loopd: recorgnize maxlsatcost and maxlsatfee flags

The flags were re-added in hidden mode so that users who specified them
could start the daemon after upgrading. If a flag is used, a deprecation
warning is printed.

Updated release_notes.md.

loopd/config.go

@@ -160,6 +160,8 @@ type Config struct {
 	MaxLogFileSize int    `long:"maxlogfilesize" description:"Maximum logfile size in MB."`
 
 	DebugLevel  string `long:"debuglevel" description:"Logging level for all subsystems {trace, debug, info, warn, error, critical} -- You may also specify <subsystem>=<level>,<subsystem2>=<level>,... to set the log level for individual subsystems -- Use show to list available subsystems"`
+	MaxLSATCost uint32 `long:"maxlsatcost" hidden:"true"`
+	MaxLSATFee  uint32 `long:"maxlsatfee" hidden:"true"`
 	MaxL402Cost uint32 `long:"maxl402cost" description:"Maximum cost in satoshis that loopd is going to pay for an L402 token automatically. Does not include routing fees."`
 	MaxL402Fee  uint32 `long:"maxl402fee" description:"Maximum routing fee in satoshis that we are willing to pay while paying for an L402 token."`
 

loopd/utils.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/lightninglabs/aperture/l402"
 	"github.com/lightninglabs/lndclient"
 	"github.com/lightninglabs/loop"
 	"github.com/lightninglabs/loop/liquidity"
@@ -21,6 +22,23 @@ func getClient(cfg *Config, swapDb loopdb.SwapStore,
 	sweeperDb sweepbatcher.BatcherStore, lnd *lndclient.LndServices) (
 	*loop.Client, func(), error) {
 
+	// Default is not set for MaxLSATCost and MaxLSATFee to distinguish
+	// it from user explicitly setting the option to default value.
+	// So if MaxL402Cost and MaxLSATFee are not set in the config file
+	// and command line, they are set to 0.
+	const (
+		defaultCost = l402.DefaultMaxCostSats
+		defaultFee  = l402.DefaultMaxRoutingFeeSats
+	)
+	if cfg.MaxL402Cost != defaultCost && cfg.MaxLSATCost != 0 {
+		return nil, nil, fmt.Errorf("both maxl402cost and maxlsatcost" +
+			" were specified; they are not allowed together")
+	}
+	if cfg.MaxL402Fee != defaultFee && cfg.MaxLSATFee != 0 {
+		return nil, nil, fmt.Errorf("both maxl402fee and maxlsatfee" +
+			" were specified; they are not allowed together")
+	}
+
 	clientConfig := &loop.ClientConfig{
 		ServerAddress:       cfg.Server.Host,
 		ProxyAddress:        cfg.Server.Proxy,
@@ -34,6 +52,17 @@ func getClient(cfg *Config, swapDb loopdb.SwapStore,
 		MaxPaymentRetries:   cfg.MaxPaymentRetries,
 	}
 
+	if cfg.MaxL402Cost == defaultCost && cfg.MaxLSATCost != 0 {
+		log.Warnf("Option maxlsatcost is deprecated and will be " +
+			"removed. Switch to maxl402cost.")
+		clientConfig.MaxL402Cost = btcutil.Amount(cfg.MaxLSATCost)
+	}
+	if cfg.MaxL402Fee == defaultFee && cfg.MaxLSATFee != 0 {
+		log.Warnf("Option maxlsatfee is deprecated and will be " +
+			"removed. Switch to maxl402fee.")
+		clientConfig.MaxL402Fee = btcutil.Amount(cfg.MaxLSATFee)
+	}
+
 	swapClient, cleanUp, err := loop.NewClient(
 		cfg.DataDir, swapDb, sweeperDb, clientConfig,
 	)

release_notes.md

@@ -19,8 +19,9 @@ This file tracks release notes for the loop client.
 #### Breaking Changes
 
 In loopd.conf file `maxlsatcost` and `maxlsatfee` were renamed to `maxl402cost`
-and `maxl402fee` accordingly. If they have been changed locally, the file has
-to be updated for loopd to recognize the options.
+and `maxl402fee` accordingly. Old versions of the options are still recognized
+for backward compatibility, but a deprecation warning is printed. Users are
+encouraged to change the options to new names if they have been changed locally.
 
 The path in looprpc "/v1/lsat/tokens" was renamed to "/v1/l402/tokens" and
 the corresponding method was renamed from `GetLsatTokens` to `GetL402Tokens`.