Count Meta-Parameter

config/config.go

@@ -31,6 +31,7 @@ type ProviderConfig struct {
 type Resource struct {
 	Name      string
 	Type      string
+	Count     int
 	RawConfig *RawConfig
 }
 

config/loader_libucl.go

@@ -253,6 +253,9 @@ func loadResourcesLibucl(o *libucl.Object) ([]*Resource, error) {
 					err)
 			}
 
+			// Remove the "count" from the config, since we treat that special
+			delete(config, "count")
+
 			rawConfig, err := NewRawConfig(config)
 			if err != nil {
 				return nil, fmt.Errorf(
@@ -262,9 +265,24 @@ func loadResourcesLibucl(o *libucl.Object) ([]*Resource, error) {
 					err)
 			}
 
+			// If we have a count, then figure it out
+			var count int = 1
+			if o := r.Get("count"); o != nil {
+				err = o.Decode(&count)
+				o.Close()
+				if err != nil {
+					return nil, fmt.Errorf(
+						"Error parsing count for %s[%s]: %s",
+						t.Key(),
+						r.Key(),
+						err)
+				}
+			}
+
 			result = append(result, &Resource{
 				Name:      r.Key(),
 				Type:      t.Key(),
+				Count:     count,
 				RawConfig: rawConfig,
 			})
 		}

config/loader_test.go

@@ -145,9 +145,10 @@ func resourcesStr(rs []*Resource) string {
 	result := ""
 	for _, r := range rs {
 		result += fmt.Sprintf(
-			"%s[%s]\n",
+			"%s[%s] (x%d)\n",
 			r.Type,
-			r.Name)
+			r.Name,
+			r.Count)
 
 		ks := make([]string, 0, len(r.RawConfig.Raw))
 		for k, _ := range r.RawConfig.Raw {
@@ -229,14 +230,18 @@ do
 `
 
 const basicResourcesStr = `
-aws_security_group[firewall]
-aws_instance[web]
+aws_security_group[firewall] (x5)
+aws_instance[web] (x1)
   ami
   network_interface
   security_groups
   vars
     resource: aws_security_group.firewall.foo
     user: var.foo
+aws_instance[db] (x1)
+  security_groups
+  vars
+    resource: aws_security_group.firewall.*.id
 `
 
 const basicVariablesStr = `
@@ -251,8 +256,8 @@ aws
 `
 
 const importResourcesStr = `
-aws_security_group[db]
-aws_security_group[web]
+aws_security_group[db] (x1)
+aws_security_group[web] (x1)
 `
 
 const importVariablesStr = `

config/test-fixtures/basic.tf

@@ -13,6 +13,7 @@ provider "do" {
 }
 
 resource "aws_security_group" "firewall" {
+    count = 5
 }
 
 resource aws_instance "web" {
@@ -27,3 +28,7 @@ resource aws_instance "web" {
         description = "Main network interface"
     }
 }
+
+resource "aws_instance" "db" {
+    security_groups = "${aws_security_group.firewall.*.id}"
+}

config/variable.go

@@ -13,7 +13,7 @@ import (
 var varRegexp *regexp.Regexp
 
 func init() {
-	varRegexp = regexp.MustCompile(`(?i)(\$+)\{([-.a-z0-9_]+)\}`)
+	varRegexp = regexp.MustCompile(`(?i)(\$+)\{([*-.a-z0-9_]+)\}`)
 }
 
 // ReplaceVariables takes a configuration and a mapping of variables

config/variable_test.go

@@ -87,6 +87,22 @@ func TestVariableDetectWalker_resource(t *testing.T) {
 	}
 }
 
+func TestVariableDetectWalker_resourceMulti(t *testing.T) {
+	w := new(variableDetectWalker)
+
+	str := `foo ${ec2.foo.*.bar}`
+	if err := w.Primitive(reflect.ValueOf(str)); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if len(w.Variables) != 1 {
+		t.Fatalf("bad: %#v", w.Variables)
+	}
+	if w.Variables["ec2.foo.*.bar"].(*ResourceVariable).FullKey() != "ec2.foo.*.bar" {
+		t.Fatalf("bad: %#v", w.Variables)
+	}
+}
+
 func TestVariableDetectWalker_bad(t *testing.T) {
 	w := new(variableDetectWalker)
 

depgraph/graph.go

@@ -9,6 +9,7 @@ import (
 	"bytes"
 	"fmt"
 	"sort"
+	"strings"
 	"sync"
 
 	"github.com/hashicorp/terraform/digraph"
@@ -42,7 +43,34 @@ type ValidateError struct {
 }
 
 func (v *ValidateError) Error() string {
-	return "The depedency graph is not valid"
+	var msgs []string
+
+	if v.MissingRoot {
+		msgs = append(msgs, "The graph has no single root")
+	}
+
+	for _, n := range v.Unreachable {
+		msgs = append(msgs, fmt.Sprintf(
+			"Unreachable node: %s", n.Name))
+	}
+
+	for _, c := range v.Cycles {
+		cycleNodes := make([]string, len(c))
+		for i, n := range c {
+			cycleNodes[i] = n.Name
+		}
+
+		msgs = append(msgs, fmt.Sprintf(
+			"Cycle: %s", strings.Join(cycleNodes, " -> ")))
+	}
+
+	for i, m := range msgs {
+		msgs[i] = fmt.Sprintf("* %s", m)
+	}
+
+	return fmt.Sprintf(
+		"The dependency graph is not valid:\n\n%s",
+		strings.Join(msgs, "\n"))
 }
 
 // ConstraintError is used to return detailed violation

terraform/context.go

@@ -3,6 +3,7 @@ package terraform
 import (
 	"fmt"
 	"log"
+	"strings"
 	"sync"
 	"sync/atomic"
 
@@ -509,6 +510,9 @@ func (c *Context) genericWalkFn(
 		vars[fmt.Sprintf("var.%s", k)] = v
 	}
 
+	// This will keep track of the counts of multi-count resources
+	counts := make(map[string]int)
+
 	// This will keep track of whether we're stopped or not
 	var stop uint32 = 0
 
@@ -523,8 +527,20 @@ func (c *Context) genericWalkFn(
 			return nil
 		}
 
+		// Calculate any aggregate interpolated variables if we have to.
+		// Aggregate variables (such as "test_instance.foo.*.id") are not
+		// pre-computed since the fanout would be expensive. We calculate
+		// them on-demand here.
+		computeAggregateVars(&l, n, counts, vars)
+
 		switch m := n.Meta.(type) {
 		case *GraphNodeResource:
+		case *GraphNodeResourceMeta:
+			// Record the count and then just ignore
+			l.Lock()
+			counts[m.ID] = m.Count
+			l.Unlock()
+			return nil
 		case *GraphNodeResourceProvider:
 			var rc *ResourceConfig
 			if m.Config != nil {
@@ -543,6 +559,8 @@ func (c *Context) genericWalkFn(
 			}
 
 			return nil
+		default:
+			panic(fmt.Sprintf("unknown graph node: %#v", n.Meta))
 		}
 
 		rn := n.Meta.(*GraphNodeResource)
@@ -603,3 +621,68 @@ func (c *Context) genericWalkFn(
 		return nil
 	}
 }
+
+func computeAggregateVars(
+	l *sync.RWMutex,
+	n *depgraph.Noun,
+	cs map[string]int,
+	vs map[string]string) {
+	var ivars map[string]config.InterpolatedVariable
+	switch m := n.Meta.(type) {
+	case *GraphNodeResource:
+		if m.Config != nil {
+			ivars = m.Config.RawConfig.Variables
+		}
+	case *GraphNodeResourceProvider:
+		if m.Config != nil {
+			ivars = m.Config.RawConfig.Variables
+		}
+	}
+	if len(ivars) == 0 {
+		return
+	}
+
+	for _, v := range ivars {
+		rv, ok := v.(*config.ResourceVariable)
+		if !ok {
+			continue
+		}
+
+		idx := strings.Index(rv.Field, ".")
+		if idx == -1 {
+			// It isn't an aggregated var
+			continue
+		}
+		if rv.Field[:idx] != "*" {
+			// It isn't an aggregated var
+			continue
+		}
+		field := rv.Field[idx+1:]
+
+		// Get the meta node so that we can determine the count
+		key := fmt.Sprintf("%s.%s", rv.Type, rv.Name)
+		l.RLock()
+		count, ok := cs[key]
+		l.RUnlock()
+		if !ok {
+			// This should never happen due to semantic checks
+			panic(fmt.Sprintf(
+				"non-existent resource variable access: %s\n\n%#v", key, rv))
+		}
+
+		var values []string
+		for i := 0; i < count; i++ {
+			key := fmt.Sprintf(
+				"%s.%s.%d.%s",
+				rv.Type,
+				rv.Name,
+				i,
+				field)
+			if v, ok := vs[key]; ok {
+				values = append(values, v)
+			}
+		}
+
+		vs[rv.FullKey()] = strings.Join(values, ",")
+	}
+}