Adds support for Terragrunt JSON configuration files

README.md

@@ -20,9 +20,9 @@ for a quick introduction to Terragrunt.
    downloading the binary for your OS, renaming it to `terragrunt`, and adding it to your PATH.
      * See the [Install Terragrunt](#install-terragrunt) docs for other installation options.
 
-1. Go into a folder with your Terraform configurations (`.tf` files) and create a `terragrunt.hcl` file that contains
-   the configuration for Terragrunt (Terragrunt configuration uses the exact language, HCL, as Terraform). Here's an
-   example of using Terragrunt to keep your Terraform backend configuration DRY (check out the [Use cases](#use-cases)
+1. Go into a folder with your Terraform configurations (`.tf` files) and create a `terragrunt.hcl` or `terragrunt.hcl.json` file that contains 
+   the configuration for Terragrunt (Terragrunt configuration uses the exact language, HCL, as Terraform. [JSON configuration syntax](https://www.terraform.io/docs/configuration/syntax-json.html) is also supported.). Here's an 
+   example of using Terragrunt to keep your Terraform backend configuration DRY (check out the [Use cases](#use-cases) 
    section for other types of configuration Terragrunt supports):
 
     ```hcl
@@ -35,6 +35,22 @@ for a quick introduction to Terragrunt.
         region         = "us-east-1"
         encrypt        = true
         dynamodb_table = "my-lock-table"
+      }   
+    }
+    ```
+
+    ```json
+    # terragrunt.hcl.json example
+    {
+      "remote_state":{
+        "backend": "s3",
+        "config":{
+          "bucket"         : "my-terraform-state",
+          "key"            : "${path_relative_to_include()}/terraform.tfstate",
+          "region"         : "us-east-1",
+          "encrypt"        : true,
+          "dynamodb_table" : "my-lock-table"
+        }
       }
     }
     ```

cli/args.go

@@ -63,7 +63,7 @@ func parseTerragruntOptionsFromArgs(args []string, writer, errWriter io.Writer)
 		return nil, err
 	}
 	if terragruntConfigPath == "" {
-		terragruntConfigPath = config.DefaultConfigPath(workingDir)
+		terragruntConfigPath = config.GetDefaultConfigPath(workingDir)
 	}
 
 	terraformPath, err := parseStringArg(args, OPT_TERRAGRUNT_TFPATH, os.Getenv("TERRAGRUNT_TFPATH"))

config/config.go

@@ -19,6 +19,7 @@ import (
 )
 
 const DefaultTerragruntConfigPath = "terragrunt.hcl"
+const DefaultTerragruntJsonConfigPath = "terragrunt.hcl.json"
 
 // TerragruntConfig represents a parsed and expanded configuration
 type TerragruntConfig struct {
@@ -186,11 +187,25 @@ func (conf *TerraformExtraArguments) String() string {
 		conf.EnvVars)
 }
 
-// Return the default path to use for the Terragrunt configuration file in the given directory
+// Return the default hcl path to use for the Terragrunt configuration file in the given directory
 func DefaultConfigPath(workingDir string) string {
 	return util.JoinPath(workingDir, DefaultTerragruntConfigPath)
 }
 
+// Return the default path to use for the Terragrunt Json configuration file in the given directory
+func DefaultJsonConfigPath(workingDir string) string {
+	return util.JoinPath(workingDir, DefaultTerragruntJsonConfigPath)
+}
+
+// Return the default path to use for the Terragrunt configuration that exists within the path giving preference to `terragrunt.hcl`
+func GetDefaultConfigPath(workingDir string) string {
+	if util.FileNotExists(DefaultConfigPath(workingDir)) && util.FileExists(DefaultJsonConfigPath(workingDir)) {
+		return DefaultJsonConfigPath(workingDir)
+	}
+
+	return DefaultConfigPath(workingDir)
+}
+
 // Returns a list of all Terragrunt config files in the given path or any subfolder of the path. A file is a Terragrunt
 // config file if it has a name as returned by the DefaultConfigPath method
 func FindConfigFilesInPath(rootPath string, terragruntOptions *options.TerragruntOptions) ([]string, error) {
@@ -207,7 +222,7 @@ func FindConfigFilesInPath(rootPath string, terragruntOptions *options.Terragrun
 		}
 
 		if isTerragruntModule {
-			configFiles = append(configFiles, DefaultConfigPath(path))
+			configFiles = append(configFiles, GetDefaultConfigPath(path))
 		}
 
 		return nil
@@ -217,7 +232,7 @@ func FindConfigFilesInPath(rootPath string, terragruntOptions *options.Terragrun
 }
 
 // Returns true if the given path with the given FileInfo contains a Terragrunt module and false otherwise. A path
-// contains a Terragrunt module if it contains a Terragrunt configuration file (terragrunt.hcl) and is not a cache
+// contains a Terragrunt module if it contains a Terragrunt configuration file (terragrunt.hcl, terragrunt.hcl.json) and is not a cache
 // or download dir.
 func containsTerragruntModule(path string, info os.FileInfo, terragruntOptions *options.TerragruntOptions) (bool, error) {
 	if !info.IsDir() {
@@ -244,7 +259,7 @@ func containsTerragruntModule(path string, info os.FileInfo, terragruntOptions *
 		return false, err
 	}
 
-	return util.FileExists(DefaultConfigPath(path)), nil
+	return util.FileExists(GetDefaultConfigPath(path)), nil
 }
 
 // Read the Terragrunt config file from its default location
@@ -417,6 +432,15 @@ func parseHcl(parser *hclparse.Parser, hcl string, filename string) (file *hcl.F
 		}
 	}()
 
+	if filepath.Ext(filename) == ".json" {
+		file, parseDiagnostics := parser.ParseJSON([]byte(hcl), filename)
+		if parseDiagnostics != nil && parseDiagnostics.HasErrors() {
+			return nil, parseDiagnostics
+		}
+
+		return file, nil
+	}
+
 	file, parseDiagnostics := parser.ParseHCL([]byte(hcl), filename)
 	if parseDiagnostics != nil && parseDiagnostics.HasErrors() {
 		return nil, parseDiagnostics

config/config_helpers.go

@@ -255,7 +255,7 @@ func findInParentFolders(params []string, include *IncludeConfig, terragruntOpti
 			return "", errors.WithStackTrace(ParentFileNotFound{Path: terragruntOptions.TerragruntConfigPath, File: fileToFindStr, Cause: "Traversed all the way to the root"})
 		}
 
-		fileToFind := DefaultConfigPath(currentDir)
+		fileToFind := GetDefaultConfigPath(currentDir)
 		if fileToFindParam != "" {
 			fileToFind = util.JoinPath(currentDir, fileToFindParam)
 		}