Fix how to get aws default region (#76)

internal/terraform/aws/default.go

@@ -0,0 +1,65 @@
+package aws
+
+import (
+	"os"
+
+	"github.com/carboniferio/carbonifer/internal/terraform/tfrefs"
+	"github.com/carboniferio/carbonifer/internal/utils"
+	tfjson "github.com/hashicorp/terraform-json"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/aws/aws-sdk-go/aws/ec2metadata"
+	"github.com/aws/aws-sdk-go/aws/session"
+)
+
+func GetDefaults(awsConfig *tfjson.ProviderConfig, tfPlan *tfjson.Plan, terraformRefs *tfrefs.References) {
+	log.Debugf("Reading provider config %v", awsConfig.Name)
+
+	region := getDefaultRegion(awsConfig, tfPlan)
+	if region != nil {
+		terraformRefs.ProviderConfigs["region"] = region.(string)
+	}
+}
+
+func getDefaultRegion(awsConfig *tfjson.ProviderConfig, tfPlan *tfjson.Plan) interface{} {
+	var region interface{}
+	regionExpr := awsConfig.Expressions["region"]
+	if regionExpr != nil {
+		var err error
+		region, err = utils.GetValueOfExpression(regionExpr, tfPlan)
+		if err != nil {
+			log.Fatalf("Error getting region from provider config %v", err)
+		}
+	}
+	if region == nil {
+		if os.Getenv("AWS_DEFAULT_REGION") != "" {
+			region = os.Getenv("AWS_DEFAULT_REGION")
+		}
+	}
+	if region == nil {
+		if os.Getenv("AWS_REGION") != "" {
+			region = os.Getenv("AWS_REGION")
+		}
+	}
+
+	// Check AWS Config file
+	if region == nil {
+		sess, err := session.NewSession()
+		if err != nil {
+			log.Fatalf("Error getting region from AWS config file %v", err)
+		}
+		if *sess.Config.Region != "" {
+			region = *sess.Config.Region
+		}
+	}
+
+	// Check EC2 Instance Metadata
+	if region == nil {
+		sess := session.Must(session.NewSession())
+		svc := ec2metadata.New(sess)
+		if svc.Available() {
+			region, _ = svc.Region()
+		}
+	}
+	return region
+}

internal/terraform/aws/default_test.go

@@ -0,0 +1,118 @@
+package aws
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	tfjson "github.com/hashicorp/terraform-json"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_getDefaultRegion_providerConstant(t *testing.T) {
+	awsConfigs := &tfjson.ProviderConfig{
+		Name: "aws",
+		Expressions: map[string]*tfjson.Expression{
+			"region": {
+				ExpressionData: &tfjson.ExpressionData{
+					ConstantValue: "test1",
+				},
+			},
+		},
+	}
+
+	tfPlan := &tfjson.Plan{}
+
+	region := getDefaultRegion(awsConfigs, tfPlan)
+	assert.Equal(t, "test1", region)
+
+}
+
+func Test_getDefaultRegion_providerVariable(t *testing.T) {
+	awsConfigs := &tfjson.ProviderConfig{
+		Name: "aws",
+		Expressions: map[string]*tfjson.Expression{
+			"region": {
+				ExpressionData: &tfjson.ExpressionData{
+					References: []string{"var.region"},
+				},
+			},
+		},
+	}
+
+	tfPlan := &tfjson.Plan{
+		Variables: map[string]*tfjson.PlanVariable{
+			"region": {
+				Value: "test2",
+			},
+		},
+	}
+
+	region := getDefaultRegion(awsConfigs, tfPlan)
+	assert.Equal(t, "test2", region)
+
+}
+
+func Test_getDefaultRegion_EnvVar(t *testing.T) {
+	awsConfigs := &tfjson.ProviderConfig{
+		Name:        "aws",
+		Expressions: map[string]*tfjson.Expression{},
+	}
+
+	tfPlan := &tfjson.Plan{}
+
+	t.Setenv("AWS_REGION", "test3")
+
+	region := getDefaultRegion(awsConfigs, tfPlan)
+	assert.Equal(t, "test3", region)
+
+}
+
+func Test_getDefaultRegion_EnvDefaultVar(t *testing.T) {
+	awsConfigs := &tfjson.ProviderConfig{
+		Name:        "aws",
+		Expressions: map[string]*tfjson.Expression{},
+	}
+
+	tfPlan := &tfjson.Plan{}
+
+	t.Setenv("AWS_DEFAULT_REGION", "test4")
+
+	region := getDefaultRegion(awsConfigs, tfPlan)
+	assert.Equal(t, "test4", region)
+
+}
+
+func Test_getDefaultRegion_AWSConfigFile(t *testing.T) {
+	// Create a temporary directory
+	tmpDir := t.TempDir()
+
+	// Create AWS config file
+	awsConfigFile := filepath.Join(tmpDir, "config")
+	f, err := os.Create(awsConfigFile)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+
+	_, err = io.WriteString(f, "[default]\nregion = region_from_config_file\n")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Set the AWS_SDK_LOAD_CONFIG environment variable
+	t.Setenv("AWS_SDK_LOAD_CONFIG", "1")
+	t.Setenv("AWS_CONFIG_FILE", awsConfigFile)
+
+	awsConfigs := &tfjson.ProviderConfig{
+		Name:        "aws",
+		Expressions: map[string]*tfjson.Expression{},
+	}
+
+	tfPlan := &tfjson.Plan{}
+
+	region := getDefaultRegion(awsConfigs, tfPlan)
+	assert.Equal(t, "region_from_config_file", region)
+
+}

internal/terraform/resources.go

@@ -2,7 +2,6 @@ package terraform
 
 import (
 	"encoding/json"
-	"os"
 	"strings"
 
 	"github.com/carboniferio/carbonifer/internal/resources"
@@ -66,20 +65,7 @@ func GetResources(tfPlan *tfjson.Plan) (map[string]resources.Resource, error) {
 	// Get default values
 	for provider, resConfig := range tfPlan.Config.ProviderConfigs {
 		if provider == "aws" {
-			log.Debugf("Reading provider config %v", resConfig.Name)
-			// TODO #58 Improve way we get default regions (env var, profile...)
-			var region interface{}
-			regionExpr := resConfig.Expressions["region"]
-			if regionExpr != nil {
-				region = regionExpr.ConstantValue
-			} else {
-				if os.Getenv("AWS_REGION") != "" {
-					region = os.Getenv("AWS_REGION")
-				}
-			}
-			if region != nil {
-				terraformRefs.ProviderConfigs["region"] = region.(string)
-			}
+			aws.GetDefaults(resConfig, tfPlan, &terraformRefs)
 		}
 	}
 

internal/utils/expressions.go

@@ -0,0 +1,28 @@
+package utils
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	tfjson "github.com/hashicorp/terraform-json"
+)
+
+func GetValueOfExpression(expression *tfjson.Expression, tfPlan *tfjson.Plan) (interface{}, error) {
+	if fmt.Sprintf("%T", expression.ConstantValue) != "*tfjson.unknownConstantValue" && expression.ConstantValue != nil {
+		// It's a known value, return it as is
+		return expression.ConstantValue, nil
+	}
+
+	// Constant value is not set or unknown, look up references
+	for _, reference := range expression.References {
+		ref := strings.TrimPrefix(reference, "var.")
+		if val, ok := tfPlan.Variables[ref]; ok {
+			return val.Value, nil
+		}
+	}
+
+	// No variables were found
+	return nil, errors.New("no value found for expression")
+
+}