chore: add script to check required env variables

scripts/check-required-env.sh

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ENV_FILE="${1:-.env.mainnet}"
+
+REQUIRED_VARS=(
+  "OP_NODE_L1_ETH_RPC"
+  "OP_NODE_L1_BEACON"
+  "OP_NODE_L1_BEACON_ARCHIVER"
+  "OP_NODE_L1_RPC_KIND"
+)
+
+PLACEHOLDER_PATTERNS=(
+  "<your-preferred-l1-rpc>"
+  "<your-preferred-l1-beacon>"
+  "<your-preferred-l1-beacon-archiver>"
+)
+
+echo "Checking required L1 configuration variables in: ${ENV_FILE}"
+echo
+
+if [ ! -f "${ENV_FILE}" ]; then
+  echo "Error: file '${ENV_FILE}' does not exist."
+  echo "Pass a different file path as the first argument if needed."
+  exit 1
+fi
+
+missing=0
+placeholder=0
+
+get_var_line() {
+  local name="$1"
+  # Take the last assignment in the file if there are multiple
+  grep -E "^[[:space:]]*${name}=" "${ENV_FILE}" | tail -n 1 || true
+}
+
+strip_value() {
+  sed 's/^[[:space:]]*[A-Za-z0-9_]\{1,\}=[[:space:]]*//' | tr -d '"' | tr -d "'"
+}
+
+for var in "${REQUIRED_VARS[@]}"; do
+  line="$(get_var_line "${var}")"
+  if [ -z "${line}" ]; then
+    echo "Missing variable: ${var}"
+    missing=$((missing + 1))
+    continue
+  fi
+
+  value="$(printf '%s\n' "${line}" | strip_value)"
+
+  if [ -z "${value}" ]; then
+    echo "Empty value for: ${var}"
+    missing=$((missing + 1))
+    continue
+  fi
+
+  for pat in "${PLACEHOLDER_PATTERNS[@]}"; do
+    if printf '%s\n' "${value}" | grep -q "${pat}"; then
+      echo "Placeholder value detected for: ${var}"
+      placeholder=$((placeholder + 1))
+      break
+    fi
+  done
+done
+
+echo
+if [ "${missing}" -eq 0 ] && [ "${placeholder}" -eq 0 ]; then
+  echo "OK: all required variables are present and non-empty."
+  exit 0
+fi
+
+echo "Summary:"
+echo "  Missing or empty variables    : ${missing}"
+echo "  Variables with placeholder(s) : ${placeholder}"
+echo
+echo "Please update '${ENV_FILE}' with valid endpoints before running the node."
+exit 1