MM-14575 - Automatically serve static files for plugins (#10476)

* MM-14575 - Automatically serve static files for plugins
* Added static handler for plugin public files
* Added StaticFilesPath method to Environment for use by MainRouter
* Added "static_files" property to Manifest Server
* Added unit tests for these changes

* MM-14575: Adding comment for cache control value

* MM-14575: Moved Static Plugin Request handler to plugin_requests
* Updated testing

* MM-14575: Removing the StaticFiles from Manifest Server

* MM-14575: Removing static files from test

* MM-14575: Updating static files test

* MM14575: Removing cache directive from plugin static files

* MM14575: Moving plugin public directory to root

* MM-14575: Updating tests for changed public directory

* MM-14575: Moved compileGo to a common utils package for tests

* MM-14575: Moving plugins initialization to InitPlugins find in tests

* Update utils/test_files_compiler.go

Adding Copyright header

Co-Authored-By: happygaijin <happygaijin@users.noreply.github.com>

* MM-14575: Consistent usage of static vs public name

* Removing spurious newline

* Comment typo

Co-Authored-By: happygaijin <happygaijin@users.noreply.github.com>

* Removing spurious new line

Co-Authored-By: happygaijin <happygaijin@users.noreply.github.com>

* MM14575: Adding a test to make sure only public files can be requested

* MM-14575 Adding a test for redirects on public files

app/plugin_api_test.go

@@ -8,7 +8,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/mattermost/mattermost-server/utils/fileutils"
 	"image"
 	"image/color"
 	"image/png"
@@ -21,13 +20,16 @@ import (
 	"text/template"
 	"time"
 
+	"github.com/mattermost/mattermost-server/utils/fileutils"
+
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/plugin"
+	"github.com/mattermost/mattermost-server/utils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string, pluginId string, app *App) {
+func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string, pluginId string, app *App) string {
 	pluginDir, err := ioutil.TempDir("", "")
 	require.NoError(t, err)
 	webappPluginDir, err := ioutil.TempDir("", "")
@@ -39,7 +41,7 @@ func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string,
 	require.NoError(t, err)
 
 	backend := filepath.Join(pluginDir, pluginId, "backend.exe")
-	compileGo(t, pluginCode, backend)
+	utils.CompileGo(t, pluginCode, backend)
 
 	ioutil.WriteFile(filepath.Join(pluginDir, pluginId, "plugin.json"), []byte(pluginManifest), 0600)
 	manifest, activated, reterr := env.Activate(pluginId)
@@ -48,8 +50,39 @@ func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string,
 	require.True(t, activated)
 
 	app.SetPluginsEnvironment(env)
+
+	return pluginDir
 }
 
+func TestPublicFilesPathConfiguration(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	pluginID := "com.mattermost.sample"
+
+	pluginDir := setupPluginApiTest(t,
+		`
+		package main
+
+		import (
+			"github.com/mattermost/mattermost-server/plugin"
+		)
+
+		type MyPlugin struct {
+			plugin.MattermostPlugin
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+	`,
+		`{"id": "com.mattermost.sample", "server": {"executable": "backend.exe"}, "settings_schema": {"settings": []}}`, pluginID, th.App)
+
+	publicFilesFolderInTest := filepath.Join(pluginDir, pluginID, "public")
+	publicFilesPath, err := th.App.GetPluginsEnvironment().PublicFilesPath(pluginID)
+	assert.NoError(t, err)
+	assert.Equal(t, publicFilesPath, publicFilesFolderInTest)
+}
 func TestPluginAPIGetUsers(t *testing.T) {
 	th := Setup(t)
 	defer th.TearDown()
@@ -460,7 +493,7 @@ func TestPluginAPIGetPlugins(t *testing.T) {
 	var pluginManifests []*model.Manifest
 	for _, pluginID := range pluginIDs {
 		backend := filepath.Join(pluginDir, pluginID, "backend.exe")
-		compileGo(t, pluginCode, backend)
+		utils.CompileGo(t, pluginCode, backend)
 
 		ioutil.WriteFile(filepath.Join(pluginDir, pluginID, "plugin.json"), []byte(fmt.Sprintf(`{"id": "%s", "server": {"executable": "backend.exe"}}`, pluginID)), 0600)
 		manifest, activated, reterr := env.Activate(pluginID)