Bicep vs Terraform: Choosing the Best IaC Tool for Azure

Infrastructure as Code (IaC) is a seriously useful way to manage your cloud environment. In the same way you code applications, you can use it to set up infrastructure.

And the two heavyweights that dominate Azure IaC conversations are Bicep vs Terraform.

Both tools have their merits, and the right choice will depend on your future ambitions and current environment. But all decisions have to start somewhere, so we’ve put together a quick guide on deciding which one might be best for your organisation.

Infrastructure as Code transforms how we provision and manage cloud resources by treating infrastructure configuration as software code. Rather than clicking through portals or running ad-hoc scripts, IaC brings version control, repeatability, and consistency to infrastructure deployment.

We’ve covered why you should be using Infrastructure as Code before, and the key point stands: it brings massively useful automation and standardisation to infrastructure management.

And yes, while ‘ClickOps’ certainly has its place, particularly for exploration and learning, production environments deserve the structure that IaC provides.

What is Terraform?

Terraform, created by HashiCorp, has become synonymous with multi-cloud IaC. It’s a declarative tool that uses its own domain-specific language (HCL – HashiCorp Configuration Language) to describe infrastructure across virtually any cloud provider or service that offers an API.

Terraform has an extensive provider ecosystem. With thousands of providers available, Terraform can manage resources in Azure, AWS, Google Cloud, and even SaaS platforms like GitHub or Datadog. It’s this flexibility that has made it a favourite amongst organisations with multi-cloud strategies or those that want to avoid vendor lock-in.

For those new to Terraform in an Azure context, we’ve created a guide on mastering the basics of Terraform and Infrastructure as Code in Azure.

What is Bicep?

Bicep is Microsoft’s answer to the complexity of ARM (Azure Resource Manager) templates. Launched in 2020, Bicep is a domain-specific language that transpiles to ARM JSON, offering a cleaner, more concise syntax whilst keeping full compatibility with Azure’s native deployment engine.

Bicep is ARM templates’ younger sibling—it does everything ARM templates do, but with a syntax that won’t make your eyes water. It’s Azure-native by design, which means it supports every Azure resource type and API version from day one. No waiting for provider updates or dealing with version mismatches.

Syntax and learning curve

Bicep’s syntax is notably cleaner and more intuitive than both ARM templates and (arguably) Terraform’s HCL. It uses a more natural style that many find easier to read and write. The learning curve for Bicep is generally a bit gentler, especially for those that already know Azure well.

Terraform’s HCL, while it’s more verbose, does have consistency across all providers. Once you learn HCL, you can apply that knowledge to any cloud or service Terraform supports.

This consistency is definitely a plus for teams working across multiple platforms.

State management approaches

Here’s where these tools fundamentally differ. Terraform keeps a state file that tracks the current state of your infrastructure. This state file is crucial for Terraform’s operation, but it needs careful management. It needs to be stored securely, shared amongst team members, and protected from corruption.

Bicep, being Azure-native, doesn’t maintain its own state file. Instead, it relies on Azure Resource Manager’s built-in state tracking. This means you don’t have to worry about state file management, but also that you lose some of Terraform’s advanced capabilities for state manipulation.

Module systems

Both tools support modular design: essential for working with large infrastructure deployments.

Terraform’s module system is mature and well-documented, with a public registry of community modules. (We’ve detailed how to create Terraform modules in Azure for those interested in this approach.)

Bicep modules are simpler to create and use, with native support for module registries in Azure Container Registry. The syntax for calling modules feels more natural in Bicep, though the ecosystem of pre-built modules is still growing.

Testing capabilities

Terraform’s testing story has matured significantly, with tools like Terratest enabling comprehensive infrastructure testing. The ecosystem provides various linting, security scanning, and policy-as-code tools.

Bicep’s testing capabilities are evolving rapidly. The Bicep linter provides excellent real-time feedback, and the recent additions of deployment stacks and what-if operations enhance the testing experience. However, the third-party testing ecosystem isn’t as mature as Terraform’s.

Terraform strengths and limitations

Terraform’s multi-cloud DNA and mature ecosystem make it a powerhouse for complex infrastructure scenarios.

Strengths:

• Multi-cloud flexibility: Manage Azure, AWS, Google Cloud, and more from a single tool

• Mature ecosystem: Extensive community, modules, and third-party tools

• Advanced state manipulation: Import existing resources, move resources between states, and perform complex refactoring

• Provider diversity: Manage not just cloud infrastructure but also SaaS configurations, monitoring, and more

Then again, great power comes with great complexity. Terraform demands careful attention to state management and versioning.

Limitations:

• State file complexity: Requires careful management, especially in team environments

• Provider lag: New Azure features may take time to appear in the Azure provider

• Learning curve: More concepts to master (providers, state, backends, workspaces)

• Version management: Keeping provider versions aligned across teams can be challenging

Bicep strengths and limitations

Purpose-built for Azure, Bicep gives you a streamlined experience that feels like it was designed by people who actually use Azure (because it was).

Strengths:

• Azure-native: Immediate support for all Azure features and API versions

• No state file management: Leverages Azure’s built-in state tracking

• Cleaner syntax: More readable and writable than ARM templates or HCL

• Tight Azure integration: Native support for Key Vault references, managed identities, and Azure-specific features

• Simplified tooling: Fewer moving parts to manage

But Bicep’s laser focus on Azure means accepting some trade-offs in flexibility and ecosystem maturity.

Limitations:

• Azure-only: No support for other clouds or services

• Younger ecosystem: Fewer community modules and third-party tools

• Limited state manipulation: Can’t easily import existing resources or perform complex state operations

• Deployment scope: Some limitations around cross-subscription or cross-tenant deployments

Working with Azure

When it comes to Azure integration, Bicep has the home advantage. It speaks Azure’s native language, supports every Azure feature immediately upon release, and integrates nicely with Azure DevOps, GitHub Actions for Azure, and the Azure CLI. There’s no translation layer: what you write in Bicep directly becomes ARM JSON.

Terraform’s Azure providers are comprehensive and well-maintained, but there’s usually a slight delay between Azure releasing a feature and it appearing in the provider. That said, Terraform offers powerful features like data sources for querying existing resources and the ability to mix Azure resources with other providers in a single configuration. (For teams looking to migrate existing infrastructure, we’ve covered how to import Azure resources into Terraform.)

Authentication is simpler with Bicep—if you can deploy to Azure, you can use Bicep. Terraform does need you to configure the Azure provider with appropriate credentials, which adds a small but notable setup step.

Beyond Azure

This is a simple part of the comparison: Terraform is a really good option for multi-cloud scenarios, while Bicep just doesn’t play outside Azure at all.

Terraform can orchestrate resources across multiple clouds and services in a single configuration. Need to provision Azure resources that depend on AWS S3 buckets? Or configure monitoring in Datadog alongside your Azure deployment? Terraform is the one for you.

Bicep’s Azure-only focus isn’t necessarily a limitation; it’s more a design choice. As it’s focusing solely on Azure, Bicep can provide a more Azure-optimised experience without the abstractions needed for multi-cloud support.

When to choose Bicep

As we’ve seen, Bicep is the clear choice if you’re big on Azure and want to keep things straightforward.

• Azure-exclusive environments: If you’re all-in on Azure with no plans to diversify, Bicep’s native integration makes for a smoother experience.

• Transitioning from ARM templates: Teams already using ARM templates will find Bicep a natural evolution. Your existing ARM knowledge translates directly, and you can even decompile ARM templates to Bicep.

• Rapid Azure adoption: When you need to use the latest Azure features as soon as they’re released, you can make it happen with Bicep.

• Simplified operations: Smaller teams (or those new to IaC) often appreciate Bicep’s reduced operational overhead. There’s no state files to manage and no provider versions to coordinate.

• Azure-native workflows: If you’re heavily invested in Azure DevOps, Azure Blueprints, or Azure Policy, Bicep integrates more naturally with these services.

When to choose Terraform

Terraform is great for going beyond Azure’s borders and running more complex architectures.

• Multi-cloud strategies: Orgs using multiple cloud providers (or thinking of doing so in the future) benefit from Terraform’s unified approach.

• Existing Terraform expertise: If your team already knows Terraform from other projects, using that expertise within Azure makes sense. Companies with established Terraform workflows, like policy as code or automated testing, can extend these to Azure easily.

• Complex state operations: Scenarios needing sophisticated state manipulation favour Terraform (e.g. importing existing infrastructure or splitting configurations).

• Third-party service integration: When your infrastructure spans beyond pure cloud resources to include SaaS platforms, CDNs, or DNS providers, Terraform’s provider ecosystem is unmatched.

For a broader perspective on choosing the right IaC tool for Azure, including other options like Powershell, take a look at our guide to selecting the right IaC tool for Azure.

IaC can be a game-changer, whichever flavour you choose, bringing consistency, reliability, and scale to your cloud operations.

Hopefully, this guide has given you a better idea of the nuances between the two options above. When making the decision, you’ll obviously have to take into account the unique nature of your environment, but these general ideas should help steer you in the right direction.

At Synextra, we’re here to help you navigate the world of cloud infrastructure. Whether you’re Team Bicep, Team Terraform, or still deciding, we’d love to help you make the most of it. If you’d like to uncover the true potential of a cloud-powered business, talk to us today.