Always try to select a workspace after initialization

There are a number of use cases that can require a user to select a workspace after initializing Terraform.

To make sure we cover all these use cases, we will always call the `selectWorkspace` method to verify a valid workspace is already selected or (if needed) offer to select one before moving on.

Author: Sander van Harmelen

command/init.go

@@ -210,7 +210,7 @@ func (c *InitCommand) Run(args []string) int {
 
 	if back == nil {
 		// If we didn't initialize a backend then we'll try to at least
-		// instantiate one. This might fail if it wasn't already initalized
+		// instantiate one. This might fail if it wasn't already initialized
 		// by a previous run, so we must still expect that "back" may be nil
 		// in code that follows.
 		back, err = c.Backend(nil)

command/meta_backend.go

@@ -10,6 +10,7 @@ import (
 	"io/ioutil"
 	"log"
 	"path/filepath"
+	"strconv"
 	"strings"
 
 	"github.com/hashicorp/go-multierror"
@@ -86,6 +87,11 @@ func (m *Meta) Backend(opts *BackendOpts) (backend.Enhanced, error) {
 			b, err = m.backendFromPlan(opts)
 		} else {
 			b, err = m.backendFromConfig(opts)
+			if opts.Init && b != nil && err == nil {
+				// Its possible that the currently selected workspace doesn't exist, so
+				// we call selectWorkspace to ensure an existing workspace is selected.
+				err = m.selectWorkspace(b)
+			}
 		}
 		if err != nil {
 			return nil, err
@@ -145,6 +151,56 @@ func (m *Meta) Backend(opts *BackendOpts) (backend.Enhanced, error) {
 	return local, nil
 }
 
+// selectWorkspace gets a list of existing workspaces and then checks
+// if the currently selected workspace is valid. If not, it will ask
+// the user to select a workspace from the list.
+func (m *Meta) selectWorkspace(b backend.Backend) error {
+	workspaces, err := b.States()
+	if err == backend.ErrNamedStatesNotSupported {
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("Failed to get existing workspaces: %s", err)
+	}
+	if len(workspaces) == 0 {
+		return fmt.Errorf(errBackendNoExistingWorkspaces)
+	}
+
+	// Get the currently selected workspace.
+	workspace := m.Workspace()
+
+	// Check if any of the existing workspaces matches the selected
+	// workspace and create a numbered list of existing workspaces.
+	var list strings.Builder
+	for i, w := range workspaces {
+		if w == workspace {
+			return nil
+		}
+		fmt.Fprintf(&list, "%d. %s\n", i+1, w)
+	}
+
+	// If the selected workspace doesn't exist, ask the user to select
+	// a workspace from the list of existing workspaces.
+	v, err := m.UIInput().Input(context.Background(), &terraform.InputOpts{
+		Id: "select-workspace",
+		Query: fmt.Sprintf(
+			"[reset][bold][yellow]The currently selected workspace (%s) does not exist.[reset]",
+			workspace),
+		Description: fmt.Sprintf(
+			strings.TrimSpace(inputBackendSelectWorkspace), list.String()),
+	})
+	if err != nil {
+		return fmt.Errorf("Error asking to select workspace: %s", err)
+	}
+
+	idx, err := strconv.Atoi(v)
+	if err != nil || (idx < 1 || idx > len(workspaces)) {
+		return fmt.Errorf("Error selecting workspace: input not a valid number")
+	}
+
+	return m.SetWorkspace(workspaces[idx-1])
+}
+
 // IsLocalBackend returns true if the backend is a local backend. We use this
 // for some checks that require a remote backend.
 func (m *Meta) IsLocalBackend(b backend.Backend) bool {
@@ -997,7 +1053,6 @@ func (m *Meta) backend_C_r_s(
 	m.Ui.Output(m.Colorize().Color(fmt.Sprintf(
 		"[reset][green]\n"+strings.TrimSpace(successBackendSet), s.Backend.Type)))
 
-	// Return the backend
 	return b, nil
 }
 
@@ -1408,6 +1463,14 @@ If you'd like to run Terraform and store state locally, you can fix this
 error by removing the backend configuration from your configuration.
 `
 
+const errBackendNoExistingWorkspaces = `
+No existing workspaces. Use the "terraform workspace" command to create
+and select a new workspace.
+
+If the backend already contains existing workspaces, you may need to update
+the workspace name or prefix in the backend configuration.
+`
+
 const errBackendRemoteRead = `
 Error reading backend state: %s
 

command/meta_backend_migrate.go

@@ -8,7 +8,6 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
-	"strconv"
 	"strings"
 
 	"github.com/hashicorp/terraform/backend"
@@ -169,56 +168,7 @@ func (m *Meta) backendMigrateState_S_S(opts *backendMigrateOpts) error {
 		}
 	}
 
-	// Its possible that the currently selected workspace is not migrated,
-	// so we call selectWorkspace to ensure a valid workspace is selected.
-	return m.selectWorkspace(opts.Two)
-}
-
-// selectWorkspace gets a list of migrated workspaces and then checks
-// if the currently selected workspace is valid. If not, it will ask
-// the user to select a workspace from the list.
-func (m *Meta) selectWorkspace(b backend.Backend) error {
-	workspaces, err := b.States()
-	if err != nil {
-		return fmt.Errorf("Failed to get migrated workspaces: %s", err)
-	}
-	if len(workspaces) == 0 {
-		return fmt.Errorf(errBackendNoMigratedWorkspaces)
-	}
-
-	// Get the currently selected workspace.
-	workspace := m.Workspace()
-
-	// Check if any of the migrated workspaces match the selected workspace
-	// and create a numbered list with migrated workspaces.
-	var list strings.Builder
-	for i, w := range workspaces {
-		if w == workspace {
-			return nil
-		}
-		fmt.Fprintf(&list, "%d. %s\n", i+1, w)
-	}
-
-	// If the selected workspace is not migrated, ask the user to select
-	// a workspace from the list of migrated workspaces.
-	v, err := m.UIInput().Input(context.Background(), &terraform.InputOpts{
-		Id: "select-workspace",
-		Query: fmt.Sprintf(
-			"[reset][bold][yellow]The currently selected workspace (%s) is not migrated.[reset]",
-			workspace),
-		Description: fmt.Sprintf(
-			strings.TrimSpace(inputBackendSelectWorkspace), list.String()),
-	})
-	if err != nil {
-		return fmt.Errorf("Error asking to select workspace: %s", err)
-	}
-
-	idx, err := strconv.Atoi(v)
-	if err != nil || (idx < 1 || idx > len(workspaces)) {
-		return fmt.Errorf("Error selecting workspace: input not a valid number")
-	}
-
-	return m.SetWorkspace(workspaces[idx-1])
+	return nil
 }
 
 // Multi-state to single state.
@@ -530,14 +480,6 @@ The state in the previous backend remains intact and unmodified. Please resolve
 the error above and try again.
 `
 
-const errBackendNoMigratedWorkspaces = `
-No workspaces are migrated. Use the "terraform workspace" command to create
-and select a new workspace.
-
-If the backend already contains existing workspaces, you may need to update
-the workspace name or prefix in the backend configuration.
-`
-
 const inputBackendMigrateEmpty = `
 Pre-existing state was found while migrating the previous %q backend to the
 newly configured %q backend. No existing state was found in the newly