Merge pull request #33 from hashicorp/f-depends

DependsOn 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.
@@ -154,6 +155,17 @@ func (c *Config) Validate() error {
 	}
 	dupped = nil
 
+	// Make sure all dependsOn are valid in resources
+	for n, r := range resources {
+		for _, d := range r.DependsOn {
+			if _, ok := resources[d]; !ok {
+				errs = append(errs, fmt.Errorf(
+					"%s: resource depends on non-existent resource '%s'",
+					n, d))
+			}
+		}
+	}
+
 	for source, vs := range vars {
 		for _, v := range vs {
 			rv, ok := v.(*ResourceVariable)

config/config_test.go

@@ -16,6 +16,13 @@ func TestConfigValidate(t *testing.T) {
 	}
 }
 
+func TestConfigValidate_badDependsOn(t *testing.T) {
+	c := testConfig(t, "validate-bad-depends-on")
+	if err := c.Validate(); err == nil {
+		t.Fatal("should not be valid")
+	}
+}
+
 func TestConfigValidate_badMultiResource(t *testing.T) {
 	c := testConfig(t, "validate-bad-multi-resource")
 	if err := c.Validate(); err == nil {

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": {

config/test-fixtures/validate-bad-depends-on/main.tf

@@ -0,0 +1,3 @@
+resource "aws_instance" "web" {
+    depends_on = ["aws_instance.db"]
+}

config/test-fixtures/validate-good/main.tf

@@ -32,4 +32,6 @@ resource aws_instance "web" {
         device_index = 0
         description = "Main network interface"
     }
+
+    depends_on = ["aws_security_group.firewall"]
 }

terraform/graph.go

@@ -106,6 +106,9 @@ func Graph(opts *GraphOpts) (*depgraph.Graph, error) {
 	// and no dependencies.
 	graphAddConfigResources(g, opts.Config, opts.State)
 
+	// Add explicit dependsOn dependencies to the graph
+	graphAddExplicitDeps(g)
+
 	// Next, add the state orphans if we have any
 	if opts.State != nil {
 		graphAddOrphans(g, opts.Config, opts.State)
@@ -377,6 +380,48 @@ func graphAddDiff(g *depgraph.Graph, d *Diff) error {
 	return nil
 }
 
+// graphAddExplicitDeps adds the dependencies to the graph for the explicit
+// dependsOn configurations.
+func graphAddExplicitDeps(g *depgraph.Graph) {
+	depends := false
+
+	rs := make(map[string]*depgraph.Noun)
+	for _, n := range g.Nouns {
+		rn, ok := n.Meta.(*GraphNodeResource)
+		if !ok {
+			continue
+		}
+
+		rs[rn.Config.Id()] = n
+		if len(rn.Config.DependsOn) > 0 {
+			depends = true
+		}
+	}
+
+	// If we didn't have any dependsOn, just return
+	if !depends {
+		return
+	}
+
+	for _, n1 := range rs {
+		rn1 := n1.Meta.(*GraphNodeResource)
+		for _, d := range rn1.Config.DependsOn {
+			for _, n2 := range rs {
+				rn2 := n2.Meta.(*GraphNodeResource)
+				if rn2.Config.Id() != d {
+					continue
+				}
+
+				n1.Deps = append(n1.Deps, &depgraph.Dependency{
+					Name:   d,
+					Source: n1,
+					Target: n2,
+				})
+			}
+		}
+	}
+}
+
 // graphAddMissingResourceProviders adds GraphNodeResourceProvider nodes for
 // the resources that do not have an explicit resource provider specified
 // because no provider configuration was given.

terraform/graph_test.go

@@ -51,6 +51,21 @@ func TestGraph_cycle(t *testing.T) {
 	}
 }
 
+func TestGraph_dependsOn(t *testing.T) {
+	config := testConfig(t, "graph-depends-on")
+
+	g, err := Graph(&GraphOpts{Config: config})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphDependsStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 func TestGraph_state(t *testing.T) {
 	config := testConfig(t, "graph-basic")
 	state := &State{
@@ -347,6 +362,16 @@ root
   root -> aws_load_balancer.weblb
 `
 
+const testTerraformGraphDependsStr = `
+root: root
+aws_instance.db
+  aws_instance.db -> aws_instance.web
+aws_instance.web
+root
+  root -> aws_instance.db
+  root -> aws_instance.web
+`
+
 const testTerraformGraphDiffStr = `
 root: root
 aws_instance.foo

terraform/test-fixtures/graph-depends-on/main.tf

@@ -0,0 +1,5 @@
+resource "aws_instance" "web" {}
+
+resource "aws_instance" "db" {
+	depends_on = ["aws_instance.web"]
+}