v4.ident.me is down, add alternatives (#210)

op-node-entrypoint

@@ -1,9 +1,30 @@
 #!/bin/bash
 set -eu
 
+get_public_ip() {
+  # Define a list of HTTP-based providers
+  local PROVIDERS=(
+    "http://ifconfig.me"
+    "http://api.ipify.org"
+    "http://ipecho.net/plain"
+    "http://v4.ident.me"
+  )
+  # Iterate through the providers until an IP is found or the list is exhausted
+  for provider in "${PROVIDERS[@]}"; do
+    local IP
+    IP=$(curl -s "$provider")
+    # Check if IP contains a valid format (simple regex for an IPv4 address)
+    if [[ $IP =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+      echo "$IP"
+      return 0
+    fi
+  done
+  return 1
+}
+
 if [[ -z "$OP_NODE_NETWORK" ]]; then
-    echo "expected OP_NODE_NETWORK to be set" 1>&2
-    exit 1
+  echo "expected OP_NODE_NETWORK to be set" 1>&2
+  exit 1
 fi
 
 # wait until local geth comes up (authed so will return 401 without token)
@@ -13,7 +34,12 @@ until [ "$(curl -s -w '%{http_code}' -o /dev/null "${OP_NODE_L2_ENGINE_RPC/ws/ht
 done
 
 # public-facing P2P node, advertise public IP address
-PUBLIC_IP=$(curl -s v4.ident.me)
+if PUBLIC_IP=$(get_public_ip); then
+  echo "fetched public IP is: $PUBLIC_IP"
+else
+  echo "Could not retrieve public IP."
+  exit 8
+fi
 export OP_NODE_P2P_ADVERTISE_IP=$PUBLIC_IP
 
 echo "$OP_NODE_L2_ENGINE_AUTH_RAW" > "$OP_NODE_L2_ENGINE_AUTH"