config: depends_on meta-parameter

config/config.go

@@ -42,6 +42,7 @@ type Resource struct {
 	Count        int
 	RawConfig    *RawConfig
 	Provisioners []*Provisioner
+	DependsOn    []string
 }
 
 // Provisioner is a configured provisioner step on a resource.

config/loader_libucl.go

@@ -352,16 +352,11 @@ func loadResourcesLibucl(o *libucl.Object) ([]*Resource, error) {
 					err)
 			}
 
-			// Remove the "count" from the config, since we treat that special
+			// Remove the fields we handle specially
-			delete(config, "count")
-
-			// Delete the "provisioner" section from the config since
-			// that is treated specially.
-			delete(config, "provisioner")
-
-			// Delete the "connection" section since we handle that
-			// seperately
 			delete(config, "connection")
+			delete(config, "count")
+			delete(config, "depends_on")
+			delete(config, "provisioner")
 
 			rawConfig, err := NewRawConfig(config)
 			if err != nil {
@@ -401,6 +396,20 @@ func loadResourcesLibucl(o *libucl.Object) ([]*Resource, error) {
 				}
 			}
 
+			// If we have depends fields, then add those in
+			var dependsOn []string
+			if deps := r.Get("depends_on"); deps != nil {
+				err := deps.Decode(&dependsOn)
+				deps.Close()
+				if err != nil {
+					return nil, fmt.Errorf(
+						"Error reading depends_on for %s[%s]: %s",
+						t.Key(),
+						r.Key(),
+						err)
+				}
+			}
+
 			// If we have provisioners, then parse those out
 			var provisioners []*Provisioner
 			if po := r.Get("provisioner"); po != nil {
@@ -422,6 +431,7 @@ func loadResourcesLibucl(o *libucl.Object) ([]*Resource, error) {
 				Count:        count,
 				RawConfig:    rawConfig,
 				Provisioners: provisioners,
+				DependsOn:    dependsOn,
 			})
 		}
 	}

config/loader_test.go

@@ -393,6 +393,13 @@ func resourcesStr(rs []*Resource) string {
 			}
 		}
 
+		if len(r.DependsOn) > 0 {
+			result += fmt.Sprintf("  dependsOn\n")
+			for _, d := range r.DependsOn {
+				result += fmt.Sprintf("    %s\n", d)
+			}
+		}
+
 		if len(r.RawConfig.Variables) > 0 {
 			result += fmt.Sprintf("  vars\n")
 
@@ -479,6 +486,8 @@ do
 const basicResourcesStr = `
 aws_instance[db] (x1)
   security_groups
+  dependsOn
+    aws_instance.web
   vars
     resource: aws_security_group.firewall.*.id
 aws_instance[web] (x1)

config/test-fixtures/basic.tf

@@ -31,6 +31,8 @@ resource aws_instance "web" {
 
 resource "aws_instance" "db" {
     security_groups = "${aws_security_group.firewall.*.id}"
+
+    depends_on = ["aws_instance.web"]
 }
 
 output "web_ip" {

config/test-fixtures/basic.tf.json

@@ -20,7 +20,8 @@
     "resource": {
         "aws_instance": {
             "db": {
-                "security_groups": ["${aws_security_group.firewall.*.id}"]
+                "security_groups": ["${aws_security_group.firewall.*.id}"],
+                "depends_on": ["aws_instance.web"]
             },
 
             "web": {