Merge pull request #540 from lorengordon/hook-init-once

Adds options attribute to track state of the terraform command

README.md

@@ -1670,6 +1670,11 @@ that will be called either before or after execution of the `terraform` command.
 
 The `commands` array specifies the `terraform` commands that will trigger the execution of the hook.
 
+Because Terragrunt uses `terraform init` in two different ways, use the special command `init-from-module`
+to execute hooks only when retrieving the terraform source. The command `init` will execute hooks only when
+executing Terragrunt's [Auto-Init](#auto-init) capability, which includes configuring the backend, retrieving
+provider plugins, and remote modules specified within the root module.
+
 It is possible to use the [interpolation syntax](#interpolation-syntax) defined above in the `execute` array of the hooks.
 
 The `run_on_error` parameter allows you to specify whether you still want this hook to execute if an error has been encountered with the earlier execution of another hook OR with the execution of the `terraform` command iteself.  
@@ -1703,6 +1708,11 @@ terragrunt = {
       execute = ["echo", "Baz"]
       run_on_error = true
     }
+
+    after_hook "init_from_module" {
+      commands = ["init-from-module"]
+      execute = ["cp", "${get_parent_tfvars_dir()}/foo.tf", "."]
+    }
   }
 }
 ```

cli/args.go

@@ -96,6 +96,7 @@ func parseTerragruntOptionsFromArgs(args []string, writer, errWriter io.Writer)
 	opts.AutoInit = !parseBooleanArg(args, OPT_TERRAGRUNT_NO_AUTO_INIT, os.Getenv("TERRAGRUNT_AUTO_INIT") == "false")
 	opts.NonInteractive = parseBooleanArg(args, OPT_NON_INTERACTIVE, os.Getenv("TF_INPUT") == "false" || os.Getenv("TF_INPUT") == "0")
 	opts.TerraformCliArgs = filterTerragruntArgs(args)
+	opts.TerraformCommand = util.FirstArg(opts.TerraformCliArgs)
 	opts.WorkingDir = filepath.ToSlash(workingDir)
 	opts.DownloadDir = filepath.ToSlash(downloadDir)
 	opts.Logger = util.CreateLoggerWithWriter(errWriter, "")
@@ -113,7 +114,7 @@ func parseTerragruntOptionsFromArgs(args []string, writer, errWriter io.Writer)
 
 func filterTerraformExtraArgs(terragruntOptions *options.TerragruntOptions, terragruntConfig *config.TerragruntConfig) []string {
 	out := []string{}
-	cmd := firstArg(terragruntOptions.TerraformCliArgs)
+	cmd := util.FirstArg(terragruntOptions.TerraformCliArgs)
 
 	for _, arg := range terragruntConfig.Terraform.ExtraArgs {
 		for _, arg_cmd := range arg.Commands {
@@ -208,24 +209,6 @@ func parseStringArg(args []string, argName string, defaultValue string) (string,
 	return defaultValue, nil
 }
 
-// A convenience method that returns the first item (0th index) in the given list or an empty string if this is an
-// empty list
-func firstArg(args []string) string {
-	if len(args) > 0 {
-		return args[0]
-	}
-	return ""
-}
-
-// A convenience method that returns the second item (1st index) in the given list or an empty string if this is a
-// list that has less than 2 items in it
-func secondArg(args []string) string {
-	if len(args) > 1 {
-		return args[1]
-	}
-	return ""
-}
-
 // Custom error types
 
 type ArgMissingValue string

cli/cli_app.go

@@ -43,6 +43,7 @@ const CMD_OUTPUT_ALL = "output-all"
 const CMD_VALIDATE_ALL = "validate-all"
 
 const CMD_INIT = "init"
+const CMD_INIT_FROM_MODULE = "init-from-module"
 
 // CMD_SPIN_UP is deprecated.
 const CMD_SPIN_UP = "spin-up"
@@ -290,7 +291,7 @@ func shouldRunHook(hook config.Hook, terragruntOptions *options.TerragruntOption
 	//for the len(previousExecErrors) == 0 check that used to be here
 	multiError := errors.NewMultiError(previousExecErrors...)
 
-	return util.ListContainsElement(hook.Commands, terragruntOptions.TerraformCliArgs[0]) && (multiError == nil || hook.RunOnError)
+	return util.ListContainsElement(hook.Commands, terragruntOptions.TerraformCommand) && (multiError == nil || hook.RunOnError)
 }
 
 // Assume an IAM role, if one is specified, by making API calls to Amazon STS and setting the environment variables
@@ -322,7 +323,7 @@ func runTerragruntWithConfig(terragruntOptions *options.TerragruntOptions, terra
 		terragruntOptions.InsertTerraformCliArgs(filterTerraformExtraArgs(terragruntOptions, terragruntConfig)...)
 	}
 
-	if firstArg(terragruntOptions.TerraformCliArgs) == CMD_INIT {
+	if util.FirstArg(terragruntOptions.TerraformCliArgs) == CMD_INIT {
 		if err := prepareInitCommand(terragruntOptions, terragruntConfig, allowSourceDownload); err != nil {
 			return err
 		}
@@ -468,7 +469,7 @@ func prepareNonInitCommand(terragruntOptions *options.TerragruntOptions, terragr
 
 // Determines if 'terraform init' needs to be executed
 func needsInit(terragruntOptions *options.TerragruntOptions, terragruntConfig *config.TerragruntConfig) (bool, error) {
-	if util.ListContainsElement(TERRAFORM_COMMANDS_THAT_DO_NOT_NEED_INIT, firstArg(terragruntOptions.TerraformCliArgs)) {
+	if util.ListContainsElement(TERRAFORM_COMMANDS_THAT_DO_NOT_NEED_INIT, util.FirstArg(terragruntOptions.TerraformCliArgs)) {
 		return false, nil
 	}
 
@@ -506,14 +507,15 @@ func providersNeedInit(terragruntOptions *options.TerragruntOptions) bool {
 func runTerraformInit(terragruntOptions *options.TerragruntOptions, terragruntConfig *config.TerragruntConfig, terraformSource *TerraformSource) error {
 
 	// Prevent Auto-Init if the user has disabled it
-	if firstArg(terragruntOptions.TerraformCliArgs) != CMD_INIT && !terragruntOptions.AutoInit {
+	if util.FirstArg(terragruntOptions.TerraformCliArgs) != CMD_INIT && !terragruntOptions.AutoInit {
 		return errors.WithStackTrace(InitNeededButDisabled("Cannot continue because init is needed, but Auto-Init is disabled.  You must run 'terragrunt init' manually."))
 	}
 
 	// Need to clone the terragruntOptions, so the TerraformCliArgs can be configured to run the init command
 	initOptions := terragruntOptions.Clone(terragruntOptions.TerragruntConfigPath)
 	initOptions.TerraformCliArgs = []string{CMD_INIT}
 	initOptions.WorkingDir = terragruntOptions.WorkingDir
+	initOptions.TerraformCommand = CMD_INIT
 
 	// Don't pollute stdout with the stdout from Aoto Init
 	initOptions.Writer = initOptions.ErrWriter
@@ -533,6 +535,9 @@ func runTerraformInit(terragruntOptions *options.TerragruntOptions, terragruntCo
 		initOptions.AppendTerraformCliArgs("-get-plugins=false")
 		initOptions.AppendTerraformCliArgs("-backend=false")
 
+		// Set the TerraformCommand attribute to match hooks on `init-from-module`
+		initOptions.TerraformCommand = CMD_INIT_FROM_MODULE
+
 		v0_10_0, err := version.NewVersion("v0.10.0")
 		if err != nil {
 			return err
@@ -545,6 +550,7 @@ func runTerraformInit(terragruntOptions *options.TerragruntOptions, terragruntCo
 			// Terraform versions >= 0.10.0 specify the module source using the -from-module option
 			initOptions.AppendTerraformCliArgs("-from-module="+terraformSource.CanonicalSourceURL.String(), "-no-color")
 		}
+
 		initOptions.AppendTerraformCliArgs(terraformSource.DownloadDir)
 	}
 
@@ -618,7 +624,7 @@ func remoteStateNeedsInit(remoteState *remote.RemoteState, terragruntOptions *op
 
 	// We only configure remote state for the commands that use the tfstate files. We do not configure it for
 	// commands such as "get" or "version".
-	if remoteState != nil && util.ListContainsElement(TERRAFORM_COMMANDS_THAT_USE_STATE, firstArg(terragruntOptions.TerraformCliArgs)) {
+	if remoteState != nil && util.ListContainsElement(TERRAFORM_COMMANDS_THAT_USE_STATE, util.FirstArg(terragruntOptions.TerraformCliArgs)) {
 		return remoteState.NeedsInit(terragruntOptions)
 	}
 	return false, nil
@@ -703,7 +709,7 @@ func validateAll(terragruntOptions *options.TerragruntOptions) error {
 
 // checkProtectedModule checks if module is protected via the "prevent_destroy" flag
 func checkProtectedModule(terragruntOptions *options.TerragruntOptions, terragruntConfig *config.TerragruntConfig) error {
-	if firstArg(terragruntOptions.TerraformCliArgs) != "destroy" {
+	if util.FirstArg(terragruntOptions.TerraformCliArgs) != "destroy" {
 		return nil
 	}
 	if terragruntConfig.PreventDestroy {

configstack/stack.go

@@ -8,6 +8,7 @@ import (
 	"github.com/gruntwork-io/terragrunt/config"
 	"github.com/gruntwork-io/terragrunt/errors"
 	"github.com/gruntwork-io/terragrunt/options"
+	"github.com/gruntwork-io/terragrunt/util"
 	"sort"
 )
 
@@ -114,6 +115,7 @@ func FindStackInSubfolders(terragruntOptions *options.TerragruntOptions) (*Stack
 func (stack *Stack) setTerraformCommand(command []string) {
 	for _, module := range stack.Modules {
 		module.TerragruntOptions.TerraformCliArgs = append(command, module.TerragruntOptions.TerraformCliArgs...)
+		module.TerragruntOptions.TerraformCommand = util.FirstArg(command)
 	}
 }
 

options/options.go

@@ -30,6 +30,9 @@ type TerragruntOptions struct {
 	// Location of the terraform binary
 	TerraformPath string
 
+	// Current Terraform command being executed by Terragrunt
+	TerraformCommand string
+
 	// Version of terraform (obtained by running 'terraform version')
 	TerraformVersion *version.Version
 
@@ -97,6 +100,7 @@ func NewTerragruntOptions(terragruntConfigPath string) (*TerragruntOptions, erro
 	return &TerragruntOptions{
 		TerragruntConfigPath:   terragruntConfigPath,
 		TerraformPath:          "terraform",
+		TerraformCommand:       "",
 		AutoInit:               true,
 		NonInteractive:         false,
 		TerraformCliArgs:       []string{},
@@ -154,6 +158,7 @@ func (terragruntOptions *TerragruntOptions) Clone(terragruntConfigPath string) *
 	return &TerragruntOptions{
 		TerragruntConfigPath:   terragruntConfigPath,
 		TerraformPath:          terragruntOptions.TerraformPath,
+		TerraformCommand:       terragruntOptions.TerraformCommand,
 		TerraformVersion:       terragruntOptions.TerraformVersion,
 		AutoInit:               terragruntOptions.AutoInit,
 		NonInteractive:         terragruntOptions.NonInteractive,

test/fixture-hooks/init-once/backend.tf

@@ -0,0 +1,3 @@
+terraform {
+  backend "s3" {}
+}

test/fixture-hooks/init-once/base-module/main.tf

@@ -0,0 +1,7 @@
+data "template_file" "example" {
+  template = "hello, world"
+}
+
+output "example" {
+  value = "${data.template_file.example.rendered}"
+}

test/fixture-hooks/init-once/no-source-no-backend/main.tf

@@ -0,0 +1,7 @@
+data "template_file" "example" {
+  template = "hello, world"
+}
+
+output "example" {
+  value = "${data.template_file.example.rendered}"
+}

test/fixture-hooks/init-once/no-source-no-backend/terraform.tfvars

@@ -0,0 +1,17 @@
+terragrunt = {
+  terraform {
+    # Should NOT execute. With no source, init-from-module should never execute.
+    # If AFTER_INIT_FROM_MODULE_ONLY_ONCE is present in output, the test failed
+    after_hook "after_init_from_module" {
+      commands = ["init-from-module"]
+      execute = ["echo","AFTER_INIT_FROM_MODULE_ONLY_ONCE"]
+    }
+
+    # SHOULD execute
+    # If AFTER_INIT_ONLY_ONCE is not present exactly once in output, the test failed
+    after_hook "after_init" {
+      commands = ["init"]
+      execute = ["echo","AFTER_INIT_ONLY_ONCE"]
+    }
+  }
+}

test/fixture-hooks/init-once/no-source-with-backend/main.tf

@@ -0,0 +1,11 @@
+terraform {
+  backend "s3" {}
+}
+
+data "template_file" "example" {
+  template = "hello, world"  
+}
+
+output "example" {
+  value = "${data.template_file.example.rendered}"
+}

test/fixture-hooks/init-once/no-source-with-backend/terraform.tfvars

@@ -0,0 +1,27 @@
+terragrunt = {
+  remote_state {
+    backend = "s3"
+    config {
+      encrypt = true
+      bucket = "__FILL_IN_BUCKET_NAME__"
+      key = "terraform.tfstate"
+      region = "__FILL_IN_REGION__"
+    }
+  }
+
+  terraform {
+    # Should NOT execute. With no source, init-from-module should never execute.
+    # If AFTER_INIT_FROM_MODULE_ONLY_ONCE is present in output, the test failed
+    after_hook "after_init_from_module" {
+      commands = ["init-from-module"]
+      execute = ["echo","AFTER_INIT_FROM_MODULE_ONLY_ONCE"]
+    }
+
+    # SHOULD execute.
+    # If AFTER_INIT_ONLY_ONCE is not echoed exactly once, the test failed
+    after_hook "after_init" {
+      commands = ["init"]
+      execute = ["echo","AFTER_INIT_ONLY_ONCE"]
+    }
+  }
+}

test/fixture-hooks/init-once/with-source-no-backend/terraform.tfvars

@@ -0,0 +1,19 @@
+terragrunt = {
+  terraform {
+    source = "../base-module"
+
+    # SHOULD execute.
+    # If AFTER_INIT_FROM_MODULE_ONLY_ONCE is not echoed exactly once, the test failed
+    after_hook "after_init_from_module" {
+      commands = ["init-from-module"]
+      execute = ["echo","AFTER_INIT_FROM_MODULE_ONLY_ONCE"]
+    }
+
+    # SHOULD execute.
+    # If AFTER_INIT_ONLY_ONCE is not echoed exactly once, the test failed
+    after_hook "after_init" {
+      commands = ["init"]
+      execute = ["echo","AFTER_INIT_ONLY_ONCE"]
+    }
+  }
+}

test/fixture-hooks/init-once/with-source-with-backend/terraform.tfvars

@@ -0,0 +1,34 @@
+terragrunt = {
+  remote_state {
+    backend = "s3"
+    config {
+      encrypt = true
+      bucket = "__FILL_IN_BUCKET_NAME__"
+      key = "terraform.tfstate"
+      region = "__FILL_IN_REGION__"
+    }
+  }
+
+  terraform {
+    source = "../base-module"
+
+    after_hook "backend" {
+      commands = ["init-from-module"]
+      execute  = ["cp", "${get_tfvars_dir()}/../backend.tf", "."]
+    }
+
+    # SHOULD execute.
+    # If AFTER_INIT_FROM_MODULE_ONLY_ONCE is not echoed exactly once, the test failed
+    after_hook "after_init_from_module" {
+      commands = ["init-from-module"]
+      execute = ["echo","AFTER_INIT_FROM_MODULE_ONLY_ONCE"]
+    }
+
+    # SHOULD execute.
+    # If AFTER_INIT_ONLY_ONCE is not echoed exactly once, the test failed
+    after_hook "after_init" {
+      commands = ["init"]
+      execute = ["echo","AFTER_INIT_ONLY_ONCE"]
+    }
+  }
+}