Add it as a command line option

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

nats-streaming-server.go

@@ -52,6 +52,7 @@ Streaming Server Options:
           --encrypt <bool>               Specify if server should use encryption at rest
           --encryption_cipher <string>   Cipher to use for encryption. Currently support AES and CHAHA (ChaChaPoly). Defaults to AES
           --encryption_key <string>      Encryption Key. It is recommended to specify it through the NATS_STREAMING_ENCRYPTION_KEY environment variable instead
+          --replace_durable <bool>       Replace the existing durable subscription instead of reporting a duplicate durable error
 
 Streaming Server Clustering Options:
     --clustered <bool>                     Run the server in a clustered configuration (default: false)

server/conf.go

@@ -692,6 +692,7 @@ func ConfigureOptions(fs *flag.FlagSet, args []string, printVersion, printHelp,
 	fs.BoolVar(&sopts.Encrypt, "encrypt", false, "Specify if server should use encryption at rest")
 	fs.StringVar(&sopts.EncryptionCipher, "encryption_cipher", stores.CryptoCipherAutoSelect, "Encryption cipher. Supported are AES and CHACHA (default is AES)")
 	fs.StringVar(&encryptionKey, "encryption_key", "", "Encryption Key. It is recommended to specify it through the NATS_STREAMING_ENCRYPTION_KEY environment variable instead")
+	fs.BoolVar(&sopts.ReplaceDurable, "replace_durable", false, "Replace the existing durable subscription instead of reporting a duplicate durable error")
 
 	// First, we need to call NATS's ConfigureOptions() with above flag set.
 	// It will be augmented with NATS specific flags and call fs.Parse(args) for us.