Remove virtualenv install fallback

Previously trellis-cli tried to fallback to installing virtualenv if no
other method was found. Turns out this was completely broken!

Since it's a complicated feature to offer, and users should really
install it manually themselves, this feature is being removed entirely
for now.

This also improves the existing `python3 -m venv` detection feature by
adding an additional check to make sure it actually exists. This catches
an edge case for Ubuntu/Debian/WSL users because their python3 package
does not include venv.

Now those users will be shown an error letting them know what needs to
be done.

Author: swalkinshaw

cmd/init.go

@@ -56,31 +56,15 @@ func (c *InitCommand) Run(args []string) int {
 		return 1
 	}
 
-	c.UI.Info("Initializing project\n")
+	c.UI.Info("Initializing project...\n")
 	ok, virtualenvCmd := c.Trellis.Virtualenv.Installed()
 
 	if !ok {
-		c.UI.Info("virtualenv not found")
-		spinner := NewSpinner(
-			SpinnerCfg{
-				Message:     "Installing virtualenv",
-				FailMessage: "Error installing virtualenv",
-			},
-		)
-		spinner.Start()
-		_, err := c.Trellis.Virtualenv.Install()
-		spinner.Stop()
-
-		c.UI.Error(err.Error())
-		c.UI.Error("")
-		c.UI.Error("Project initialization failed due to the error above.")
+		c.UI.Error("virtualenv not found. trellis-cli looked for two options:")
+		c.UI.Error("  1. python3's built-in `venv` module")
+		c.UI.Error("  2. standalone `virtualenv` command")
 		c.UI.Error("")
-		c.UI.Error("trellis-cli attempted to install virtualenv as a fallback but failed.")
-		c.UI.Error("Without virtualenv, a Python virtual environment cannot be created and the required dependencies (eg: Ansible) can't be installed either.")
-		c.UI.Error("")
-		c.UI.Error("There are two options:")
-		c.UI.Error("  1. Ensure Python 3 is installed and the `python3` command works. trellis-cli will use python3's built-in venv feature.")
-		c.UI.Error(fmt.Sprintf("  2. Disable trellis-cli's virtual env feature by setting this env variable: export %s=false", trellis.TrellisVenvEnvName))
+		virtualenvError(c.UI)
 		return 1
 	}
 
@@ -123,13 +107,7 @@ func (c *InitCommand) Run(args []string) int {
 			c.UI.Error("trellis-cli tried to create a virtual environment but failed.")
 			c.UI.Error(fmt.Sprintf("  => %s", virtualenvCmd.String()))
 			c.UI.Error("")
-			c.UI.Error("Without a Python virtual environment the required dependencies (eg: Ansible) can't be installed.")
-			c.UI.Error("")
-			c.UI.Error("There are two options:")
-			c.UI.Error("  1. Ensure Python 3 is installed and the `python3` command works. trellis-cli will use python3's built-in venv feature.")
-			c.UI.Error(fmt.Sprintf("  2. Disable trellis-cli's virtual env feature by setting this env variable: export %s=false", trellis.TrellisVenvEnvName))
-			c.UI.Error("")
-			c.UI.Error("This could also be a bug in trellis-cli. Please create an issue at https://github.com/roots/trellis-cli and include the output above.")
+			virtualenvError(c.UI)
 			return 1
 		}
 
@@ -199,3 +177,14 @@ Options:
 
 	return strings.TrimSpace(helpText)
 }
+
+func virtualenvError(ui cli.Ui) {
+	ui.Error("Without virtualenv, a Python virtual environment cannot be created and the required dependencies (eg: Ansible) can't be installed either.")
+	ui.Error("")
+	ui.Error("There are two options:")
+	ui.Error("  1. Ensure Python 3 is installed and the `python3` command works. trellis-cli will use python3's built-in venv feature.")
+	ui.Error("     Ubuntu/Debian users (including Windows WSL): venv is not built-in, to install it run `sudo apt-get install python3-pip python3-venv`")
+	ui.Error("")
+	ui.Error("  2. Disable trellis-cli's virtual env feature, and manage dependencies manually, by setting this env variable:")
+	ui.Error(fmt.Sprintf("     export %s=false", trellis.TrellisVenvEnvName))
+}

trellis/virtualenv.go

@@ -2,12 +2,11 @@ package trellis
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
 
-	"github.com/roots/trellis-cli/github"
+	"github.com/roots/trellis-cli/command"
 )
 
 const TrellisVenvEnvName string = "TRELLIS_VENV"
@@ -73,21 +72,6 @@ func (v *Virtualenv) Delete() error {
 	return os.RemoveAll(v.Path)
 }
 
-func (v *Virtualenv) LocalPath() string {
-	configHome := os.Getenv("XDG_CONFIG_HOME")
-
-	if configHome == "" {
-		homeDir, err := os.UserHomeDir()
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		configHome = filepath.Join(homeDir, ".local", "share")
-	}
-
-	return filepath.Join(configHome, "trellis", "virtualenv")
-}
-
 func (v *Virtualenv) Initialized() bool {
 	if _, err := os.Stat(filepath.Join(v.BinPath, "python")); os.IsNotExist(err) {
 		return false
@@ -100,34 +84,19 @@ func (v *Virtualenv) Initialized() bool {
 	return true
 }
 
-func (v *Virtualenv) Install() (installPath string, err error) {
-	localPath := v.LocalPath()
-	configDir := filepath.Dir(localPath)
-
-	if _, err = os.Stat(configDir); os.IsNotExist(err) {
-		if err = os.MkdirAll(configDir, 0755); err != nil {
-			return "", err
-		}
-	}
-
-	return github.DownloadRelease("pypa/virtualenv", "latest", os.TempDir(), localPath), nil
-}
-
 func (v *Virtualenv) Installed() (ok bool, cmd *exec.Cmd) {
 	path, err := exec.LookPath("python3")
 	if err == nil {
-		return true, exec.Command(path, "-m", "venv")
+		err = command.Cmd(path, []string{"-m", "ensurepip", "--version"}).Run()
+
+		if err == nil {
+			return true, command.Cmd(path, []string{"-m", "venv"})
+		}
 	}
 
 	path, err = exec.LookPath("virtualenv")
 	if err == nil {
-		return true, exec.Command(path)
-	}
-
-	localVenvPath := filepath.Join(v.LocalPath(), "virtualenv.py")
-
-	if _, err = os.Stat(localVenvPath); !os.IsNotExist(err) {
-		return true, exec.Command("python", localVenvPath)
+		return true, command.Cmd(path, []string{})
 	}
 
 	return false, nil

trellis/virtualenv_test.go

@@ -1,12 +1,16 @@
 package trellis
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"github.com/roots/trellis-cli/command"
 )
 
 func TestNewVirtualenv(t *testing.T) {
@@ -103,30 +107,6 @@ func TestDeactive(t *testing.T) {
 	}
 }
 
-func TestLocalPath(t *testing.T) {
-	venv := NewVirtualenv("trellis")
-	originalConfigHome := os.Getenv("XDG_CONFIG_HOME")
-	os.Unsetenv("XDG_CONFIG_HOME")
-	defer os.Setenv("XDG_CONFIG_HOME", originalConfigHome)
-
-	homeDir, _ := os.UserHomeDir()
-
-	localPath := venv.LocalPath()
-
-	if localPath != filepath.Join(homeDir, ".local/share/trellis/virtualenv") {
-		t.Error("Expected LocalPath to default to $USER/.local/share")
-	}
-
-	os.Setenv("XDG_CONFIG_HOME", "mydir")
-	defer os.Setenv("XDG_CONFIG_HOME", originalConfigHome)
-
-	localPath = venv.LocalPath()
-
-	if localPath != filepath.Join("mydir", "trellis/virtualenv") {
-		t.Error("Expected LocalPath to use XDG_CONFIG_HOME when set")
-	}
-}
-
 func TestInitialized(t *testing.T) {
 	tempDir, err := ioutil.TempDir("", "trellis")
 	defer os.RemoveAll(tempDir)
@@ -163,7 +143,7 @@ func TestInstalled(t *testing.T) {
 	}
 }
 
-func TestInstalledPython3(t *testing.T) {
+func TestInstalledPython3WithEnsurepip(t *testing.T) {
 	tempDir, err := ioutil.TempDir("", "trellis")
 	defer os.RemoveAll(tempDir)
 
@@ -178,18 +158,36 @@ func TestInstalledPython3(t *testing.T) {
 
 	venv := NewVirtualenv(tempDir)
 
+	var output bytes.Buffer
+
+	mockExecCommand := func(command string, args []string) *exec.Cmd {
+		cs := []string{"-test.run=TestEnsurePipSuccessHelperProcess", "--", command}
+		cs = append(cs, args...)
+		cmd := exec.Command(os.Args[0], cs...)
+		cmd.Stderr = &output
+		cmd.Stdout = &output
+		cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
+		return cmd
+	}
+
+	command.Mock(mockExecCommand)
+	defer command.Restore()
+
 	ok, cmd := venv.Installed()
 
 	if !ok {
 		t.Error("Expected to be installed")
 	}
 
-	if strings.Join(cmd.Args, " ") != fmt.Sprintf("%s -m venv", pythonPath) {
-		t.Error("Expected args incorrect")
+	expected := "python3 -m venv"
+	actual := cmd.String()
+
+	if !strings.Contains(actual, expected) {
+		t.Errorf("Expected command incorrect.\nexpected: %s\ngot: %s", expected, actual)
 	}
 }
 
-func TestInstalledVirtualenv(t *testing.T) {
+func TestInstalledPython3WithoutEnsurepip(t *testing.T) {
 	tempDir, err := ioutil.TempDir("", "trellis")
 	defer os.RemoveAll(tempDir)
 
@@ -199,45 +197,55 @@ func TestInstalledVirtualenv(t *testing.T) {
 
 	defer testSetEnv("PATH", tempDir)()
 
-	venvPath := filepath.Join(tempDir, "virtualenv")
-	os.OpenFile(venvPath, os.O_CREATE, 0555)
-
-	venv := NewVirtualenv(tempDir)
+	pythonPath := filepath.Join(tempDir, "python3")
+	os.OpenFile(pythonPath, os.O_CREATE, 0555)
 
-	ok, cmd := venv.Installed()
+	var output bytes.Buffer
 
-	if !ok {
-		t.Error("Expected to be installed")
+	mockExecCommand := func(command string, args []string) *exec.Cmd {
+		cs := []string{"-test.run=TestEnsurePipFailureHelperProcess", "--", command}
+		cs = append(cs, args...)
+		cmd := exec.Command(os.Args[0], cs...)
+		cmd.Stderr = &output
+		cmd.Stdout = &output
+		cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
+		return cmd
 	}
 
-	if strings.Join(cmd.Args, " ") != venvPath {
-		t.Error("Expected args incorrect")
+	command.Mock(mockExecCommand)
+	defer command.Restore()
+
+	venv := NewVirtualenv(tempDir)
+
+	ok, _ := venv.Installed()
+
+	if ok {
+		t.Error("Expected not to be installed")
 	}
 }
 
-func TestInstalledLocalVirtualenv(t *testing.T) {
+func TestInstalledVirtualenv(t *testing.T) {
 	tempDir, err := ioutil.TempDir("", "trellis")
 	defer os.RemoveAll(tempDir)
 
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
 
-	defer testSetEnv("PATH", "")()
-	defer testSetEnv("XDG_CONFIG_HOME", tempDir)()
+	defer testSetEnv("PATH", tempDir)()
+
+	venvPath := filepath.Join(tempDir, "virtualenv")
+	os.OpenFile(venvPath, os.O_CREATE, 0555)
 
 	venv := NewVirtualenv(tempDir)
-	localVenvPath := filepath.Join(venv.LocalPath(), "virtualenv.py")
-	os.MkdirAll(venv.LocalPath(), os.ModePerm)
-	testCreateFile(t, localVenvPath)()
 
 	ok, cmd := venv.Installed()
 
 	if !ok {
 		t.Error("Expected to be installed")
 	}
 
-	if strings.Join(cmd.Args, " ") != fmt.Sprintf("python %s", localVenvPath) {
+	if strings.Join(cmd.Args, " ") != venvPath {
 		t.Error("Expected args incorrect")
 	}
 }
@@ -257,3 +265,21 @@ func testSetEnv(env string, value string) func() {
 	os.Setenv(env, value)
 	return func() { os.Setenv(env, old) }
 }
+
+func TestEnsurePipSuccessHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	fmt.Fprintf(os.Stdout, strings.Join(os.Args[3:], " "))
+	os.Exit(0)
+}
+
+func TestEnsurePipFailureHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	fmt.Fprintf(os.Stderr, strings.Join(os.Args[3:], " "))
+	os.Exit(1)
+}