From 860012f16caac95ec36dd0e7cda36606213d7294 Mon Sep 17 00:00:00 2001
From: theborakompanioni <theborakompanioni+github@gmail.com>
Date: Sat, 2 Dec 2023 14:50:12 +0100
Subject: [PATCH] chore(ln): prevent lnd from syning indefinitely by mining a
 single block first

---
 .../integTest/resources/application-test.yml  |  2 ++
 .../setup/RegtestLightningNetworkSetup.java   | 31 ++++++++++++++-----
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/lightning-regtest/lightning-regtest-example-application/src/integTest/resources/application-test.yml b/lightning-regtest/lightning-regtest-example-application/src/integTest/resources/application-test.yml
index 4fb675565..ec52d986a 100644
--- a/lightning-regtest/lightning-regtest-example-application/src/integTest/resources/application-test.yml
+++ b/lightning-regtest/lightning-regtest-example-application/src/integTest/resources/application-test.yml
@@ -4,6 +4,8 @@ app.description: A spring boot bitcoin demo application
 spring.application.name: 'tbk-bitcoin-spring-boot-starter-demo (test)'
 spring.http.log-request-details: true
 
+logging.level.org.tbk: DEBUG
+
 spring.docker.compose:
   enabled: true
   file: ./../../docker/regtest/lightning-regtest-setup-devel/docker-compose.yml
diff --git a/lightning-regtest/lightning-regtest-setup/src/main/java/org/tbk/lightning/regtest/setup/RegtestLightningNetworkSetup.java b/lightning-regtest/lightning-regtest-setup/src/main/java/org/tbk/lightning/regtest/setup/RegtestLightningNetworkSetup.java
index e1d532561..18481a341 100644
--- a/lightning-regtest/lightning-regtest-setup/src/main/java/org/tbk/lightning/regtest/setup/RegtestLightningNetworkSetup.java
+++ b/lightning-regtest/lightning-regtest-setup/src/main/java/org/tbk/lightning/regtest/setup/RegtestLightningNetworkSetup.java
@@ -79,9 +79,19 @@ public void run() throws IOException {
     }
 
     private void beforeSetup() throws IOException {
-        onchainFaucet.init();
+        BitcoindRegtestTestHelper.createDefaultWalletIfNecessary(bitcoinClient);
+
+        // it seems to be necessary to mine a single block and wait for the nodes to synchronize.
+        // otherwise, LND seems to be stuck on regtest indefinitely (last check: 2023-12-02).
+        log.debug("Mine a single block and await node synchronization…");
+        bitcoinClient.generateToAddress(1, bitcoinClient.getNewAddress());
+        waitForNodesBlockHeightSynchronization();
+        log.debug("Mine a single block and await node synchronization: Done.");
 
+        log.debug("Initialize on-chain faucet and await node synchronization…");
+        onchainFaucet.init();
         waitForNodesBlockHeightSynchronization();
+        log.debug("Initialize on-chain faucet and await node synchronization: Done.");
     }
 
     private void afterSetup() {
@@ -123,7 +133,7 @@ private void setupPeers() {
                 CommonConnectResponse ignoredOnPurpose = connectPeers(entry.getT1(), entry.getT2());
                 log.debug("{} is connected to peer {}", originNodeName, targetNodeName);
             } catch (Exception e) {
-                // LND error if peer is already connected `UNKNOWN: already connected to peer: ${pubkey}@${ip}:${port}`
+                // LND error if peer is already connected: `UNKNOWN: already connected to peer: ${pubkey}@${ip}:${port}`
                 boolean isAlreadyConnected = e.getMessage().contains("already connected to peer");
                 if (!isAlreadyConnected) {
                     throw e;
@@ -347,12 +357,14 @@ private void waitForNodesBlockHeightSynchronization() throws IOException {
     // wait for cln nodes to catch up to the newest block height.
     // prevents `io.grpc.StatusRuntimeException: RpcError { code: Some(304), message: "Still syncing with bitcoin network" }`
     private static void waitForNodeBlockHeightSynchronization(BitcoinExtendedClient bitcoin, Collection<NodeInfo> lnNodes) throws IOException {
-        int currentBlockHeight = bitcoin.getBlockChainInfo().getBlocks();
+        BlockChainInfo blockChainInfo = bitcoin.getBlockChainInfo();
+        int currentBlockHeight = blockChainInfo.getBlocks();
 
-        // does not need to be more often than every 5 seconds - cln can take quite long to synchronize
+        // does not need to be more often than every 5 seconds - cln can take quite long to synchronize.
         Duration checkInterval = Duration.ofSeconds(5);
-        // cln sometimes takes up to ~30 seconds when catching up to more than 100 blocks
-        Duration timeout = Duration.ofSeconds(180);
+        // cln sometimes takes up to ~30 seconds when catching up to more than 100 blocks.
+        // lnd can take even longer as it fetches blocks every 1 seconds if it missed blocks via zmq.
+        Duration timeout = Duration.ofMinutes(3).plusSeconds(2L * currentBlockHeight);
 
         lnNodes.forEach(it -> waitForNodeBlockHeightSynchronization(it.getClient(), currentBlockHeight, checkInterval, timeout));
     }
@@ -367,10 +379,13 @@ private static void waitForNodeBlockHeightSynchronization(LightningCommonClient
                     try {
                         CommonInfoResponse info = requireNonNull(client.info(CommonInfoRequest.newBuilder().build())
                                 .block(Duration.ofSeconds(30)));
-                        boolean finished = info.getBlockheight() >= minBlockHeight;
+                        boolean hasSyncWarning = !info.getWarningBlockSync().isEmpty();
+                        boolean blockHeightInSync = info.getBlockheight() >= minBlockHeight;
+                        boolean finished = !hasSyncWarning && blockHeightInSync;
 
-                        log.debug("Waiting for blockheight to reach {} on {}, currently at height {}: {}",
+                        log.debug("Waiting for block height to reach {} on {}, currently at height {} (warning={}): {}",
                                 minBlockHeight, info.getAlias(), info.getBlockheight(),
+                                info.getWarningBlockSync(),
                                 finished ? "Done" : "Still waiting…");
 
                         return finished;