Add optional delete flag for destination key deletion

cli.go

@@ -381,6 +381,11 @@ func (cli *CLI) ParseFlags(args []string) (*Config, []string, bool, bool, error)
 		return nil
 	}), "wait", "")
 
+	flags.Var((funcBoolVar)(func(b bool) error {
+		c.DeleteKey = config.Bool(b)
+		return nil
+	}), "delete", "")
+
 	flags.BoolVar(&isVersion, "v", false, "")
 	flags.BoolVar(&isVersion, "version", false, "")
 
@@ -618,6 +623,10 @@ Options:
       Sets the 'min(:max)' amount of time to wait before writing a template (and
       triggering a command)
 
+  -delete=<boolean>
+      Enables deletion of keys in the destination datacenter that do not exist
+      in the source datacenter. Defaults to true
+
   -v, -version
       Print the version of this daemon
 `

config.go

@@ -35,6 +35,8 @@ const (
 
 	// DefaultStatusDir is the default directory to post status information.
 	DefaultStatusDir = "service/consul-replicate/statuses"
+	// DefaultDeleteKey is the default value for deleting destination keys if source keys are empty.
+	DefaultDeleteKey = true
 )
 
 // Config is used to configure Consul ENV
@@ -74,6 +76,8 @@ type Config struct {
 
 	// Wait is the quiescence timers.
 	Wait *config.WaitConfig `mapstructure:"wait"`
+
+	DeleteKey *bool `mapstructure:"delete_key"`
 }
 
 // Copy returns a deep copy of the current configuration. This is useful because
@@ -113,6 +117,8 @@ func (c *Config) Copy() *Config {
 		o.Wait = c.Wait.Copy()
 	}
 
+	o.DeleteKey = c.DeleteKey
+
 	return &o
 }
 
@@ -174,6 +180,10 @@ func (c *Config) Merge(o *Config) *Config {
 		r.Wait = r.Wait.Merge(o.Wait)
 	}
 
+	if o.DeleteKey != nil {
+		r.DeleteKey = o.DeleteKey
+	}
+
 	return r
 }
 
@@ -195,6 +205,7 @@ func (c *Config) GoString() string {
 		"StatusDir:%s, "+
 		"Syslog:%s, "+
 		"Wait:%s"+
+		"DeleteKey:%s"+
 		"}",
 		c.Consul.GoString(),
 		c.Excludes.GoString(),
@@ -207,19 +218,22 @@ func (c *Config) GoString() string {
 		config.StringGoString(c.StatusDir),
 		c.Syslog.GoString(),
 		c.Wait.GoString(),
+		config.BoolGoString(c.DeleteKey),
 	)
 }
 
 // DefaultConfig returns the default configuration struct. Certain environment
 // variables may be set which control the values for the default configuration.
 func DefaultConfig() *Config {
+
 	return &Config{
 		Consul:    config.DefaultConsulConfig(),
 		Excludes:  DefaultExcludeConfigs(),
 		Prefixes:  DefaultPrefixConfigs(),
 		StatusDir: config.String(DefaultStatusDir),
 		Syslog:    config.DefaultSyslogConfig(),
 		Wait:      config.DefaultWaitConfig(),
+		DeleteKey: config.Bool(DefaultDeleteKey),
 	}
 }
 
@@ -284,6 +298,10 @@ func (c *Config) Finalize() {
 		c.Wait = config.DefaultWaitConfig()
 	}
 	c.Wait.Finalize()
+
+	if c.DeleteKey == nil {
+		c.DeleteKey = config.Bool(DefaultDeleteKey)
+	}
 }
 
 // Parse parses the given string contents as a config

runner.go

@@ -201,7 +201,7 @@ func (r *Runner) Run() error {
 
 	// Replicate each prefix in a goroutine
 	for _, prefix := range prefixes {
-		go r.replicate(prefix, r.config.Excludes, doneCh, errCh)
+		go r.replicate(prefix, r.config.Excludes, r.config.DeleteKey, doneCh, errCh)
 	}
 
 	var errs *multierror.Error
@@ -268,7 +268,7 @@ func (r *Runner) get(prefix *PrefixConfig) (*watch.View, bool) {
 // replicate performs replication into the current datacenter from the given
 // prefix. This function is designed to be called via a goroutine since it is
 // expensive and needs to be parallelized.
-func (r *Runner) replicate(prefix *PrefixConfig, excludes *ExcludeConfigs, doneCh chan struct{}, errCh chan error) {
+func (r *Runner) replicate(prefix *PrefixConfig, excludes *ExcludeConfigs, deleteKey *bool, doneCh chan struct{}, errCh chan error) {
 	// Ensure we are not self-replicating
 	info, err := r.clients.Consul().Agent().Self()
 	if err != nil {
@@ -376,7 +376,6 @@ func (r *Runner) replicate(prefix *PrefixConfig, excludes *ExcludeConfigs, doneC
 	}
 	for _, key := range localKeys {
 		excluded := false
-
 		// Ignore if the key falls under an excluded prefix
 		if len(*excludes) > 0 {
 			sourceKey := strings.Replace(key, config.StringVal(prefix.Destination), config.StringVal(prefix.Source), -1)
@@ -389,13 +388,15 @@ func (r *Runner) replicate(prefix *PrefixConfig, excludes *ExcludeConfigs, doneC
 			}
 		}
 
-		if _, ok := usedKeys[key]; !ok && !excluded {
+		if _, ok := usedKeys[key]; !ok && !excluded && *deleteKey {
 			if _, err := kv.Delete(key, nil); err != nil {
 				errCh <- fmt.Errorf("failed to delete %q: %s", key, err)
 				return
 			}
 			log.Printf("[DEBUG] (runner) deleted %q", key)
 			deletes++
+		} else if _, ok := usedKeys[key]; !ok && !excluded && !*deleteKey {
+			log.Printf("DEBUG (runner) %q key exists in destination and not source", key)
 		}
 	}