From f59c71b35a3c671208bf2ceaa84e9be5a48929aa Mon Sep 17 00:00:00 2001
From: Kevin Nuckolls <kevin.nuckolls@gmail.com>
Date: Wed, 6 May 2015 10:58:42 -0500
Subject: [PATCH] works for apply, no tests yet

---
 command/apply.go | 10 +++++++---
 command/meta.go  |  8 ++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/command/apply.go b/command/apply.go
index f924c65ca..232b44b82 100644
--- a/command/apply.go
+++ b/command/apply.go
@@ -39,6 +39,7 @@ func (c *ApplyCommand) Run(args []string) int {
 		cmdFlags.BoolVar(&destroyForce, "force", false, "force")
 	}
 	cmdFlags.BoolVar(&refresh, "refresh", true, "refresh")
+	cmdFlags.IntVar(&c.Meta.parallelism, "parallelism", 0, "parallelism")
 	cmdFlags.StringVar(&c.Meta.statePath, "state", DefaultStateFilename, "path")
 	cmdFlags.StringVar(&c.Meta.stateOutPath, "state-out", "", "path")
 	cmdFlags.StringVar(&c.Meta.backupPath, "backup", "", "path")
@@ -94,9 +95,10 @@ func (c *ApplyCommand) Run(args []string) int {
 
 	// Build the context based on the arguments given
 	ctx, planned, err := c.Context(contextOpts{
-		Destroy:   c.Destroy,
-		Path:      configPath,
-		StatePath: c.Meta.statePath,
+		Destroy:     c.Destroy,
+		Path:        configPath,
+		StatePath:   c.Meta.statePath,
+		Parallelism: c.Meta.parallelism,
 	})
 	if err != nil {
 		c.Ui.Error(err.Error())
@@ -278,6 +280,8 @@ Options:
 
   -no-color              If specified, output won't contain any color.
 
+  -parallelism=#         Limit the number of concurrent operations.
+
   -refresh=true          Update state prior to checking for differences. This
                          has no effect if a plan file is given to apply.
 
diff --git a/command/meta.go b/command/meta.go
index 4c1c09afe..af4a52302 100644
--- a/command/meta.go
+++ b/command/meta.go
@@ -59,9 +59,13 @@ type Meta struct {
 	//
 	// backupPath is used to backup the state file before writing a modified
 	// version. It defaults to stateOutPath + DefaultBackupExtension
+	//
+	// parallelism is used to control the number of concurrent operations
+	// allowed when walking the graph
 	statePath    string
 	stateOutPath string
 	backupPath   string
+	parallelism  int
 }
 
 // initStatePaths is used to initialize the default values for
@@ -151,6 +155,7 @@ func (m *Meta) Context(copts contextOpts) (*terraform.Context, bool, error) {
 	}
 
 	opts.Module = mod
+	opts.Parallelism = copts.Parallelism
 	opts.State = state.State()
 	ctx := terraform.NewContext(opts)
 	return ctx, false, nil
@@ -430,4 +435,7 @@ type contextOpts struct {
 
 	// Set to true when running a destroy plan/apply.
 	Destroy bool
+
+	// Number of concurrent operations allowed
+	Parallelism int
 }