poll for RPC socket availability before launching ln nodes

recipes/cookbook/scaffold/docker/_aux/runtime/lib/utils.sh

@@ -1,2 +1,22 @@
 #!/usr/bin/env bash
 
+echo_err() {
+  printf "\e[31m%s\e[0m\n" "$*" >&2;
+}
+
+wait_for_socket() {
+  local port=${1:?required}
+  local host=${2:-localhost}
+  local max=${3:-100}
+  local delay=${4:-1}
+
+  local counter=1
+  while ! nc -z "$host" "$port" > /dev/null 2>&1; do
+    sleep ${delay}
+    ((++counter))
+    if [[ ${counter} -gt ${max} ]]; then
+      echo_err "socket '$host:$port' didn't come online in time"
+      return 1
+    fi
+  done
+}

recipes/cookbook/scaffold/docker/lightning/home/start.sh

@@ -1,7 +1,10 @@
 #!/usr/bin/env bash
 
-# give bitcoin nodes some head start
-# TODO: revisit this
-sleep 10
+. lib/utils.sh
+
+# wait for bitcoin node to open its RPC interface
+LIGHTNING_BITCOIN_RPC_HOST=${LIGHTNING_BITCOIN_RPC_HOST:?required}
+BITCOIN_RPC_PORT=${BITCOIN_RPC_PORT:?required}
+wait_for_socket "$BITCOIN_RPC_PORT" "$LIGHTNING_BITCOIN_RPC_HOST"
 
 exec lightningd.sh

recipes/cookbook/scaffold/docker/lnd/home/start.sh

@@ -1,10 +1,13 @@
 #!/usr/bin/env bash
 
-# give bitcoin nodes some head start
-# TODO: revisit this
-sleep 10
+. lib/utils.sh
 
 # wait for shared certificate creation
 while [[ ! -f /certs/rpc.cert ]]; do sleep 1; done
 
+# wait for bitcoin node to open its RPC interface
+LND_BITCOIN_RPC_HOST=${LND_BITCOIN_RPC_HOST:?required}
+BITCOIN_RPC_PORT=${BITCOIN_RPC_PORT:?required}
+wait_for_socket "$BITCOIN_RPC_PORT" "$LND_BITCOIN_RPC_HOST"
+
 exec lnd.sh