Recipes Concepts

Recipes are how resources are deployed. The generic term recipe is used because Radius uses existing Infrastructure as Code (IaC) solutions to perform the actual deployment of resources. Today, Radius supports deploying resources using both Terraform and Bicep, but Radius is designed to integrate with other IaC solutions in the future. Just as Resource Types can represent any resource, Recipes can deploy any resource supported by the IaC language. As long as there is a Terraform provider or Bicep extension, Radius can deploy that resource. In fact, if you have an existing Terraform configurations or Bicep templates, they can be used as Recipes with only minor changes.

The combination of Resource Types and Recipes remove the need for developers to have deep understanding of infrastructure they are deploying too. Additionally, Recipes enable platform engineers to enforce security, operational, and cost best practices by requiring resource deployments to be performed only via a configured Recipe.

How Recipes are executed

Recipes can be any new or existing Terraform configurations or Bicep template. When a resource is deployed via Radius, the Radius control plane (specifically the Application RP) cross-references the Resource Type and Environment to determine which Recipe to execute. It then executes the Terraform or Bicep binary within the Application RP container and passes the Recipe location as a command-line argument.

When executing the Terraform or Bicep binaries, Radius does several things:

1. Performs terraform init if needed and sets up a Terraform backend using a Kubernetes secret.
2. Sets up authentication to OCI registries where Bicep templates are stored using properties stored in the Environment resource.
3. Sets up authentication to Git repositories where Terraform configurations are stored using properties stored in the Environment resource.
4. Sets environment variables with AWS and Azure credentials. These are well-know environment variables used by AWS and Azure Terraform providers and Bicep.
5. Passes in a Terraform variable or Bicep parameter called context which is discussed in detail below.
6. Passes in any Recipe parameters set on the Environment as a Terraform variable or Bicep parameter.
7. Reads the result output and updates the resource in Radius (also discussed below).

Recipe context object and Recipe parameters

Radius automatically injects a context object when deploying resources. The context object is rich with contextual information about the Environment, Application, and the resource being deployed. This includes:

• The Application name
• The Environment name as well as Kubernetes, AWS, and Azure details
• Parameters specified in the Environment definition
• The resource name and all of its properties
• All connected resources and their properties

In addition to context, platform engineers can specify Recipe parameters in the Environment definition. These Recipe parameters are then set as Terraform variables or Bicep parameters.

By using the context object and Recipe parameters, Recipes have all the information needed to deploy the actual resource in the target location. this significantly reduces the amount of information needed from developers.

Recipe outputs

Once the Recipe has been executed, Radius looks for a result output. The result output should contain output values for each of the read-only properties defined in the Resource Type so that Radius can set the read-only properties for use in the application definition. The result output should also include the resources created so Radius can track dependencies and manage deletions.

Next step: Read about Environments concepts