config: LoadDir loads override files

config/import_tree.go

@@ -3,7 +3,6 @@ package config
 import (
 	"fmt"
 	"io"
-	"strings"
 )
 
 // configurable is an interface that must be implemented by any configuration
@@ -33,11 +32,15 @@ type fileLoaderFunc func(path string) (configurable, []string, error)
 // executes the proper fileLoaderFunc.
 func loadTree(root string) (*importTree, error) {
 	var f fileLoaderFunc
-	if strings.HasSuffix(root, ".tf") {
+	switch ext(root) {
+	case ".tf":
+		fallthrough
+	case ".tf.json":
 		f = loadFileLibucl
-	} else if strings.HasSuffix(root, ".tf.json") {
-		f = loadFileLibucl
-	} else {
+	default:
+	}
+
+	if f == nil {
 		return nil, fmt.Errorf(
 			"%s: unknown configuration format. Use '.tf' or '.tf.json' extension",
 			root)

config/loader.go

@@ -2,7 +2,11 @@ package config
 
 import (
 	"fmt"
+	"io"
+	"os"
 	"path/filepath"
+	"sort"
+	"strings"
 )
 
 // Load loads the Terraform configuration from a given file.
@@ -30,20 +34,67 @@ func Load(path string) (*Config, error) {
 
 // LoadDir loads all the Terraform configuration files in a single
 // directory and merges them together.
-func LoadDir(path string) (*Config, error) {
-	matches, err := filepath.Glob(filepath.Join(path, "*.tf"))
+func LoadDir(root string) (*Config, error) {
+	var files, overrides []string
+
+	f, err := os.Open(root)
 	if err != nil {
 		return nil, err
 	}
 
-	if len(matches) == 0 {
+	err = nil
+	for err != io.EOF {
+		var fis []os.FileInfo
+		fis, err = f.Readdir(128)
+		if err != nil && err != io.EOF {
+			f.Close()
+			return nil, err
+		}
+
+		for _, fi := range fis {
+			// Ignore directories
+			if fi.IsDir() {
+				continue
+			}
+
+			// Only care about files that are valid to load
+			name := fi.Name()
+			extValue := ext(name)
+			if extValue == "" {
+				continue
+			}
+
+			// Determine if we're dealing with an override
+			nameNoExt := name[:len(name)-len(extValue)]
+			override := nameNoExt == "override" ||
+				strings.HasSuffix(nameNoExt, "_override")
+
+			path := filepath.Join(root, name)
+			if override {
+				overrides = append(overrides, path)
+			} else {
+				files = append(files, path)
+			}
+		}
+	}
+
+	// Close the directory, we're done with it
+	f.Close()
+
+	if len(files) == 0 {
 		return nil, fmt.Errorf(
 			"No Terraform configuration files found in directory: %s",
-			path)
+			root)
 	}
 
 	var result *Config
-	for _, f := range matches {
+
+	// Sort the files and overrides so we have a deterministic order
+	sort.Strings(files)
+	sort.Strings(overrides)
+
+	// Load all the regular files, append them to each other.
+	for _, f := range files {
 		c, err := Load(f)
 		if err != nil {
 			return nil, err
@@ -59,5 +110,30 @@ func LoadDir(path string) (*Config, error) {
 		}
 	}
 
+	// Load all the overrides, and merge them into the config
+	for _, f := range overrides {
+		c, err := Load(f)
+		if err != nil {
+			return nil, err
+		}
+
+		result, err = Merge(result, c)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	return result, nil
 }
+
+// Ext returns the Terraform configuration extension of the given
+// path, or a blank string if it is an invalid function.
+func ext(path string) string {
+	if strings.HasSuffix(path, ".tf") {
+		return ".tf"
+	} else if strings.HasSuffix(path, ".tf.json") {
+		return ".tf.json"
+	} else {
+		return ""
+	}
+}

config/loader_test.go

@@ -171,6 +171,37 @@ func TestLoadDir_noMerge(t *testing.T) {
 	}
 }
 
+func TestLoadDir_override(t *testing.T) {
+	c, err := LoadDir(filepath.Join(fixtureDir, "dir-override"))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if c == nil {
+		t.Fatal("config should not be nil")
+	}
+
+	actual := variablesStr(c.Variables)
+	if actual != strings.TrimSpace(dirOverrideVariablesStr) {
+		t.Fatalf("bad:\n%s", actual)
+	}
+
+	actual = providerConfigsStr(c.ProviderConfigs)
+	if actual != strings.TrimSpace(dirOverrideProvidersStr) {
+		t.Fatalf("bad:\n%s", actual)
+	}
+
+	actual = resourcesStr(c.Resources)
+	if actual != strings.TrimSpace(dirOverrideResourcesStr) {
+		t.Fatalf("bad:\n%s", actual)
+	}
+
+	actual = outputsStr(c.Outputs)
+	if actual != strings.TrimSpace(dirOverrideOutputsStr) {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func outputsStr(os []*Output) string {
 	ns := make([]string, 0, len(os))
 	m := make(map[string]*Output)
@@ -503,6 +534,42 @@ foo
   bar
 `
 
+const dirOverrideOutputsStr = `
+web_ip
+  vars
+    resource: aws_instance.web.private_ip
+`
+
+const dirOverrideProvidersStr = `
+aws
+  access_key
+  secret_key
+do
+  api_key
+  vars
+    user: var.foo
+`
+
+const dirOverrideResourcesStr = `
+aws_instance[db] (x1)
+  ami
+  security_groups
+aws_instance[web] (x1)
+  ami
+  network_interface
+  security_groups
+  vars
+    resource: aws_security_group.firewall.foo
+    user: var.foo
+aws_security_group[firewall] (x5)
+`
+
+const dirOverrideVariablesStr = `
+foo
+  bar
+  bar
+`
+
 const importProvidersStr = `
 aws
   bar

config/test-fixtures/dir-override/one.tf

@@ -0,0 +1,17 @@
+variable "foo" {
+    default = "bar";
+    description = "bar";
+}
+
+provider "aws" {
+  access_key = "foo";
+  secret_key = "bar";
+}
+
+resource "aws_instance" "db" {
+    security_groups = "${aws_security_group.firewall.*.id}"
+}
+
+output "web_ip" {
+    value = "${aws_instance.web.private_ip}"
+}

config/test-fixtures/dir-override/override.tf.json

@@ -0,0 +1,10 @@
+{
+    "resource": {
+        "aws_instance": {
+            "db": {
+                "ami": "foo",
+                "security_groups": ""
+            }
+        }
+    }
+}

config/test-fixtures/dir-override/two.tf

@@ -0,0 +1,20 @@
+provider "do" {
+  api_key = "${var.foo}";
+}
+
+resource "aws_security_group" "firewall" {
+    count = 5
+}
+
+resource aws_instance "web" {
+    ami = "${var.foo}"
+    security_groups = [
+        "foo",
+        "${aws_security_group.firewall.foo}"
+    ]
+
+    network_interface {
+        device_index = 0
+        description = "Main network interface"
+    }
+}