MM-10702 Moving plugins to use hashicorp go-plugin. (#8978)

* Moving plugins to use hashicorp go-plugin.

* Tweaks from feedback.

plugin/supervisor_test.go

@@ -0,0 +1,148 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package plugin
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/mattermost/mattermost-server/mlog"
+	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/plugin/plugintest"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSupervisor(t *testing.T) {
+	for name, f := range map[string]func(*testing.T){
+		"Supervisor":                           testSupervisor,
+		"Supervisor_InvalidExecutablePath":     testSupervisor_InvalidExecutablePath,
+		"Supervisor_NonExistentExecutablePath": testSupervisor_NonExistentExecutablePath,
+		"Supervisor_StartTimeout":              testSupervisor_StartTimeout,
+	} {
+		t.Run(name, f)
+	}
+}
+
+func CompileGo(t *testing.T, sourceCode, outputPath string) {
+	dir, err := ioutil.TempDir(".", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+	require.NoError(t, ioutil.WriteFile(filepath.Join(dir, "main.go"), []byte(sourceCode), 0600))
+	cmd := exec.Command("go", "build", "-o", outputPath, "main.go")
+	cmd.Dir = dir
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	require.NoError(t, cmd.Run())
+}
+
+func testSupervisor(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	backend := filepath.Join(dir, "backend.exe")
+	CompileGo(t, `
+		package main
+
+		import (
+			"github.com/mattermost/mattermost-server/plugin"
+		)
+
+		type MyPlugin struct {
+			plugin.MattermostPlugin
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+	`, backend)
+
+	ioutil.WriteFile(filepath.Join(dir, "plugin.json"), []byte(`{"id": "foo", "backend": {"executable": "backend.exe"}}`), 0600)
+
+	bundle := model.BundleInfoForPath(dir)
+	var api plugintest.API
+	api.On("LoadPluginConfiguration", mock.Anything).Return(nil)
+	log := mlog.NewLogger(&mlog.LoggerConfiguration{
+		EnableConsole: true,
+		ConsoleJson:   true,
+		ConsoleLevel:  "error",
+		EnableFile:    false,
+	})
+	supervisor, err := NewSupervisor(bundle, log, &api)
+	require.NoError(t, err)
+	supervisor.Shutdown()
+}
+
+func testSupervisor_InvalidExecutablePath(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	ioutil.WriteFile(filepath.Join(dir, "plugin.json"), []byte(`{"id": "foo", "backend": {"executable": "/foo/../../backend.exe"}}`), 0600)
+
+	bundle := model.BundleInfoForPath(dir)
+	log := mlog.NewLogger(&mlog.LoggerConfiguration{
+		EnableConsole: true,
+		ConsoleJson:   true,
+		ConsoleLevel:  "error",
+		EnableFile:    false,
+	})
+	supervisor, err := NewSupervisor(bundle, log, nil)
+	assert.Nil(t, supervisor)
+	assert.Error(t, err)
+}
+
+func testSupervisor_NonExistentExecutablePath(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	ioutil.WriteFile(filepath.Join(dir, "plugin.json"), []byte(`{"id": "foo", "backend": {"executable": "thisfileshouldnotexist"}}`), 0600)
+
+	bundle := model.BundleInfoForPath(dir)
+	log := mlog.NewLogger(&mlog.LoggerConfiguration{
+		EnableConsole: true,
+		ConsoleJson:   true,
+		ConsoleLevel:  "error",
+		EnableFile:    false,
+	})
+	supervisor, err := NewSupervisor(bundle, log, nil)
+	require.Error(t, err)
+	require.Nil(t, supervisor)
+}
+
+// If plugin development goes really wrong, let's make sure plugin activation won't block forever.
+func testSupervisor_StartTimeout(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	backend := filepath.Join(dir, "backend.exe")
+	CompileGo(t, `
+		package main
+
+		func main() {
+			for {
+			}
+		}
+	`, backend)
+
+	ioutil.WriteFile(filepath.Join(dir, "plugin.json"), []byte(`{"id": "foo", "backend": {"executable": "backend.exe"}}`), 0600)
+
+	bundle := model.BundleInfoForPath(dir)
+	log := mlog.NewLogger(&mlog.LoggerConfiguration{
+		EnableConsole: true,
+		ConsoleJson:   true,
+		ConsoleLevel:  "error",
+		EnableFile:    false,
+	})
+	supervisor, err := NewSupervisor(bundle, log, nil)
+	require.Error(t, err)
+	require.Nil(t, supervisor)
+}