Allows setting terraform_binary in terragrunt.hcl

Related to gruntwork-io#743
springload · Aug 7, 2019 · ccc111f · ccc111f
1 parent b398b48
commit ccc111f
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Showing 6 changed files with 78 additions and 39 deletions.
diff --git a/README.md b/README.md
@@ -2152,6 +2152,12 @@ If you run `terragrunt hclfmt` at the `root`, this will update:
 Additionally, there's a flag `--terragrunt-check`. It allows to validating if files are properly formatted. It does not
 rewrite files and in case of invalid format, it will return an error with exit status 0.
 
+#### terraform_binary
+
+The terragrunt `terraform_binary` string option can be used to override the default terraform binary path (which is `terraform`).
+
+The precedence is as follows: `--terragrunt-tfpath` command line option -> `TERRAGRUNT_TFPATH` env variable -> `terragrunt.hcl` in the module directory -> included `terragrunt.hcl`
+
 ### Clearing the Terragrunt cache
 
 Terragrunt creates a `.terragrunt-cache` folder in the current working directory as its scratch directory. It downloads

diff --git a/_docs/migration_guides/upgrading_to_terragrunt_0.19.x.md b/_docs/migration_guides/upgrading_to_terragrunt_0.19.x.md
@@ -27,6 +27,7 @@ to Terragrunt 0.19.x and newer:
 1. [Use first-class expressions](#use-first-class-expressions)
 1. [Check attributes vs blocks usage](#check-attributes-vs-blocks-usage)
 1. [Rename a few built-in functions ](#rename-a-few-built-in-functions)
+1. [Use terraform \<0.12](#use-older-terraform)
 
 Check out [this PR in the terragrunt-infrastructure-live-example 
 repo](https://github.com/gruntwork-io/terragrunt-infrastructure-live-example/pull/17) for an example of what the code 
@@ -272,3 +273,15 @@ Two built-in functions were renamed:
 1. `get_parent_tfvars_dir()` is now called `get_parent_terragrunt_dir()`.   
 
 Make sure to make the corresponding updates in your `terragrunt.hcl` file!
+
+### Use older Terraform
+
+Although it is not officiall supported and not tested, it is still possible to use terraform<0.12 with terragrunt >=0.19.
+
+Just install a different version of terraform into a directory of your choice outside of `PATH` and specify path to the binary in `terragrunt.hcl` as `terraform_binary`:
+
+```hcl
+
+terraform_binary = "~/bin/terraform-v11/terraform"
+
+```
diff --git a/cli/args.go b/cli/args.go
@@ -71,7 +71,7 @@ func parseTerragruntOptionsFromArgs(args []string, writer, errWriter io.Writer)
 		return nil, err
 	}
 	if terraformPath == "" {
-		terraformPath = "terraform"
+		terraformPath = options.TERRAFORM_DEFAULT_PATH
 	}
 
 	terraformSource, err := parseStringArg(args, OPT_TERRAGRUNT_SOURCE, os.Getenv("TERRAGRUNT_SOURCE"))

diff --git a/cli/cli_app.go b/cli/cli_app.go
@@ -150,7 +150,7 @@ AUTHOR(S):
 var MODULE_REGEX = regexp.MustCompile(`module[[:blank:]]+".+"`)
 
 // This uses the constraint syntax from https://github.com/hashicorp/go-version
-// This version of Terragrunt only works with Terraform 0.12.0 and above
+// This version of Terragrunt was tested to work with Terraform 0.12.0 and above only
 const DEFAULT_TERRAFORM_VERSION_CONSTRAINT = ">= v0.12.0"
 
 const TERRAFORM_EXTENSION_GLOB = "*.tf"
@@ -241,10 +241,17 @@ func runTerragrunt(terragruntOptions *options.TerragruntOptions) error {
 	}
 
 	terragruntConfig, err := config.ReadTerragruntConfig(terragruntOptions)
+
 	if err != nil {
 		return err
 	}
 
+	if terragruntOptions.TerraformPath == options.TERRAFORM_DEFAULT_PATH { // not changed from default
+		if terragruntConfig.TerraformBinary != "" {
+			terragruntOptions.TerraformPath = terragruntConfig.TerraformBinary
+		}
+	}
+
 	if terragruntConfig.Skip {
 		terragruntOptions.Logger.Printf("Skipping terragrunt module %s due to skip = true.",
 			terragruntOptions.TerragruntConfigPath)

diff --git a/config/config.go b/config/config.go
@@ -22,14 +22,15 @@ const DefaultTerragruntConfigPath = "terragrunt.hcl"
 
 // TerragruntConfig represents a parsed and expanded configuration
 type TerragruntConfig struct {
-	Terraform      *TerraformConfig
-	RemoteState    *remote.RemoteState
-	Dependencies   *ModuleDependencies
-	PreventDestroy bool
-	Skip           bool
-	IamRole        string
-	Inputs         map[string]interface{}
-	Locals         map[string]interface{}
+	Terraform       *TerraformConfig
+	TerraformBinary string
+	RemoteState     *remote.RemoteState
+	Dependencies    *ModuleDependencies
+	PreventDestroy  bool
+	Skip            bool
+	IamRole         string
+	Inputs          map[string]interface{}
+	Locals          map[string]interface{}
 }
 
 func (conf *TerragruntConfig) String() string {
@@ -39,14 +40,15 @@ func (conf *TerragruntConfig) String() string {
 // terragruntConfigFile represents the configuration supported in a Terragrunt configuration file (i.e.
 // terragrunt.hcl)
 type terragruntConfigFile struct {
-	Terraform      *TerraformConfig       `hcl:"terraform,block"`
-	Inputs         *cty.Value             `hcl:"inputs,attr"`
-	Include        *IncludeConfig         `hcl:"include,block"`
-	RemoteState    *remoteStateConfigFile `hcl:"remote_state,block"`
-	Dependencies   *ModuleDependencies    `hcl:"dependencies,block"`
-	PreventDestroy *bool                  `hcl:"prevent_destroy,attr"`
-	Skip           *bool                  `hcl:"skip,attr"`
-	IamRole        *string                `hcl:"iam_role,attr"`
+	Terraform       *TerraformConfig       `hcl:"terraform,block"`
+	TerraformBinary *string                `hcl:"terraform_binary,attr"`
+	Inputs          *cty.Value             `hcl:"inputs,attr"`
+	Include         *IncludeConfig         `hcl:"include,block"`
+	RemoteState     *remoteStateConfigFile `hcl:"remote_state,block"`
+	Dependencies    *ModuleDependencies    `hcl:"dependencies,block"`
+	PreventDestroy  *bool                  `hcl:"prevent_destroy,attr"`
+	Skip            *bool                  `hcl:"skip,attr"`
+	IamRole         *string                `hcl:"iam_role,attr"`
 
 	// This struct is used for validating and parsing the entire terragrunt config. Since locals are evaluated in a
 	// completely separate cycle, it should not be evaluated here. Otherwise, we can't support self referencing other
@@ -433,6 +435,10 @@ func mergeConfigWithIncludedConfig(config *TerragruntConfig, includedConfig *Ter
 		includedConfig.IamRole = config.IamRole
 	}
 
+	if config.TerraformBinary != "" {
+		includedConfig.TerraformBinary = config.TerraformBinary
+	}
+
 	if config.Inputs != nil {
 		includedConfig.Inputs = mergeInputs(config.Inputs, includedConfig.Inputs)
 	}
@@ -586,6 +592,10 @@ func convertToTerragruntConfig(terragruntConfigFromFile *terragruntConfigFile, c
 	terragruntConfig.Terraform = terragruntConfigFromFile.Terraform
 	terragruntConfig.Dependencies = terragruntConfigFromFile.Dependencies
 
+	if terragruntConfigFromFile.TerraformBinary != nil {
+		terragruntConfig.TerraformBinary = *terragruntConfigFromFile.TerraformBinary
+	}
+
 	if terragruntConfigFromFile.PreventDestroy != nil {
 		terragruntConfig.PreventDestroy = *terragruntConfigFromFile.PreventDestroy
 	}

diff --git a/options/options.go b/options/options.go
@@ -21,6 +21,9 @@ var TERRAFORM_COMMANDS_WITH_SUBCOMMAND = []string{
 
 const DEFAULT_MAX_FOLDERS_TO_CHECK = 100
 
+// TERRAFORM_DEFAULT_PATH just takes terraform from the path
+const TERRAFORM_DEFAULT_PATH = "terraform"
+
 const TerragruntCacheDir = ".terragrunt-cache"
 
 // TerragruntOptions represents options that configure the behavior of the Terragrunt program
@@ -124,7 +127,7 @@ func NewTerragruntOptions(terragruntConfigPath string) (*TerragruntOptions, erro
 
 	return &TerragruntOptions{
 		TerragruntConfigPath:       terragruntConfigPath,
-		TerraformPath:              "terraform",
+		TerraformPath:              TERRAFORM_DEFAULT_PATH,
 		TerraformCommand:           "",
 		AutoInit:                   true,
 		NonInteractive:             false,
@@ -137,16 +140,16 @@ func NewTerragruntOptions(terragruntConfigPath string) (*TerragruntOptions, erro
 		DownloadDir:                downloadDir,
 		IgnoreDependencyErrors:     false,
 		IgnoreExternalDependencies: false,
-		Writer:                     os.Stdout,
-		ErrWriter:                  os.Stderr,
-		MaxFoldersToCheck:          DEFAULT_MAX_FOLDERS_TO_CHECK,
-		AutoRetry:                  true,
-		MaxRetryAttempts:           DEFAULT_MAX_RETRY_ATTEMPTS,
-		Sleep:                      DEFAULT_SLEEP,
-		RetryableErrors:            util.CloneStringList(RETRYABLE_ERRORS),
-		ExcludeDirs:                []string{},
-		IncludeDirs:                []string{},
-		Check:                      false,
+		Writer:            os.Stdout,
+		ErrWriter:         os.Stderr,
+		MaxFoldersToCheck: DEFAULT_MAX_FOLDERS_TO_CHECK,
+		AutoRetry:         true,
+		MaxRetryAttempts:  DEFAULT_MAX_RETRY_ATTEMPTS,
+		Sleep:             DEFAULT_SLEEP,
+		RetryableErrors:   util.CloneStringList(RETRYABLE_ERRORS),
+		ExcludeDirs:       []string{},
+		IncludeDirs:       []string{},
+		Check:             false,
 		RunTerragrunt: func(terragruntOptions *TerragruntOptions) error {
 			return errors.WithStackTrace(RunTerragruntCommandNotSet)
 		},
@@ -205,16 +208,16 @@ func (terragruntOptions *TerragruntOptions) Clone(terragruntConfigPath string) *
 		IamRole:                    terragruntOptions.IamRole,
 		IgnoreDependencyErrors:     terragruntOptions.IgnoreDependencyErrors,
 		IgnoreExternalDependencies: terragruntOptions.IgnoreExternalDependencies,
-		Writer:                     terragruntOptions.Writer,
-		ErrWriter:                  terragruntOptions.ErrWriter,
-		MaxFoldersToCheck:          terragruntOptions.MaxFoldersToCheck,
-		AutoRetry:                  terragruntOptions.AutoRetry,
-		MaxRetryAttempts:           terragruntOptions.MaxRetryAttempts,
-		Sleep:                      terragruntOptions.Sleep,
-		RetryableErrors:            util.CloneStringList(terragruntOptions.RetryableErrors),
-		ExcludeDirs:                terragruntOptions.ExcludeDirs,
-		IncludeDirs:                terragruntOptions.IncludeDirs,
-		RunTerragrunt:              terragruntOptions.RunTerragrunt,
+		Writer:            terragruntOptions.Writer,
+		ErrWriter:         terragruntOptions.ErrWriter,
+		MaxFoldersToCheck: terragruntOptions.MaxFoldersToCheck,
+		AutoRetry:         terragruntOptions.AutoRetry,
+		MaxRetryAttempts:  terragruntOptions.MaxRetryAttempts,
+		Sleep:             terragruntOptions.Sleep,
+		RetryableErrors:   util.CloneStringList(terragruntOptions.RetryableErrors),
+		ExcludeDirs:       terragruntOptions.ExcludeDirs,
+		IncludeDirs:       terragruntOptions.IncludeDirs,
+		RunTerragrunt:     terragruntOptions.RunTerragrunt,
 	}
 }