feat: Added inputs vars deref support

terraform/constants.go

@@ -0,0 +1,5 @@
+package terraform
+
+const (
+	TF = ".tf"
+)

terraform/hcl2json.go

@@ -2,6 +2,7 @@ package terraform
 
 import (
 	"encoding/json"
+
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/hcl/v2/hclsyntax"
 )
@@ -61,7 +62,7 @@ var extractVariables = func(fileName string, fileContent string) (VariableMap, e
 		return VariableMap{}, createInvalidHCLError(diagnostics.Errs())
 	}
 
-	variables, diagnostics := extractFromFile(file)
+	variables, diagnostics := extractFromFile(fileName, file)
 	if diagnostics.HasErrors() {
 		return VariableMap{}, createInvalidHCLError(diagnostics.Errs())
 	}

terraform/hcl2json_test.go

@@ -1,10 +1,11 @@
 package terraform
 
 import (
+	"testing"
+
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/zclconf/go-cty/cty"
-	"testing"
 )
 
 func TestParseHCL2JSONSuccess(t *testing.T) {
@@ -531,48 +532,115 @@ block "label_one" {
 }
 
 func TestExtractVariablesSuccess(t *testing.T) {
+	type TestInput struct {
+		fileName    string
+		fileContent string
+	}
+
 	type test struct {
 		name     string
-		input    string
+		input    TestInput
 		expected VariableMap
 	}
 	tests := []test{
 		{
 			name: "Simple variable block with no default",
-			input: `
-variable "test" {
-	type = "string"
-}`,
+			input: TestInput{
+				fileName: "test.tf",
+				fileContent: `
+				variable "test" {
+					type = "string"
+				}`,
+			},
+			expected: VariableMap{
+				"var": cty.ObjectVal(VariableMap{}),
+				"local": cty.ObjectVal(VariableMap{
+					"dummy": cty.StringVal("dummy"),
+				}),
+			},
+		},
+		{
+			name: "Simple variable block with default",
+			input: TestInput{
+				fileName: "test.tf",
+				fileContent: `
+				variable "test" {
+					type = "string"
+					default = "test"
+				}`,
+			},
 			expected: VariableMap{
 				"var": cty.ObjectVal(VariableMap{
-					"dummy": cty.StringVal("dummy_value"),
+					"test": cty.StringVal("test"),
 				}),
 				"local": cty.ObjectVal(VariableMap{
-					"dummy": cty.StringVal("dummy_local"),
+					"dummy": cty.StringVal("dummy"),
 				}),
 			},
 		},
 		{
-			name: "Simple variable block with default",
-			input: `
-variable "test" {
-	type = "string"
-	default = "test"
-}`,
+			name: "Variable with null value",
+			input: TestInput{
+				fileName: "test.tf",
+				fileContent: `
+				variable "test" {
+					type = "string"
+					default = null
+				}`,
+			},
+			expected: VariableMap{
+				"var": cty.ObjectVal(VariableMap{}),
+				"local": cty.ObjectVal(VariableMap{
+					"dummy": cty.StringVal("dummy"),
+				}),
+			},
+		},
+		{
+			name: "Two variable one with null value and the other with valid value",
+			input: TestInput{
+				fileName: "test.tf",
+				fileContent: `
+				variable "nullTest" {
+					type = "string"
+					default = null
+				}
+				
+				variable "test" {
+					type = "string"
+					default = "test"
+				}`,
+			},
 			expected: VariableMap{
 				"var": cty.ObjectVal(VariableMap{
-					"dummy": cty.StringVal("dummy_value"),
+					"test": cty.StringVal("test"),
 				}),
 				"local": cty.ObjectVal(VariableMap{
-					"dummy": cty.StringVal("dummy_local"),
+					"dummy": cty.StringVal("dummy"),
+				}),
+			},
+		},
+		{
+			name: "Non-variable block",
+			input: TestInput{
+				fileName: "test.tf",
+				fileContent: `
+				provider "google" {
+					project = "acme-app"
+					default  = "us-central1"
+				}`,
+			},
+			expected: VariableMap{
+				"var": cty.ObjectVal(VariableMap{}),
+				"local": cty.ObjectVal(VariableMap{
+					"dummy": cty.StringVal("dummy"),
 				}),
 			},
 		},
 	}
 
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			actual, err := extractVariables("test", tc.input)
+			actual, err := extractVariables(tc.input.fileName, tc.input.fileContent)
 			require.Nil(t, err)
 			assert.Equal(t, tc.expected, actual)
 		})
@@ -585,16 +653,27 @@ resource "aws_security_group" "allow_ssh" {
 	name        = "allow_ssh"
 	description = "Allow SSH inbound from anywhere"
 	cidr_blocks = var.dummy
+}
+
+variable "dummy" {
+	type = "string"
+	default = "dummy"
 }`
 	jsonOutput := `{
 	"resource": {
 		"aws_security_group": {
 			"allow_ssh": {
-				"cidr_blocks": "dummy_value",
+				"cidr_blocks": "dummy",
 				"description": "Allow SSH inbound from anywhere",
 				"name": "allow_ssh"
 			}
 		}
+	},
+	"variable": {
+		"dummy": {
+			"default": "dummy",
+			"type": "string"
+		}
 	}
 }`
 	type test struct {

terraform/schemas.go

@@ -0,0 +1,16 @@
+package terraform
+
+import "github.com/hashicorp/hcl/v2"
+
+//Taken from https://github.com/hashicorp/terraform/blob/f266d1ee82d1fa4d882c146cc131fec4bef753cf/internal/configs/parser_config.go#L214
+// tfFileSchema is the schema for the top-level of a config file. We use
+// the low-level HCL API for this level so we can easily deal with each
+// block type separately with its own decoding logic.
+var tfFileVariableSchema = &hcl.BodySchema{
+	Blocks: []hcl.BlockHeaderSchema{
+		{
+			Type:       "variable",
+			LabelNames: []string{"name"},
+		},
+	},
+}

terraform/variables.go

@@ -5,21 +5,51 @@ import (
 	"github.com/zclconf/go-cty/cty"
 )
 
-func extractFromFile(file *hcl.File) (VariableMap, hcl.Diagnostics) {
-	// TODO: remove temporary dummy variables
-	// implement "var" when we do input variables and default values
+type VariableMap map[string]cty.Value
+
+func extractFromFile(filename string, file *hcl.File) (VariableMap, hcl.Diagnostics) {
+	// TODO: remove temporary dummy locals
 	// implement "local" when we do local values
+
+	varMap, hclDiags := extractFromTfFile(filename, file)
+	if hclDiags.HasErrors() {
+		return VariableMap{}, hclDiags
+	}
+
 	return VariableMap{
-		"var": cty.ObjectVal(VariableMap{
-			"dummy": cty.StringVal("dummy_value"),
-		}),
+		"var": cty.ObjectVal(varMap),
 		"local": cty.ObjectVal(VariableMap{
-			"dummy": cty.StringVal("dummy_local"),
+			"dummy": cty.StringVal("dummy"),
 		}),
-	}, nil
+	}, hclDiags
 }
 
-type VariableMap map[string]cty.Value
+func extractFromTfFile(filename string, file *hcl.File) (VariableMap, hcl.Diagnostics) {
+	varMap := VariableMap{}
+	bodyContent, _, hclDiags := file.Body.PartialContent(tfFileVariableSchema)
+
+	if hclDiags.HasErrors() {
+		return VariableMap{}, hclDiags
+	}
+
+	for _, block := range bodyContent.Blocks {
+		name := block.Labels[0]
+
+		attrs, _ := block.Body.JustAttributes()
+
+		defaultValue := attrs["default"]
+		if defaultValue != nil {
+			value, diags := defaultValue.Expr.Value(&hcl.EvalContext{Functions: terraformFunctions})
+			if diags.HasErrors() || value.IsNull() {
+				continue
+			}
+
+			varMap[name] = value
+		}
+	}
+
+	return varMap, hclDiags
+}
 
 func mergeVariables(variableMaps []VariableMap) VariableMap {
 	combinedVariableMaps := make(VariableMap)