command/push: Allow existing state file to enable remote

command/push.go

@@ -1,8 +1,12 @@
 package command
 
 import (
+	"bytes"
 	"flag"
 	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
 	"strings"
 
 	"github.com/hashicorp/terraform/remote"
@@ -15,9 +19,12 @@ type PushCommand struct {
 
 func (c *PushCommand) Run(args []string) int {
 	var force bool
+	var statePath, backupPath string
 	var remoteConf terraform.RemoteState
 	args = c.Meta.process(args, false)
 	cmdFlags := flag.NewFlagSet("push", flag.ContinueOnError)
+	cmdFlags.StringVar(&statePath, "state", "", "path")
+	cmdFlags.StringVar(&backupPath, "backup", "", "path")
 	cmdFlags.StringVar(&remoteConf.Name, "remote", "", "")
 	cmdFlags.StringVar(&remoteConf.Server, "remote-server", "", "")
 	cmdFlags.StringVar(&remoteConf.AuthToken, "remote-auth", "", "")
@@ -27,30 +34,129 @@ func (c *PushCommand) Run(args []string) int {
 		return 1
 	}
 
-	// Validate the remote configuration if given
-	var conf *terraform.RemoteState
-	if !remoteConf.Empty() {
-		if err := remote.ValidateConfig(&remoteConf); err != nil {
+	// Check for a remote state file
+	local, _, err := remote.ReadLocalState()
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("%s", err))
+		return 1
+	}
+
+	// Check for the default state file if not specified
+	if statePath == "" {
+		statePath = DefaultStateFilename
+	}
+
+	// Check if an alternative state file exists
+	raw, err := ioutil.ReadFile(statePath)
+	if err != nil {
+		// Ignore if the state path does not exist if it is the default
+		// state file path, since that means the user didn't provide any
+		// input.
+		if !(os.IsNotExist(err) && statePath == DefaultStateFilename) {
+			c.Ui.Error(fmt.Sprintf("Failed to open state file at '%s': %v",
+				statePath, err))
+			return 1
+		}
+	}
+
+	// Check if both state files are provided!
+	if local != nil && raw != nil {
+		c.Ui.Error(fmt.Sprintf(`Remote state enabled and default state file is also present.
+Please rename the state file at '%s' to prevent a conflict.`, statePath))
+		return 1
+	}
+
+	// Check if there is no state to push!
+	if local == nil && raw == nil {
+		c.Ui.Error("No state to push")
+		return 1
+	}
+
+	// Handle the initial enabling of remote state
+	if local == nil && raw != nil {
+		if err := c.enableRemote(&remoteConf, raw, statePath, backupPath); err != nil {
 			c.Ui.Error(fmt.Sprintf("%s", err))
 			return 1
 		}
-		conf = &remoteConf
-	} else {
-		// Recover the local state if any
-		local, _, err := remote.ReadLocalState()
+	}
+
+	return c.doPush(force)
+}
+
+// enableRemote is used when we get a state file that is not remote enabled,
+// and need to move it into the hidden directory and enable remote storage.
+func (c *PushCommand) enableRemote(conf *terraform.RemoteState, rawState []byte,
+	statePath, backupPath string) error {
+	// If there is no local file, ensure we have the remote
+	// state is properly configured
+	if conf.Empty() {
+		return fmt.Errorf("Missing remote configuration")
+	}
+	if err := remote.ValidateConfig(conf); err != nil {
+		return err
+	}
+
+	// Decode the state
+	state, err := terraform.ReadState(bytes.NewReader(rawState))
+	if err != nil {
+		return fmt.Errorf("Failed to decode state file at '%s': %v",
+			statePath, err)
+	}
+
+	// Backup the state file before we remove it
+	if backupPath != "-" {
+		// If we don't specify a backup path, default to state out with
+		// the extension
+		if backupPath == "" {
+			backupPath = statePath + DefaultBackupExtention
+		}
+
+		log.Printf("[INFO] Writing backup state to: %s", backupPath)
+		f, err := os.Create(backupPath)
+		if err == nil {
+			err = terraform.WriteState(state, f)
+			f.Close()
+		}
 		if err != nil {
-			c.Ui.Error(fmt.Sprintf("%s", err))
-			return 1
+			return fmt.Errorf("Error writing backup state file: %s", err)
 		}
-		if local == nil || local.Remote == nil {
-			c.Ui.Error("No remote state server configured")
-			return 1
-		}
-		conf = local.Remote
+	}
+
+	// Get the target path for the remote state file
+	path, err := remote.HiddenStatePath()
+	if err != nil {
+		return nil
+	}
+
+	// Install the state file in the hidden directory
+	state.Remote = conf
+	f, err := os.Create(path)
+	if err == nil {
+		err = terraform.WriteState(state, f)
+		f.Close()
+	}
+	if err != nil {
+		return fmt.Errorf("Error copying state file: %s", err)
+	}
+
+	// Remove the old state file
+	if err := os.Remove(statePath); err != nil {
+		return fmt.Errorf("Error removing state file: %s", err)
+	}
+	return nil
+}
+
+// doPush is used to attempt the state push
+func (c *PushCommand) doPush(force bool) int {
+	// Recover the local state if any
+	local, _, err := remote.ReadLocalState()
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("%s", err))
+		return 1
 	}
 
 	// Attempt to push the state
-	change, err := remote.PushState(conf, force)
+	change, err := remote.PushState(local.Remote, force)
 	if err != nil {
 		c.Ui.Error(fmt.Sprintf(
 			"Failed to push state: %v", err))
@@ -71,12 +177,16 @@ func (c *PushCommand) Help() string {
 	helpText := `
 Usage: terraform push [options]
 
-  Uploads the local state file to the remote server. This is done automatically
-  by commands when remote state if configured, but can also be done manually
-  using this command.
+  Uploads the latest state to the remote server. This command can
+  also be used to push an existing state file into a remote server and
+  to enable automatic state management.
 
 Options:
 
+  -backup=path           Path to backup the existing state file before
+                         modifying. Defaults to the "-state" path with
+                         ".backup" extension. Set to "-" to disable backup.
+
   -force                 Forces the upload of the local state, ignoring any
                          conflicts. This should be used carefully, as force pushing
 						 can cause remote state information to be lost.
@@ -89,6 +199,9 @@ Options:
 
   -remote-server=url     URL of the remote storage server.
 
+  -state=path            Path to read state. Defaults to "terraform.tfstate"
+                         unless remote state is enabled.
+
 `
 	return strings.TrimSpace(helpText)
 }

command/push_test.go

@@ -2,6 +2,8 @@ package command
 
 import (
 	"bytes"
+	"io/ioutil"
+	"os"
 	"testing"
 
 	"github.com/hashicorp/terraform/remote"
@@ -50,6 +52,50 @@ func TestPush_cliRemote_noState(t *testing.T) {
 	}
 }
 
+func TestPush_cliRemote_withState(t *testing.T) {
+	tmp, cwd := testCwd(t)
+	defer fixDir(tmp, cwd)
+
+	s := terraform.NewState()
+	conf, srv := testRemoteState(t, s, 200)
+	defer srv.Close()
+
+	s = terraform.NewState()
+	s.Serial = 10
+
+	// Store the local state
+	buf := bytes.NewBuffer(nil)
+	terraform.WriteState(s, buf)
+	err := ioutil.WriteFile(DefaultStateFilename, buf.Bytes(), 0777)
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+
+	ui := new(cli.MockUi)
+	c := &PushCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	// Remote with default state file
+	args := []string{"-remote", conf.Name, "-remote-server", conf.Server}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	// Should backup state
+	if _, err := os.Stat(DefaultStateFilename + DefaultBackupExtention); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Should enable remote state
+	if _, err := os.Stat(remote.LocalDirectory + "/" + remote.HiddenStateFile); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+}
+
 func TestPush_local(t *testing.T) {
 	tmp, cwd := testCwd(t)
 	defer fixDir(tmp, cwd)
@@ -57,11 +103,11 @@ func TestPush_local(t *testing.T) {
 	s := terraform.NewState()
 	s.Serial = 5
 	conf, srv := testRemoteState(t, s, 200)
+	defer srv.Close()
 
 	s = terraform.NewState()
 	s.Serial = 10
 	s.Remote = conf
-	defer srv.Close()
 
 	// Store the local state
 	buf := bytes.NewBuffer(nil)