spacelift Documentation</a>.

Managing Azure Resources using Spacelift

How to Manage Active Directory Objects with Azure AD Provider for Terraform

Introducing the Spacelift Azure Integration!

In this post we wanted to give you an overview of how the Spacelift Azure integration works from a technical perspective, as well as discuss some of the issues we encountered and solved while designing and developing it.

2-1-1

How to Build a Secure CI/CD Integration with Azure

The introduction of Infrastructure as Code or IaC has transformed the way you can provision and deploy high-performance cloud-based IT infrastructures.
IaC tools, such as Terraform, have been integrated into DevOps toolchains, saving DevOps IaC teams from the excessive manual effort.
While these tools undoubtedly help accelerate building IT infrastructures, their limitations can impact DevOps’ ability to optimize and improve control of their IaC processes supporting future business needs.
In this article, you’ll learn about IT infrastructure limitations that IaC DevOps teams deal with on a daily basis and how Spacelift is able to get past them.

One of the most frequent challenges while using more generic IaC tools is the non-intuitive workflow driven by its reliance on pull requests. Some solutions offer multiple workspaces, but the result can be fragile and nondeterministic. 
Since there’s no concept of mapping projects to branches or tags, anyone commenting on an approved pull request can deploy arbitrary code to production, even if the approval was meant for a short-lived experimental environment.
Spacelift does not depend on pull requests. It is mostly driven by push and tag events, so building a sophisticated Git flow is much easier. Spacelift reports the outcome of its jobs as commit status checks, allowing you to block merging the code on a failing Spacelift check.
Triggering a run can be customized using <a href="https://docs.spacelift.io/concepts/policy/git-push-policy" target="_blank" rel="noopener">Git push policies</a>. Thanks to that, Spacelift can provide the same level of comfort and security to teams using one project per repository and those using mono repo with hundreds of interdependent projects. You can read more about our approach to VCS integration <a href="https://docs.spacelift.io/integrations/github#tracked-branches" target="_blank" rel="noopener">here</a>.

The majority of generic tools don’t offer access control models but rely on comments on pull requests to drive infrastructure deployments. While it is usually fine when a single repository drives a single Terraform project, it becomes a huge liability for more complex scenarios.
Spacelift ships with a sophisticated mechanism allowing administrators to declare <a href="https://docs.spacelift.io/concepts/policy/login-policy" target="_blank" rel="noopener">who can log in</a> (and under what circumstances) and what their <a href="https://docs.spacelift.io/concepts/policy/stack-access-policy" target="_blank" rel="noopener">level of access</a> to each of the managed projects should be. Even our <a href="https://docs.spacelift.io/integrations/slack" target="_blank" rel="noopener">Slack integration</a> can be subject to policy controls, allowing an admin to grant access to a project <a href="https://docs.spacelift.io/integrations/slack#managing-access-to-stacks-with-policies" target="_blank" rel="noopener">based on Slack-specific data</a> (think team, channel, user, etc.).

One thing that’s not in scope for most IaC solutions is the way to ensure that your infrastructure is compliant with industry best practices and your company policies.
Spacelift puts policy-as-code in the center of its value proposition and builds a consistent, <a href="https://docs.spacelift.io/concepts/policy" target="_blank" rel="noopener">robust policy framework</a> on top of <a href="https://www.openpolicyagent.org/" target="_blank" rel="nofollow noopener">Open Policy Agent</a>. Apart from providing a comprehensive automated change review and ensuring compliance of your <a href="https://docs.spacelift.io/concepts/policy/terraform-plan-policy" target="_blank" rel="noopener">Terraform changes</a>, Spacelift uses the same approach to allow you to declare rules around the <a href="https://docs.spacelift.io/concepts/policy/login-policy" target="_blank" rel="noopener">account</a> and <a href="https://docs.spacelift.io/concepts/policy/stack-access-policy" target="_blank" rel="noopener">project access</a>, <a href="https://docs.spacelift.io/concepts/policy/git-push-policy" target="_blank" rel="noopener">handling push notifications</a>, <a href="https://docs.spacelift.io/concepts/policy/run-initialization-policy" target="_blank" rel="noopener">starting runs</a> and <a href="https://docs.spacelift.io/concepts/policy/task-run-policy" target="_blank" rel="noopener">triggering tasks</a>, and creating <a href="https://docs.spacelift.io/concepts/policy/trigger-policy" target="_blank" rel="noopener">relationships between projects</a>.

Handling interdependencies between projects has always been Terraform’s Achilles’ heel. The usual approach to this problem is adding another layer of abstraction in the form of a Terraform wrapper like <a href="https://terragrunt.gruntwork.io/" target="_blank" rel="nofollow noopener">Terragrunt</a>. But it’s only a partial solution as it breaks the problem into smaller chunks.
<a href="https://docs.spacelift.io/concepts/policy/trigger-policy" target="_blank" rel="noopener">Spacelift’s trigger policies</a> on the other hand provide a smart, declarative automation layer on top of vanilla Terraform. They allow you to plug into state changes of individual projects and declare dependencies that should be resolved, following the changes that have just been applied. Read more <a href="https://docs.spacelift.io/concepts/policy/trigger-policy" target="_blank" rel="noopener">here</a> to discover other exciting possibilities.

Another problem to solve externally when using some of the generic tools is authoring and maintaining reusable <a href="https://spacelift.io/blog/what-are-terraform-modules-and-how-do-they-work" target="_blank" rel="noopener">Terraform modules</a> for your organization. Terraform is flexible in allowing modules to come from <a href="https://www.terraform.io/docs/modules/sources.html" target="_blank" rel="nofollow noopener">various sources</a>, but ensuring confidential access, as well as testing and versioning, are left to you, the user.
Until now, the golden standard in that regard has been the <a href="https://www.terraform.io/docs/cloud/registry/index.html" target="_blank" rel="nofollow noopener">private module registry from HashiCorp</a>. But Spacelift offers much more. Far from being just a glorified package manager, Spacelift adds a <a href="https://docs.spacelift.io/concepts/modules" target="_blank" rel="noopener">full CI solution for Terraform modules</a>, out of the box and free of charge. You can thus ensure that your private modules are healthy before you distribute them to the rest of your organization.

If you manage a single or a handful of rarely changing projects, it’s likely that you just set your IaC up once and forget about it. But in a more dynamic environment, where microservices come and go, new environments proliferate and new product teams require their own Terraform workspaces. The need to configure it each and every time become a major nuisance, putting a lot of pressure on your DevOps team.
Enter Spacelift. In Spacelift, much of the configuration can be handled by the project owners themselves—you can add Terraform and/or <a href="https://docs.spacelift.io/concepts/environment" target="_blank" rel="noopener">environment variables</a> and mount files (even inject Terraform code!) programmatically or through the GUI without the need for administrative privileges or changing the central server configuration. For administrators, adding new projects requires minimal hassle since there’s no need to set up webhooks or change any YAML. And it can all be done programmatically using Terraform.

What comes as a pleasant surprise to users of generic CI tools, Spacelift entities such as stacks, contexts, modules or policies can be managed in a declarative way using your favorite infra-as-code tool (this rule applies also to their configuration). Yes, that’s right—<a href="https://docs.spacelift.io/integrations/terraform-provider" target="_blank" rel="noopener">Spacelift offers a Terraform provider</a> that allows you to programmatically manage the lifecycle of its own resources.
Administrative stacks get credential-less access to the subset of our <a href="https://docs.spacelift.io/integrations/api" target="_blank" rel="noopener">GraphQL API</a> that does not involve managing the actual infrastructure. For more sophisticated use cases, Spacelift allows you to generate API keys that are subject to the same access controls as normal users are, allowing you to create single-purpose tokens for restricted use by your internal scripts.

Generic IaC platforms do not provide any mechanisms to detect if your infrastructure is undergoing drift. Drift is a condition that represents the difference between the desired and the actual state of the infrastructure managed by your tool of choice &#8211; <a href="https://www.terraform.io/" target="_blank" rel="nofollow noopener">Terraform</a>, <a href="https://www.pulumi.com/" target="_blank" rel="nofollow noopener">Pulumi</a>, <a href="https://aws.amazon.com/cloudformation/" target="_blank" rel="nofollow noopener">CloudFormation</a> or another. Drift can be caused by either or a combination of changes directly introduced by external actors &#8211; either humans or machines (scripts) or via the dependency of your resources on external data sources. In any case, drift is not good.
Spacelift has got you covered here. You can configure periodic <a href="https://docs.spacelift.io/concepts/stack/drift-detection" target="_blank" rel="noopener">drift detection </a>to notify you whenever drift happens, and take immediate action. You can even go a step further with optional automatic <a href="https://docs.spacelift.io/concepts/stack/drift-detection#to-reconcile-or-not-to-reconcile" target="_blank" rel="noopener">reconciliation</a>, ensuring your infrastructure always resembles your Terraform configuration.

General-purpose CI/CD platforms provide little to no insight into resource utilization from either a real-time or historical perspective. Which resources are over-or underutilized? 
Developers need to be able to intimately understand the material they’re working with. With regards to infra-as-code, the most important part of this story is understanding the managed resources in-depth. Both from the current perspective and through being able to put each resource in its historical context.
The resources view in Spacelift gives you greater visibility into each and every resource. With this deep insight into resources, DevOps are able to gain an understanding of the lifecycle of each resource managed by Spacelift and document it, regardless of the technology used — <a href="https://www.terraform.io/" target="_blank" rel="nofollow noopener">Terraform</a>, <a href="https://github.com/gruntwork-io/terragrunt" target="_blank" rel="nofollow noopener">Terragrunt</a>, <a href="https://www.pulumi.com/" target="_blank" rel="nofollow noopener">Pulumi</a>, or <a href="https://aws.amazon.com/cloudformation/" target="_blank" rel="nofollow noopener">CloudFormation</a>.

Last but not least, Spacelift puts an emphasis on great user experience, offering a myriad of creature comforts. <a href="https://docs.spacelift.io/concepts/context" target="_blank" rel="noopener">Contexts</a> for example allow you to attach entire collections of configuration to individual stacks and modules. <a href="https://docs.spacelift.io/concepts/task" target="_blank" rel="noopener">Tasks</a> provide a powerful audited way of running one-off administrative commands on an initialized Terraform environment &#8211; subject to <a href="https://docs.spacelift.io/concepts/task" target="_blank" rel="noopener">their own policy constraints</a>. <a href="https://docs.spacelift.io/concepts/stack#stack-locking" target="_blank" rel="noopener">Stack locking</a> allows a single individual to take exclusive control over a stack to ensure that nobody is able to modify its state while crucial changes are being made.

Spacelift is an innovative and sophisticated SaaS product for Infrastructure as Code which helps IaC DevOps develop and deploy new infrastructures or changes quickly and with confidence.
Spacelift offers a unique set of IaC management capabilities:
<ol>
<li style="font-weight: 400;" aria-level="1">an intuitive, <a href="https://docs.spacelift.io/concepts/policy/git-push-policy" target="_blank" rel="noopener">versatile</a> and <a href="https://docs.spacelift.io/concepts/run#run-state-machine" target="_blank" rel="noopener">robust</a> workflow</li>
<li style="font-weight: 400;" aria-level="1">granular access controls on <a href="https://docs.spacelift.io/concepts/policy/login-policy" target="_blank" rel="noopener">account</a> and <a href="https://docs.spacelift.io/concepts/policy/stack-access-policy" target="_blank" rel="noopener">project</a> level that work well with an <a href="https://docs.spacelift.io/integrations/single-sign-on" target="_blank" rel="noopener">identity provider of your choice</a> (SSO)</li>
<li style="font-weight: 400;" aria-level="1">an <a href="https://docs.spacelift.io/concepts/policy/terraform-plan-policy" target="_blank" rel="noopener">automated code review</a> and <a href="https://docs.spacelift.io/concepts/policy/task-run-policy" target="_blank" rel="noopener">threat detection</a> </li>
<li style="font-weight: 400;" aria-level="1">the ability to <a href="https://docs.spacelift.io/concepts/policy/trigger-policy" target="_blank" rel="noopener">declare complex workflows</a> between projects across multiple repositories</li>
<li style="font-weight: 400;" aria-level="1">a <a href="https://docs.spacelift.io/concepts/modules" target="_blank" rel="noopener">built-in private module registry</a> with a full CI system for modules</li>
<li style="font-weight: 400;" aria-level="1">effortless setup and customization with <a href="https://docs.spacelift.io/concepts/environment" target="_blank" rel="noopener">per-project environment management</a> and <a href="https://docs.spacelift.io/integrations/docker" target="_blank" rel="noopener">Docker integration</a></li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.spacelift.io/integrations/terraform-provider" target="_blank" rel="noopener">programmatic configuration</a> using Terraform</li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.spacelift.io/concepts/stack/drift-detection" target="_blank" rel="noopener">drift detection </a></li>
<li style="font-weight: 400;" aria-level="1"><a href="https://docs.spacelift.io/concepts/resources" target="_blank" rel="noopener">resource visualization</a></li>
</ol>
… and a multitude of additional perks like <a href="https://docs.spacelift.io/concepts/context" target="_blank" rel="noopener">contexts</a>, <a href="https://docs.spacelift.io/concepts/task" target="_blank" rel="noopener">tasks</a> or <a href="https://docs.spacelift.io/concepts/stack#stack-locking" target="_blank" rel="noopener">stack locking</a>.

There are many ways of working with Terraform. Each way is different in terms of complexity and offers a different set of features. It is important to keep in mind that choosing one way or another should be based on business and technical requirements. Most often, there is no point in implementing an in-house solution as the cost and effort of building and maintaining it may exceed its potential benefits. It is much easier and more efficient to leverage platforms such as Spacelift to provide these features for you instead.

5 Ways to Manage Terraform at Scale

Terraform Functions, Expressions, Loops

Terraform vs. Ansible: Key Differences

Most often, there is no point in implementing an in-house solution as the cost and effort of building and maintaining it may exceed its potential benefits. It is much easier and more efficient to leverage ready-to-go platform to provide these features instead.

How a Specialized Management Solution Can Improve Your IaC

Learning Terraform can be easy. The HCL configuration language is simple enough to start with basic resource creation straight away. 
But—
Once the code that defines your infrastructure grows in complexity, maintainability, and dependency, an uphill battle can ensue. And that is why working out an efficient deployment workflow is crucial for further development.
In this article you will see five approaches to managing Terraform at scale, what their benefits and downsides are, and what problems they address.

A quick and easy way to start deploying resources using the Infrastructure as Code pattern is to use Terraform locally from the same machine you’re developing the code on. The only requirement is to have access to the target provider and an installed Terraform binary.
This approach makes it much easier to leverage commands related to day-to-day operations (such as state import, move, remove) or to get outputs than if doing it within the implementations where you have no direct access to the underlying provider.
You can also use all of the features of Terraform, such as remote state and state locking, to work with your teammates all-at-once. If you collaborate using a version control system and do not have continuous integration in place, but want to keep your code at a decent level of quality, there are tools to help you.
One of these is <a href="https://github.com/antonbabenko/pre-commit-terraform" target="_blank" rel="nofollow noopener">pre-commit-terraform</a> that will run a set of selected tools to lint the code you’re creating before you even commit it. Even if you have continuous integration available, it’s a handy way to avoid wasting time waiting for results from pull request status checks.
What are the drawbacks of this approach? Each action is manual and must be performed directly by the developer, which leads to several issues. 
In a situation where multiple people are working on the same codebase, you could often encounter a scenario such as this one:
Person A applies their changes to the environment and follows up with a pull request. At the same time, Person B would like to deploy their changes but is blocked as the codebase is not up-to-date with Person A’s changes. Applying the changes in this state would cause damage to the resources created in the previous deployment. When working in larger teams, this will often result in a lot of wasted time just waiting and rebasing on a codebase to apply the changes.
If you happen to write unit tests for <a href="https://spacelift.io/blog/what-are-terraform-modules-and-how-do-they-work" target="_blank" rel="noopener">Terraform modules</a> (and you should be), you’re sure to know they need to be executed manually from your computer. Running them every time you change something in your configuration can be tedious and time-consuming. If you do not yet write tests for your modules, you’d be well advised to start looking at <a href="https://docs.spacelift.io/vendors/terraform/module-registry#tests" target="_blank" rel="nofollow noopener">Spacelift modules tests</a> or <a href="https://terratest.gruntwork.io/docs/getting-started/quick-start/" target="_blank" rel="nofollow noopener">Terratest</a>.
Privileged access to an underlying vendor is required, which can easily result in a compromised environment. It’s much harder to keep restricted access within this model, as Terraform must be allowed to create, change, and destroy resources. The same rule applies to a scenario where access to private (internal) resources is required, e.g., every developer has to set up a VPN connection to interact with them.
Moreover, every person working with the codebase needs access to the Terraform state, which creates a security concern due to how Terraform state works. Even if you’re pulling sensitive data from an external system such as Vault, it will be stored within the state file in plaintext once used in a resource. A threat actor could simply run `terraform state pull` to access all the secrets!
Keeping all these issues in mind, let’s take a look at a more automated approach.

Implementing homegrown automation means incorporating Terraform workflow into your continuous integration / continuous deployment process. A specific example would need to directly tie to a CI/CD tool you are using, so let’s try to keep the example as generic as possible.
As the applying actor is the CI/CD system, the hard requirement of privileged access for developers is gone. You can grant this type of access to the execution layer while developers keep read-only permissions. This is true for private (internal) resources, and if your code is being executed on an agent that resides within the target infrastructure with the proper permissions having been set. In a model where everything has to go through the CI/CD pipeline, visibility of changes is improved as the system logs produced during the operation execution are available in real-time. 
Linting, compliance checks, and automated unit tests can be moved to pull request status checks, and it’s up to you to configure these steps of the pipeline.
But—
If your CI/CD is executing jobs concurrently, you will end up with race conditions causing pull requests to fail non-deterministically. 
It is not difficult to imagine a situation where two operators open a pull request within several seconds of one another. The pipeline gets triggered immediately for both, and one pull request will be marked as successful, while the other will be marked as failed. This situation will definitely happen if you are using state locking (it is a best practice and you really should be using it).
The explanation is simple: the first pull request has locked the state and therefore the second one could not, so it failed. This issue can be resolved by configuring queued runs, where only one pipeline can run at a time. However, this is not so simple with some CI/CD products.
The biggest issue and concern with this approach is the effort you have to put in to build a complete pipeline. If you consider requirements such as:
<ul>
<li style="font-weight: 400;" aria-level="1">planning on pull requests</li>
<li style="font-weight: 400;" aria-level="1">linting</li>
<li style="font-weight: 400;" aria-level="1">unit tests</li>
<li style="font-weight: 400;" aria-level="1">compliance checks</li>
<li style="font-weight: 400;" aria-level="1">applying once merged</li>
<li style="font-weight: 400;" aria-level="1">periodical drift detection</li>
<li style="font-weight: 400;" aria-level="1">registry for all your versioned modules</li>
<li style="font-weight: 400;" aria-level="1">modules sharing across different parts of the organization</li>
<li style="font-weight: 400;" aria-level="1">shared variable contexts/reusable values</li>
</ul>
It might be tempting to implement solutions for those requirements by yourself. However, taking into account the time and effort required for doing it, you might want to take a look at alternatives, such as open-source tools.

One of the most popular open-source tools to use with Terraform is Atlantis, which describes itself as “Terraform pull request automation”. You can read more about it here: <a href="https://spacelift.io/blog/post/alternative-to-atlantis" target="_blank" rel="noopener">Alternative to Atlantis</a>.

Terraform Cloud is an application provided by the company behind Terraform itself—HashiCorp. It is available for free for up to 5 users. Two plans are available for more users: “Team &amp; Governance” and “Business”. As the product is created by Terraform authors themselves, any new feature that makes it to Terraform will be quickly available within Terraform Cloud as well. Neat!
<h3>Advantages of Terraform Cloud</h3>
Advanced security compliance mechanisms available through Sentinel allow you to enforce organization standards even before the code actually ships and creates resources with the chosen provider context.
Another important feature is a module registry that acts as an artifact repository for all your modules. It can be compared to JFrog Artifactory, Sonatype Nexus, or other similar software. Having every module in a separate repository and versioning allows you to control code promotion in a granular fashion or quickly roll back to if it allows you to go back to the most recent version only, then we should use “the”, but if it lets you go back to some other earlier version then we should use “a” previous version. 
Having a centralized place to store all the pieces also enables you to quickly browse through available modules, their documentation, inputs, outputs, and used resources. It is a great single pane of glass in terms of module management. However, it can only be used within the same Terraform Cloud organization and cannot be shared. This might be troublesome for operations teams that base their separation on the organization level.
There’s also the remote execution backend, which is an exclusive feature for Terraform Cloud. It allows you to work with Terraform on your local computer as you would usually do, upload your local codebase, and run a plan against it. It is a very efficient way of quickly verifying if what you are working on is actually working.
<h3>Disadvantages of Terraform Cloud</h3>
Along with so many benefits, there are some drawbacks as well. Any linting or module unit tests need to be implemented inside your own continuous integration system. This requires an additional effort the development team has to make to sustain their code quality.
Another disadvantage is that you are not able to share common values across your workspaces. Imagine a situation where you share a common set of variables like cloud region or environment name. The only way to achieve something similar to shared context is to have a dedicated workspace that will output this information as an input for all remaining workspaces, although this would be more of a workaround than an actual solution.
Compliance as code is available via Sentinel, a framework created by HashiCorp. Having a built-in solution to develop policies is nice, but operators often already use Open Policy Agent (OPA) to define these within different areas of the infrastructure. This frequently ends up in a doubled effort as you need to create a similar policy in both frameworks.
The biggest shortcoming of Terraform Cloud is in my opinion the lack of periodical drift detection runs. Once something is applied and the codebase does not get updates, you will never be notified if anything has changed in comparison to the state within the repository. Scheduling a daily “plan” to verify if everything is up-to-date would be highly beneficial to keep the infrastructure as described programmatically.

And here we are. You can compare Spacelift directly to Terraform Cloud. They share a lot of functionality with each other in terms of the actual deployment execution, but also in the area of compliance.
While Terraform Cloud uses Sentinel (the HashiCorp approach to implementation for compliance as code), Spacelift leverages Open Policy Agent. It is beneficial to have a similar way of working with policies for companies that already incorporate OPA in their workflow (e.g., for Kubernetes). As there is no need to learn another syntax, operators can focus their efforts on providing compliance, instead of learning yet another tool.
Spacelift also allows you to automate your workflow even further. By having a built-in continuous integration for modules, you can shift your linters or unit tests really quickly into one place dedicated to Terraform. It helps you reduce the effort required to implement integration workflow by letting you utilize a solution that you are already using.
Sometimes you need to work with a Terraform state directly to import something, for example. In scenarios where you are leveraging Terraform Cloud, it is often impossible to do this without accessing the provider yourself. In contrast, Spacelift gives you the ability to run literally any command within the context of a particular codebase via tasks. This way, you do not need to grant any additional permissions to import, move, or remove resources directly.
By utilizing contexts, you can simply share anything you like across multiple stacks—whether it is a set of environment variables or a file. This is something that becomes much more valuable once your codebase complexity increases.
As mentioned in the previous paragraph, drift detection is something that becomes much more important once your infrastructure grows. With Spacelift, it is possible to schedule a periodic drift detection on any stack. Going even further, you can enable automated remediation if any changes are found compared to what you have in your codebase.

There are many ways of working with Terraform. Each way is different in terms of complexity, and has a different set of features. It is important to keep in mind that choosing one way or another should be based on business and technical requirements. Most times, there is no point in implementing an in-house solution as the cost and effort of building and maintaining it may often exceed its potential benefits. It is much easier and quicker to leverage platforms such as Spacelift to provide these features for you instead.

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