Bridge: fix daemon stop when encounter error submitting stellar tx (#920

)

* update cargo.lock file

* fix: pre-check wallet and continue on stellar error

* fix go fmt

bridge/docs/observability.md

@@ -66,7 +66,8 @@ For example, if a customer is complaining that their deposit never bridged, you
 - `event_burn_tx_ready_received`: The bridge instance has received TFChain `BurnTransactionReady` event which means all bridge validators signed a withdraw transaction.
 - `event_burn_tx_expired_received`: The bridge instance has received TFChain `BurnTransactionExpired` event.
 - `withdraw_skipped`: a refund request skipped by the bridge instance as it has already been refunded.
-- `withdraw_proposed`: a withdraw has proposed or signed by the bridge instance. 
+- `withdraw_proposed`: a withdraw has proposed or signed by the bridge instance.
+- `withdraw_postponed`: a withdraw has postponed due to a problem in sending this transaction to the stellar network and will be retried later.
 - `withdraw_completed`: a withdraw has completed and received on the target stellar account.
 
 ##### Bridge vault account related
@@ -787,6 +788,32 @@ the source field set contains all fields which are included in the source object
     </tbody>
 </table>
 
+##### withdraw_postponed
+
+- kind: event
+
+- category: withdraw
+
+<table>
+    <thead>
+        <tr><th colspan="4"><div>withdraw_postponed Event Properties</div></th></tr>
+        <tr>
+            <th>Property</th>
+            <th>Type</th>
+            <th>Required</th>
+            <th>Description</th>
+        </tr>
+    </thead>
+    <tbody>
+        <tr>
+            <td><code>reason</code></td>
+            <td>string</td>
+            <td>yes</td>
+            <td>The reason behind the postponed of this transfer. </td>
+        </tr>     
+    </tbody>
+</table>
+
 ##### withdraw_completed
 
 - kind: event

bridge/tfchain_bridge/pkg/bridge/bridge.go

@@ -2,6 +2,7 @@ package bridge
 
 import (
 	"context"
+	"strconv"
 	"time"
 
 	"github.com/pkg/errors"
@@ -13,7 +14,8 @@ import (
 )
 
 const (
-	BridgeNetwork = "stellar"
+	BridgeNetwork  = "stellar"
+	MinimumBalance = 0
 )
 
 // Bridge is a high lvl structure which listens on contract events and bridge-related
@@ -73,7 +75,29 @@ func NewBridge(ctx context.Context, cfg pkg.BridgeConfig) (*Bridge, string, erro
 	return bridge, wallet.GetKeypair().Address(), nil
 }
 
+func (bridge *Bridge) preCheckBalance(ctx context.Context) error {
+	balance, err := bridge.wallet.StatBridgeAccount()
+
+	if err != nil {
+		return errors.Wrap(err, "can't retrieve the wallet balance at the moment")
+	}
+	s, err := strconv.ParseFloat(balance, 64)
+	if err != nil {
+		return errors.Wrap(err, "can't parse the wallet balance")
+	}
+
+	if s < MinimumBalance {
+		return errors.Errorf("wallet balance insufficient: %s", balance)
+	}
+	return nil
+}
+
 func (bridge *Bridge) Start(ctx context.Context) error {
+	// pre-check wallet balance
+	if err := bridge.preCheckBalance(ctx); err != nil {
+		return err
+	}
+
 	log.Info().
 		Str("event_action", "bridge_started").
 		Str("event_kind", "event").

bridge/tfchain_bridge/pkg/bridge/withdraw.go

@@ -116,7 +116,16 @@ func (bridge *Bridge) handleWithdrawReady(ctx context.Context, withdrawReady sub
 	// todo add memo hash
 	err = bridge.wallet.CreatePaymentWithSignaturesAndSubmit(ctx, burnTx.Target, uint64(burnTx.Amount), fmt.Sprint(withdrawReady.ID), burnTx.Signatures, int64(burnTx.SequenceNumber))
 	if err != nil {
-		return err
+		// we can log and skip here as we could depend on tfcahin retry mechanism
+		// to notify us again about related burn tx
+		logger.Info().
+			Str("event_action", "withdraw_postponed").
+			Str("event_kind", "event").
+			Str("category", "withdraw").
+			Dict("metadata", zerolog.Dict().
+				Str("reason", err.Error())).
+			Msgf("the withdraw has been postponed due to a problem in sending this transaction to the stellar network. error was %s", err.Error())
+		return nil
 	}
 	logger.Info().
 		Str("event_action", "withdraw_completed").

bridge/tfchain_bridge/pkg/stellar/stellar.go

@@ -579,5 +579,5 @@ func (w *StellarWallet) StatBridgeAccount() (string, error) {
 			return balance.Balance, nil
 		}
 	}
-	return "", nil
+	return "", errors.New("source account does not have trustline")
 }