Have saveEnv always override an existing environment

`saveEnv` had a flag which would prevent an environment from being
overwritten if it already existed, which was only used by `lumi env
init`. Refactor the code so the check is done inside `lumi` instead of
against this API. We don't need this functionality for the service and
so requiring support for this at the API boundary for environments
feels like a bad idea.

cmd/lumi/env_init.go

@@ -4,6 +4,11 @@ package main
 
 import (
 	"errors"
+	"fmt"
+	"os"
+
+	"github.com/pulumi/pulumi-fabric/pkg/tokens"
+	"github.com/pulumi/pulumi-fabric/pkg/workspace"
 
 	"github.com/spf13/cobra"
 
@@ -25,6 +30,10 @@ func newEnvInitCmd() *cobra.Command {
 				return errors.New("missing required environment name")
 			}
 
+			if _, staterr := os.Stat(workspace.EnvPath(tokens.QName(args[0]))); staterr == nil {
+				return fmt.Errorf("environment '%v' already exists", args[0])
+			}
+
 			return lumiEngine.InitEnv(args[0])
 		}),
 	}

pkg/engine/config_delete.go

@@ -15,7 +15,7 @@ func (eng *Engine) DeleteConfig(envName string, key string) error {
 	if config != nil {
 		delete(config, tokens.Token(key))
 
-		if !eng.saveEnv(info.Target, info.Snapshot, true) {
+		if !eng.saveEnv(info.Target, info.Snapshot) {
 			return errors.Errorf("could not save configuration value")
 		}
 	}

pkg/engine/config_set.go

@@ -20,7 +20,7 @@ func (eng *Engine) SetConfig(envName string, key string, value string) error {
 
 	config[tokens.Token(key)] = value
 
-	if !eng.saveEnv(info.Target, info.Snapshot, true) {
+	if !eng.saveEnv(info.Target, info.Snapshot) {
 		return errors.Errorf("could not save configuration value")
 	}
 
@@ -43,7 +43,7 @@ func (eng *Engine) ReplaceConfig(envName string, newConfig map[string]string) er
 
 	info.Target.Config = config
 
-	if !eng.saveEnv(info.Target, info.Snapshot, true) {
+	if !eng.saveEnv(info.Target, info.Snapshot) {
 		return errors.Errorf("could not save configuration value")
 	}
 

pkg/engine/deploy.go

@@ -104,7 +104,7 @@ func (eng *Engine) deployLatest(info *envCmdInfo, opts deployOptions) error {
 			// Now save the updated snapshot Notee that if a failure has occurred, the Apply routine above will
 			// have returned a safe checkpoint.
 			targ := result.Info.Target
-			eng.saveEnv(targ, summary.Snap(), true /*overwrite*/)
+			eng.saveEnv(targ, summary.Snap())
 
 			fmt.Fprint(eng.Stdout, colors.Colorize(&footer))
 			return err

pkg/engine/env.go

@@ -61,7 +61,7 @@ type envCmdInfo struct {
 // createEnv just creates a new empty environment without deploying anything into it.
 func (eng *Engine) createEnv(name tokens.QName) {
 	env := &deploy.Target{Name: name}
-	if success := eng.saveEnv(env, nil, false); success {
+	if success := eng.saveEnv(env, nil); success {
 		fmt.Fprintf(eng.Stdout, "Environment '%v' initialized; see `lumi deploy` to deploy into it\n", name)
 		eng.setCurrentEnv(name, false)
 	}
@@ -190,7 +190,7 @@ func (eng *Engine) readEnv(name tokens.QName) (*deploy.Target, *deploy.Snapshot,
 }
 
 // saveEnv saves a new snapshot at the given location, backing up any existing ones.
-func (eng *Engine) saveEnv(env *deploy.Target, snap *deploy.Snapshot, existok bool) bool {
+func (eng *Engine) saveEnv(env *deploy.Target, snap *deploy.Snapshot) bool {
 	contract.Require(env != nil, "env")
 	file := workspace.EnvPath(env.Name)
 
@@ -210,14 +210,6 @@ func (eng *Engine) saveEnv(env *deploy.Target, snap *deploy.Snapshot, existok bo
 		return false
 	}
 
-	// If it's not ok for the file to already exist, ensure that it doesn't.
-	if !existok {
-		if _, staterr := os.Stat(file); staterr == nil {
-			glog.Errorf("An IO error occurred during the current operation: %v", goerr.Errorf("file '%v' already exists", file))
-			return false
-		}
-	}
-
 	// Back up the existing file if it already exists.
 	backupTarget(file)