cli: Fix for provider requirements in JSON plan

The JSON plan output format includes a serialized, simplified version of
the configuration. One component of this config is a map of provider
configurations, which includes version constraints.

Until now, only version constraints specified in the provider config
blocks were exposed in the JSON plan output. This is a deprecated method
of specifying provider versions, and the recommended use of a
required_providers block resulted in the version constraints being
omitted.

This commit fixes this with two changes:

- When processing the provider configurations from a module, output the
  fully-merged version constraints for the entire module, instead of any
  constraints set in the provider configuration block itself;
- After all provider configurations are processed, iterate over the
  required_providers entries to ensure that any configuration-less
  providers are output to the JSON plan too.

No changes are necessary to the structure of the JSON plan output, so
this is effectively a semantic level bug fix.

command/jsonconfig/config.go

@@ -11,6 +11,7 @@ import (
 	"github.com/hashicorp/terraform/addrs"
 	"github.com/hashicorp/terraform/configs"
 	"github.com/hashicorp/terraform/configs/configschema"
+	"github.com/hashicorp/terraform/internal/getproviders"
 	"github.com/hashicorp/terraform/terraform"
 )
 
@@ -139,19 +140,61 @@ func marshalProviderConfigs(
 		return
 	}
 
+	// We want to determine only the provider requirements from this module,
+	// ignoring any descendants.  Disregard any diagnostics when determining
+	// requirements because we want this marshalling to succeed even if there
+	// are invalid constraints.
+	reqs, _ := c.ProviderRequirementsShallow()
+
+	// Add an entry for each provider configuration block in the module.
 	for k, pc := range c.Module.ProviderConfigs {
 		providerFqn := c.ProviderForConfigAddr(addrs.LocalProviderConfig{LocalName: pc.Name})
 		schema := schemas.ProviderConfig(providerFqn)
-		p := providerConfig{
-			Name:              pc.Name,
-			Alias:             pc.Alias,
-			ModuleAddress:     c.Path.String(),
-			Expressions:       marshalExpressions(pc.Config, schema),
-			VersionConstraint: pc.Version.Required.String(),
-		}
-		absPC := opaqueProviderKey(k, c.Path.String())
 
-		m[absPC] = p
+		p := providerConfig{
+			Name:          pc.Name,
+			Alias:         pc.Alias,
+			ModuleAddress: c.Path.String(),
+			Expressions:   marshalExpressions(pc.Config, schema),
+		}
+
+		// Store the fully resolved provider version constraint, rather than
+		// using the version argument in the configuration block. This is both
+		// future proof (for when we finish the deprecation of the provider config
+		// version argument) and more accurate (as it reflects the full set of
+		// constraints, in case there are multiple).
+		if vc, ok := reqs[providerFqn]; ok {
+			p.VersionConstraint = getproviders.VersionConstraintsString(vc)
+		}
+
+		key := opaqueProviderKey(k, c.Path.String())
+
+		m[key] = p
+	}
+
+	// Ensure that any required providers with no associated configuration
+	// block are included in the set.
+	for k, pr := range c.Module.ProviderRequirements.RequiredProviders {
+		// If there exists a value for this provider, we have nothing to add
+		// to it, so skip.
+		key := opaqueProviderKey(k, c.Path.String())
+		if _, exists := m[key]; exists {
+			continue
+		}
+
+		// Given no provider configuration block exists, the only fields we can
+		// fill here are the local name, module address, and version
+		// constraints.
+		p := providerConfig{
+			Name:          pr.Name,
+			ModuleAddress: c.Path.String(),
+		}
+
+		if vc, ok := reqs[pr.Type]; ok {
+			p.VersionConstraint = getproviders.VersionConstraintsString(vc)
+		}
+
+		m[key] = p
 	}
 
 	// Must also visit our child modules, recursively.

command/testdata/show-json/provider-version-no-config/main.tf

@@ -0,0 +1,21 @@
+terraform {
+  required_providers {
+    test = {
+      source = "hashicorp/test"
+      version = ">= 1.2.3"
+    }
+  }
+}
+
+variable "test_var" {
+  default = "bar"
+}
+
+resource "test_instance" "test" {
+  ami   = var.test_var
+  count = 3
+}
+
+output "test" {
+  value = var.test_var
+}

command/testdata/show-json/provider-version-no-config/output.json

@@ -0,0 +1,184 @@
+{
+    "format_version": "0.1",
+    "variables": {
+        "test_var": {
+            "value": "bar"
+        }
+    },
+    "planned_values": {
+        "outputs": {
+            "test": {
+                "sensitive": false,
+                "value": "bar"
+            }
+        },
+        "root_module": {
+            "resources": [
+                {
+                    "address": "test_instance.test[0]",
+                    "index": 0,
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_name": "registry.terraform.io/hashicorp/test",
+                    "schema_version": 0,
+                    "values": {
+                        "ami": "bar"
+                    }
+                },
+                {
+                    "address": "test_instance.test[1]",
+                    "index": 1,
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_name": "registry.terraform.io/hashicorp/test",
+                    "schema_version": 0,
+                    "values": {
+                        "ami": "bar"
+                    }
+                },
+                {
+                    "address": "test_instance.test[2]",
+                    "index": 2,
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_name": "registry.terraform.io/hashicorp/test",
+                    "schema_version": 0,
+                    "values": {
+                        "ami": "bar"
+                    }
+                }
+            ]
+        }
+    },
+    "prior_state": {
+        "format_version": "0.1",
+        "values": {
+            "outputs": {
+                "test": {
+                    "sensitive": false,
+                    "value": "bar"
+                }
+            },
+            "root_module": {}
+        }
+    },
+    "resource_changes": [
+        {
+            "address": "test_instance.test[0]",
+            "index": 0,
+            "mode": "managed",
+            "type": "test_instance",
+            "provider_name": "registry.terraform.io/hashicorp/test",
+            "name": "test",
+            "change": {
+                "actions": [
+                    "create"
+                ],
+                "before": null,
+                "after_unknown": {
+                    "id": true
+                },
+                "after": {
+                    "ami": "bar"
+                }
+            }
+        },
+        {
+            "address": "test_instance.test[1]",
+            "index": 1,
+            "mode": "managed",
+            "type": "test_instance",
+            "provider_name": "registry.terraform.io/hashicorp/test",
+            "name": "test",
+            "change": {
+                "actions": [
+                    "create"
+                ],
+                "before": null,
+                "after_unknown": {
+                    "id": true
+                },
+                "after": {
+                    "ami": "bar"
+                }
+            }
+        },
+        {
+            "address": "test_instance.test[2]",
+            "index": 2,
+            "mode": "managed",
+            "type": "test_instance",
+            "provider_name": "registry.terraform.io/hashicorp/test",
+            "name": "test",
+            "change": {
+                "actions": [
+                    "create"
+                ],
+                "before": null,
+                "after_unknown": {
+                    "id": true
+                },
+                "after": {
+                    "ami": "bar"
+                }
+            }
+        }
+    ],
+    "output_changes": {
+        "test": {
+            "actions": [
+                "create"
+            ],
+            "before": null,
+            "after": "bar",
+            "after_unknown": false
+        }
+    },
+    "configuration": {
+        "provider_config": {
+            "test": {
+                "name": "test",
+                "version_constraint": ">= 1.2.3"
+            }
+        },
+        "root_module": {
+            "outputs": {
+                "test": {
+                    "expression": {
+                        "references": [
+                            "var.test_var"
+                        ]
+                    }
+                }
+            },
+            "resources": [
+                {
+                    "address": "test_instance.test",
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_config_key": "test",
+                    "schema_version": 0,
+                    "expressions": {
+                        "ami": {
+                            "references": [
+                                "var.test_var"
+                            ]
+                        }
+                    },
+                    "count_expression": {
+                        "constant_value": 3
+                    }
+                }
+            ],
+            "variables": {
+                "test_var": {
+                    "default": "bar"
+                }
+            }
+        }
+    }
+}

command/testdata/show-json/provider-version/main.tf

@@ -0,0 +1,26 @@
+terraform {
+  required_providers {
+    test = {
+      source = "hashicorp/test"
+      version = ">= 1.2.3"
+    }
+  }
+}
+
+provider "test" {
+  region = "somewhere"
+  version = "1.2.3"
+}
+
+variable "test_var" {
+  default = "bar"
+}
+
+resource "test_instance" "test" {
+  ami   = var.test_var
+  count = 3
+}
+
+output "test" {
+  value = var.test_var
+}

command/testdata/show-json/provider-version/output.json

@@ -0,0 +1,189 @@
+{
+    "format_version": "0.1",
+    "variables": {
+        "test_var": {
+            "value": "bar"
+        }
+    },
+    "planned_values": {
+        "outputs": {
+            "test": {
+                "sensitive": false,
+                "value": "bar"
+            }
+        },
+        "root_module": {
+            "resources": [
+                {
+                    "address": "test_instance.test[0]",
+                    "index": 0,
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_name": "registry.terraform.io/hashicorp/test",
+                    "schema_version": 0,
+                    "values": {
+                        "ami": "bar"
+                    }
+                },
+                {
+                    "address": "test_instance.test[1]",
+                    "index": 1,
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_name": "registry.terraform.io/hashicorp/test",
+                    "schema_version": 0,
+                    "values": {
+                        "ami": "bar"
+                    }
+                },
+                {
+                    "address": "test_instance.test[2]",
+                    "index": 2,
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_name": "registry.terraform.io/hashicorp/test",
+                    "schema_version": 0,
+                    "values": {
+                        "ami": "bar"
+                    }
+                }
+            ]
+        }
+    },
+    "prior_state": {
+        "format_version": "0.1",
+        "values": {
+            "outputs": {
+                "test": {
+                    "sensitive": false,
+                    "value": "bar"
+                }
+            },
+            "root_module": {}
+        }
+    },
+    "resource_changes": [
+        {
+            "address": "test_instance.test[0]",
+            "index": 0,
+            "mode": "managed",
+            "type": "test_instance",
+            "provider_name": "registry.terraform.io/hashicorp/test",
+            "name": "test",
+            "change": {
+                "actions": [
+                    "create"
+                ],
+                "before": null,
+                "after_unknown": {
+                    "id": true
+                },
+                "after": {
+                    "ami": "bar"
+                }
+            }
+        },
+        {
+            "address": "test_instance.test[1]",
+            "index": 1,
+            "mode": "managed",
+            "type": "test_instance",
+            "provider_name": "registry.terraform.io/hashicorp/test",
+            "name": "test",
+            "change": {
+                "actions": [
+                    "create"
+                ],
+                "before": null,
+                "after_unknown": {
+                    "id": true
+                },
+                "after": {
+                    "ami": "bar"
+                }
+            }
+        },
+        {
+            "address": "test_instance.test[2]",
+            "index": 2,
+            "mode": "managed",
+            "type": "test_instance",
+            "provider_name": "registry.terraform.io/hashicorp/test",
+            "name": "test",
+            "change": {
+                "actions": [
+                    "create"
+                ],
+                "before": null,
+                "after_unknown": {
+                    "id": true
+                },
+                "after": {
+                    "ami": "bar"
+                }
+            }
+        }
+    ],
+    "output_changes": {
+        "test": {
+            "actions": [
+                "create"
+            ],
+            "before": null,
+            "after": "bar",
+            "after_unknown": false
+        }
+    },
+    "configuration": {
+        "provider_config": {
+            "test": {
+                "name": "test",
+                "expressions": {
+                    "region": {
+                        "constant_value": "somewhere"
+                    }
+                },
+                "version_constraint": ">= 1.2.3, 1.2.3"
+            }
+        },
+        "root_module": {
+            "outputs": {
+                "test": {
+                    "expression": {
+                        "references": [
+                            "var.test_var"
+                        ]
+                    }
+                }
+            },
+            "resources": [
+                {
+                    "address": "test_instance.test",
+                    "mode": "managed",
+                    "type": "test_instance",
+                    "name": "test",
+                    "provider_config_key": "test",
+                    "schema_version": 0,
+                    "expressions": {
+                        "ami": {
+                            "references": [
+                                "var.test_var"
+                            ]
+                        }
+                    },
+                    "count_expression": {
+                        "constant_value": 3
+                    }
+                }
+            ],
+            "variables": {
+                "test_var": {
+                    "default": "bar"
+                }
+            }
+        }
+    }
+}

configs/config.go

@@ -190,6 +190,18 @@ func (c *Config) ProviderRequirements() (getproviders.Requirements, hcl.Diagnost
 	return reqs, diags
 }
 
+// ProviderRequirementsShallow searches only the direct receiver for explicit
+// and implicit dependencies on providers. Descendant modules are ignored.
+//
+// If the returned diagnostics includes errors then the resulting Requirements
+// may be incomplete.
+func (c *Config) ProviderRequirementsShallow() (getproviders.Requirements, hcl.Diagnostics) {
+	reqs := make(getproviders.Requirements)
+	diags := c.addProviderRequirements(reqs, false)
+
+	return reqs, diags
+}
+
 // ProviderRequirementsByModule searches the full tree of modules under the
 // receiver for both explicit and implicit dependencies on providers,
 // constructing a tree where the requirements are broken out by module.

configs/config_test.go

@@ -157,6 +157,42 @@ func TestConfigProviderRequirements(t *testing.T) {
 	}
 }
 
+func TestConfigProviderRequirementsShallow(t *testing.T) {
+	cfg, diags := testNestedModuleConfigFromDir(t, "testdata/provider-reqs")
+	// TODO: Version Constraint Deprecation.
+	// Once we've removed the version argument from provider configuration
+	// blocks, this can go back to expected 0 diagnostics.
+	// assertNoDiagnostics(t, diags)
+	assertDiagnosticCount(t, diags, 1)
+	assertDiagnosticSummary(t, diags, "Version constraints inside provider configuration blocks are deprecated")
+
+	tlsProvider := addrs.NewProvider(
+		addrs.DefaultRegistryHost,
+		"hashicorp", "tls",
+	)
+	nullProvider := addrs.NewDefaultProvider("null")
+	randomProvider := addrs.NewDefaultProvider("random")
+	impliedProvider := addrs.NewDefaultProvider("implied")
+	terraformProvider := addrs.NewBuiltInProvider("terraform")
+	configuredProvider := addrs.NewDefaultProvider("configured")
+
+	got, diags := cfg.ProviderRequirementsShallow()
+	assertNoDiagnostics(t, diags)
+	want := getproviders.Requirements{
+		// the nullProvider constraint is only from the root module
+		nullProvider:       getproviders.MustParseVersionConstraints("~> 2.0.0"),
+		randomProvider:     getproviders.MustParseVersionConstraints("~> 1.2.0"),
+		tlsProvider:        getproviders.MustParseVersionConstraints("~> 3.0"),
+		configuredProvider: getproviders.MustParseVersionConstraints("~> 1.4"),
+		impliedProvider:    nil,
+		terraformProvider:  nil,
+	}
+
+	if diff := cmp.Diff(want, got); diff != "" {
+		t.Errorf("wrong result\n%s", diff)
+	}
+}
+
 func TestConfigProviderRequirementsByModule(t *testing.T) {
 	cfg, diags := testNestedModuleConfigFromDir(t, "testdata/provider-reqs")
 	// TODO: Version Constraint Deprecation.