mostly remove OS_ARCH knowledge from discovery

Since the command package also needs to know about the specific OS_ARCH
directories, remove the logic fom the discovery package.

This doesn't completely remove the knowledge of the path from discovery,
in order to maintain the current behavior of skipping legacy plugin
names within a new-style path.

plugin/discovery/find.go

@@ -4,11 +4,14 @@ import (
 	"io/ioutil"
 	"log"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strings"
 )
 
-const machineName = runtime.GOOS + "_" + runtime.GOARCH
+// Store the machine name for excluding legacy plugins in new-style directories.
+// This is a var to override in testing
+var machineName = runtime.GOOS + "_" + runtime.GOARCH
 
 // FindPlugins looks in the given directories for files whose filenames
 // suggest that they are plugins of the given kind (e.g. "provider") and
@@ -41,66 +44,53 @@ func FindPluginPaths(kind string, dirs []string) []string {
 	// This is just a thin wrapper around findPluginPaths so that we can
 	// use the latter in tests with a fake machineName so we can use our
 	// test fixtures.
-	return findPluginPaths(kind, machineName, dirs)
+	return findPluginPaths(kind, dirs)
 }
 
-func findPluginPaths(kind string, machineName string, dirs []string) []string {
+func findPluginPaths(kind string, dirs []string) []string {
+	hasMachineSuffix := regexp.MustCompile(machineName + "/?").MatchString
+
 	prefix := "terraform-" + kind + "-"
 
 	ret := make([]string, 0, len(dirs))
 
-	for _, baseDir := range dirs {
-		baseItems, err := ioutil.ReadDir(baseDir)
+	for _, dir := range dirs {
+		items, err := ioutil.ReadDir(dir)
 		if err != nil {
 			// Ignore missing dirs, non-dirs, etc
 			continue
 		}
 
-		log.Printf("[DEBUG] checking for plugins in %q", baseDir)
+		log.Printf("[DEBUG] checking for plugins in %q", dir)
 
-		for _, item := range baseItems {
+		isMachineDir := hasMachineSuffix(dir)
+
+		for _, item := range items {
 			fullName := item.Name()
 
-			if fullName == machineName && item.Mode().IsDir() {
-				// Current-style $GOOS-$GOARCH directory prefix
-				machineDir := filepath.Join(baseDir, machineName)
-				machineItems, err := ioutil.ReadDir(machineDir)
-				if err != nil {
-					continue
-				}
-
-				log.Printf("[DEBUG] checking for plugins in %q", machineDir)
-
-				for _, item := range machineItems {
-					fullName := item.Name()
-
-					if !strings.HasPrefix(fullName, prefix) {
-						continue
-					}
-
-					// New-style paths must have a version segment in filename
-					if !strings.Contains(strings.ToLower(fullName), "_v") {
-						continue
-					}
-
-					absPath, err := filepath.Abs(filepath.Join(machineDir, fullName))
-					if err != nil {
-						continue
-					}
-
-					log.Printf("[DEBUG] found plugin %q", fullName)
-
-					ret = append(ret, filepath.Clean(absPath))
-				}
-
+			if !strings.HasPrefix(fullName, prefix) {
+				log.Printf("[DEBUG] skipping %q, not a plugin", fullName)
 				continue
 			}
 
-			// FIXME: we pass in GOOS_GOARCH paths directly, so these may not be "legacy"
-			if strings.HasPrefix(fullName, prefix) {
-				// Legacy style with files directly in the base directory
-				absPath, err := filepath.Abs(filepath.Join(baseDir, fullName))
+			// New-style paths must have a version segment in filename
+			if strings.Contains(strings.ToLower(fullName), "_v") {
+				absPath, err := filepath.Abs(filepath.Join(dir, fullName))
 				if err != nil {
+					log.Printf("[ERROR] plugin filepath error: %s", err)
+					continue
+				}
+
+				log.Printf("[DEBUG] found plugin %q", fullName)
+				ret = append(ret, filepath.Clean(absPath))
+				continue
+			}
+
+			if !isMachineDir {
+				// Legacy style with files directly in the base directory
+				absPath, err := filepath.Abs(filepath.Join(dir, fullName))
+				if err != nil {
+					log.Printf("[ERROR] plugin filepath error: %s", err)
 					continue
 				}
 

plugin/discovery/find_test.go

@@ -7,12 +7,15 @@ import (
 	"testing"
 )
 
+func init() {
+	machineName = "mockos_mockarch"
+}
+
 func TestFindPluginPaths(t *testing.T) {
 	got := findPluginPaths(
 		"foo",
-		"mockos_mockarch",
 		[]string{
-			"test-fixtures/current-style-plugins",
+			"test-fixtures/current-style-plugins/mockos_mockarch",
 			"test-fixtures/legacy-style-plugins",
 			"test-fixtures/non-existent",
 			"test-fixtures/not-a-dir",