Add HowTo tutorial to configure Terraform Custom Provider

.github/config/en-custom.txt

@@ -1253,3 +1253,7 @@ envSecrets
 RecipeConfigPropertiesEnvSecrets
 ProviderConfigPropertiesSecrets
 SecretReference
+cyrilgdn
+secretStore
+postgreSQL
+postgres

docs/content/guides/recipes/terraform/howto-custom-provider/index.md

@@ -0,0 +1,88 @@
+---
+type: docs
+title: "How-To: Configure custom Terraform Providers"
+linkTitle: "Custom Terraform Providers"
+description: "Learn how to setup your Radius environment with custom Terraform Providers and deploy recipes."
+weight: 500
+categories: "How-To"
+aliases  : ["/guides/recipes/terraform/howto-custom-provider"]
+tags: ["recipes", "terraform"]
+---
+
+This how-to guide will describe how to:
+
+- Configure a custom [Terraform provider](https://registry.terraform.io/browse/providers) in a Radius environment.
+- Configure credentials to authenticate into the Terraform provider.
+- Consume the terraform modules from a custom Terraform provider and use it in a Terraform recipe.
+
+In this example we're going to configure a [PostgreSQL Terraform provider](https://registry.terraform.io/providers/cyrilgdn/postgresql/latest/docs) in a Radius environment and deploy a recipe.  
+
+### Prerequisites
+
+Before you get started, you'll need to make sure you have the following tools and resources:
+
+- [rad CLI]({{< ref "installation#step-1-install-the-rad-cli" >}})
+- [Radius Bicep VSCode extension]({{< ref "installation#step-2-install-the-vs-code-extension" >}})
+- [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/)
+- [Radius initialized with `rad init`]({{< ref howto-environment >}})
+- [Recipes overview]({{< ref "/guides/recipes/overview" >}})
+
+## Step 1: Define a secretStore resource for the custom provider
+
+Configure a [Radius Secret Store]({{< ref "/guides/author-apps/secrets/overview" >}}) with any sensitive information needed as input configuration for the custom Terraform Provider. Define the namespace for the cluster that will contain your [Kubernetes Secret](https://kubernetes.io/docs/concepts/configuration/secret/) with the `resource` property. 
+
+> While this example shows a Radius-managed secret store where Radius creates the underlying secrets infrastructure, you can also bring your own existing secrets. Refer to the [secrets documentation]({{< ref "/guides/author-apps/secrets/overview" >}}) for more information.
+
+Create a Bicep file `env.bicep` with the secretStore resource:
+
+{{< rad file="snippets/env.bicep" embed=true marker="//SECRETSTORE" >}}
+
+> In this example, we're creating a secret with keys `username` and `password` as sensitive data required to authenticate into the Terraform Provider `cyrilgdn/postgresql`.
+
+## Step 2: Configure Terraform Provider
+
+`recipeConfig/terraform/providers` allows you to setup configurations for one or multiple Terraform Providers. For more information refer to the [Radius Environment schema]({{< ref environment-schema >}}) page.
+
+In your `env.bicep` file add an Environment resource, along with Recipe configuration which leverages properties from the previously defined secret store.
+In this example you're also passing in `host` as an environment variable to highlight use cases where, depending on provider configuration requirements, users can pass environment variables to the Terraform runtime.
+
+{{< rad file="snippets/env.bicep" embed=true marker="//ENV" >}}
+
+## Step 3: Define a Terraform Recipe
+
+Create a Terraform recipe which deploys a postgreSQL database instance using custom Terraform provider `cyrilgdn/postgresql`  
+
+{{< rad file="snippets/postgres.tf" embed=true marker="//ENV" >}}
+
+## Step 4: Add a Terraform Recipe to the environment
+
+Update your Environment with the Terraform Recipe. 
+
+{{< rad file="snippets/env-complete.bicep" embed=true marker="//ENV" markdownConfig="{linenos=table,hl_lines=[\"22-30\"],linenostart=30,lineNos=false}" >}}
+
+## Step 5: Deploy your Radius Environment
+
+Deploy your new Radius Environment passing in values for `username` and `password` needed to authenticate into the provider. The superuser for this PostgreSQL recipe is `postgres` which is the expected input for `username`:
+
+```bash
+rad deploy ./env.bicep -p username=****** -p password=******
+```
+
+## Done
+
+Your Radius Environment is now configured with a custom Terraform provider which you can use to deploy Radius Terraform recipes. For more information on Radius Recipes visit the [Recipes overview page]({{< ref "/guides/recipes/overview" >}}).
+
+## Cleanup
+
+You can delete the Radius Environment by running the following command:
+
+```bash
+rad env delete my-env
+```
+
+## Further reading
+
+- [Recipes overview]({{< ref "/guides/recipes/overview" >}})
+- [Radius Environments]({{< ref "/guides/deploy-apps/environments/overview" >}})
+- [`rad recipe CLI reference`]({{< ref rad_recipe >}})
+- [`rad env CLI reference`]({{< ref rad_env >}})

docs/content/guides/recipes/terraform/howto-custom-provider/snippets/env-complete.bicep

@@ -0,0 +1,72 @@
+//SECRETSTORE
+import radius as radius
+
+@description('username for postgres db')
+@secure()
+param username string
+
+@description('password for postgres db')
+@secure()
+param password string
+
+resource pgsSecretStore 'Applications.Core/secretStores@2023-10-01-preview' = {
+  name: 'my-secret-store'
+  properties: {
+    resource: 'my-secret-namespace/my-secret-store'
+    type: 'generic'
+    data: {
+      username: {
+        value: username
+      }
+      password: {
+        value: password
+      }
+    }
+  }
+}
+//SECRETSTORE
+
+//ENV
+resource env 'Applications.Core/environments@2023-10-01-preview' = {
+  name: 'my-env'
+  properties: {
+    compute: {
+      kind: 'kubernetes'
+      resourceId: 'self'
+      namespace: 'my-namespace'
+    }
+    recipeConfig: {
+      terraform: {
+        providers: {
+          postgresql: [ {
+              sslmode: 'disable'
+              port: 5432
+              secrets: {
+                username: {
+                  source: pgsSecretStore.id
+                  key: username
+                }
+                password: {
+                  source: pgsSecretStore.id
+                  key: password
+                }
+              }
+            } ]
+        }
+      }
+      env: {
+        PGHOST: 'postgres.corerp-resources-terraform-pg-app.svc.cluster.local'
+      }
+    }
+    recipes: {
+      'Applications.Core/extenders': {
+        defaultpostgres: {
+          templateKind: 'terraform'
+          // Recipe template path
+          templatePath: 'git::https://github.com/my-org/my-repo'
+        }
+      }
+    }
+  }
+}
+//ENV

docs/content/guides/recipes/terraform/howto-custom-provider/snippets/env.bicep

@@ -0,0 +1,63 @@
+//SECRETSTORE
+import radius as radius
+
+@description('username for PostgreSQL db')
+@secure()
+param username string
+
+@description('password for PostgreSQL db')
+@secure()
+param password string
+
+resource pgsSecretStore 'Applications.Core/secretStores@2023-10-01-preview' = {
+  name: 'my-secret-store'
+  properties: {
+    resource: 'my-secret-namespace/my-secret-store'
+    type: 'generic'
+    data: {
+      username: {
+        value: username
+      }
+      password: {
+        value: password
+      }
+    }
+  }
+}
+//SECRETSTORE
+
+//ENV
+resource env 'Applications.Core/environments@2023-10-01-preview' = {
+  name: 'my-env'
+  properties: {
+    compute: {
+      kind: 'kubernetes'
+      resourceId: 'self'
+      namespace: 'my-namespace'
+    }
+    recipeConfig: {
+      terraform: {
+        providers: {
+          postgresql: [ {
+              sslmode: 'disable'
+              port: 5432
+              secrets: {
+                username: {
+                  source: pgsSecretStore.id
+                  key: username
+                }
+                password: {
+                  source: pgsSecretStore.id
+                  key: password
+                }
+              }
+            } ]
+        }
+      }
+      env: {
+        PGHOST: 'postgres.corerp-resources-terraform-pg-app.svc.cluster.local'
+      }
+    }
+  }
+}
+//ENV

docs/content/guides/recipes/terraform/howto-custom-provider/snippets/postgres.tf

@@ -0,0 +1,89 @@
+terraform {
+  required_providers {
+    kubernetes = {
+      source  = "hashicorp/kubernetes"
+      version = ">= 2.0"
+    }
+    postgresql = {
+      source  = "cyrilgdn/postgresql"
+      version = "1.16.0"
+    }
+  }
+}
+
+variable "context" {
+  description = "This variable contains Radius recipe context."
+  type        = any
+}
+
+variable "password" {
+  description = "The password for the PostgreSQL database"
+  type        = string
+}
+
+resource "kubernetes_deployment" "postgres" {
+  metadata {
+    name      = "postgres"
+    namespace = var.context.runtime.kubernetes.namespace
+  }
+
+  spec {
+    selector {
+      match_labels = {
+        app = "postgres"
+      }
+    }
+
+    template {
+      metadata {
+        labels = {
+          app = "postgres"
+        }
+      }
+
+      spec {
+        container {
+          image = "postgres:latest"
+          name  = "postgres"
+
+          env {
+            name  = "POSTGRES_PASSWORD"
+            value = var.password
+          }
+
+          port {
+            container_port = 5432
+          }
+        }
+      }
+    }
+  }
+}
+
+resource "kubernetes_service" "postgres" {
+  metadata {
+    name      = "postgres"
+    namespace = var.context.runtime.kubernetes.namespace
+  }
+
+  spec {
+    selector = {
+      app = "postgres"
+    }
+
+    port {
+      port        = 5432
+      target_port = 5432
+    }
+  }
+}
+
+resource "time_sleep" "wait_20_seconds" {
+  depends_on      = [kubernetes_service.postgres]
+  create_duration = "20s"
+}
+
+resource "postgresql_database" "pg_db_test" {
+  depends_on = [time_sleep.wait_20_seconds]
+  name       = "pg_db_test"
+}