jsonconfig: Add provider configs to module calls

Add provider alias map to the JSON config module call output, allowing
consumers of this format to determine which provider configurations map
to the module-local aliases.

internal/command/jsonconfig/config.go

@@ -50,6 +50,7 @@ type moduleCall struct {
 	Module            module                 `json:"module,omitempty"`
 	VersionConstraint string                 `json:"version_constraint,omitempty"`
 	DependsOn         []string               `json:"depends_on,omitempty"`
+	Providers         map[string]string      `json:"providers,omitempty"`
 }
 
 // variables is the JSON representation of the variables provided to the current
@@ -336,6 +337,13 @@ func marshalModuleCall(c *configs.Config, mc *configs.ModuleCall, schemas *terra
 		ret.DependsOn = dependencies
 	}
 
+	if len(mc.Providers) > 0 {
+		ret.Providers = make(map[string]string, len(mc.Providers))
+		for _, ppc := range mc.Providers {
+			ret.Providers[ppc.InChild.String()] = ppc.InParent.String()
+		}
+	}
+
 	return ret
 }
 

internal/command/testdata/show-json/provider-aliasing/child/main.tf

@@ -0,0 +1,18 @@
+terraform {
+  required_providers {
+    test = {
+      source                = "hashicorp/test"
+      configuration_aliases = [test, test.second]
+    }
+  }
+}
+
+resource "test_instance" "test_primary" {
+  ami      = "primary"
+  provider = test
+}
+
+resource "test_instance" "test_secondary" {
+  ami      = "secondary"
+  provider = test.second
+}

internal/command/testdata/show-json/provider-aliasing/main.tf

@@ -0,0 +1,16 @@
+provider "test" {
+  region = "somewhere"
+}
+
+provider "test" {
+  alias  = "backup"
+  region = "elsewhere"
+}
+
+module "child" {
+  source = "./child"
+  providers = {
+    test        = test
+    test.second = test.backup
+  }
+}

internal/command/testdata/show-json/provider-aliasing/output.json

@@ -0,0 +1,150 @@
+{
+  "format_version": "1.0",
+  "planned_values": {
+    "root_module": {
+      "child_modules": [
+        {
+          "resources": [
+            {
+              "address": "module.child.test_instance.test_primary",
+              "mode": "managed",
+              "type": "test_instance",
+              "name": "test_primary",
+              "provider_name": "registry.terraform.io/hashicorp/test",
+              "schema_version": 0,
+              "values": {
+                "ami": "primary"
+              },
+              "sensitive_values": {}
+            },
+            {
+              "address": "module.child.test_instance.test_secondary",
+              "mode": "managed",
+              "type": "test_instance",
+              "name": "test_secondary",
+              "provider_name": "registry.terraform.io/hashicorp/test",
+              "schema_version": 0,
+              "values": {
+                "ami": "secondary"
+              },
+              "sensitive_values": {}
+            }
+          ],
+          "address": "module.child"
+        }
+      ]
+    }
+  },
+  "resource_changes": [
+    {
+      "address": "module.child.test_instance.test_primary",
+      "module_address": "module.child",
+      "mode": "managed",
+      "type": "test_instance",
+      "name": "test_primary",
+      "provider_name": "registry.terraform.io/hashicorp/test",
+      "change": {
+        "actions": [
+          "create"
+        ],
+        "before": null,
+        "after": {
+          "ami": "primary"
+        },
+        "after_unknown": {
+          "id": true
+        },
+        "before_sensitive": false,
+        "after_sensitive": {}
+      }
+    },
+    {
+      "address": "module.child.test_instance.test_secondary",
+      "module_address": "module.child",
+      "mode": "managed",
+      "type": "test_instance",
+      "name": "test_secondary",
+      "provider_name": "registry.terraform.io/hashicorp/test",
+      "change": {
+        "actions": [
+          "create"
+        ],
+        "before": null,
+        "after": {
+          "ami": "secondary"
+        },
+        "after_unknown": {
+          "id": true
+        },
+        "before_sensitive": false,
+        "after_sensitive": {}
+      }
+    }
+  ],
+  "configuration": {
+    "provider_config": {
+      "module.child:test": {
+        "name": "test",
+        "module_address": "module.child"
+      },
+      "test": {
+        "name": "test",
+        "expressions": {
+          "region": {
+            "constant_value": "somewhere"
+          }
+        }
+      },
+      "test.backup": {
+        "name": "test",
+        "alias": "backup",
+        "expressions": {
+          "region": {
+            "constant_value": "elsewhere"
+          }
+        }
+      }
+    },
+    "root_module": {
+      "module_calls": {
+        "child": {
+          "source": "./child",
+          "module": {
+            "resources": [
+              {
+                "address": "test_instance.test_primary",
+                "mode": "managed",
+                "type": "test_instance",
+                "name": "test_primary",
+                "provider_config_key": "child:test",
+                "expressions": {
+                  "ami": {
+                    "constant_value": "primary"
+                  }
+                },
+                "schema_version": 0
+              },
+              {
+                "address": "test_instance.test_secondary",
+                "mode": "managed",
+                "type": "test_instance",
+                "name": "test_secondary",
+                "provider_config_key": "child:test.second",
+                "expressions": {
+                  "ami": {
+                    "constant_value": "secondary"
+                  }
+                },
+                "schema_version": 0
+              }
+            ]
+          },
+          "providers": {
+            "test": "test",
+            "test.second": "test.backup"
+          }
+        }
+      }
+    }
+  }
+}

website/docs/internals/json-format.mdx

@@ -441,6 +441,14 @@ Because the configuration models are produced at a stage prior to expression eva
         // itself, using the same structure as the "root_module" object,
         // recursively describing the full module tree.
         "module": <module-configuration-representation>,
+
+        // "providers" is a map of provider aliases, as defined in the child
+        // module, to provider configurations, as defined in the root module and
+        // the "provider_configs" map above.
+        "providers": {
+          "aws": "aws",
+          "aws.secondary": "aws.foo"
+        },
       }
     }
   }