Add health check to wait for execution endpoint availability before starting validator

staking/Dockerfile

@@ -7,7 +7,7 @@ FROM nethermind/starknet-staking-v2:${UPSTREAM_VERSION} AS upstream
 FROM alpine:3.21
 
 # Install runtime deps
-RUN apk add --no-cache bash ca-certificates
+RUN apk add --no-cache bash ca-certificates curl
 
 # Copy the validator binary from the upstream stage
 COPY --from=upstream /ko-app/validator /app/validator

staking/entrypoint.sh

@@ -1,8 +1,67 @@
 #!/bin/bash
 set -e
 
+# Configuration for health check
+MAX_RETRIES=${HEALTH_CHECK_MAX_RETRIES:-360}  # 360 retries = 2 hours with 20s sleep
+SLEEP_INTERVAL=${HEALTH_CHECK_SLEEP_INTERVAL:-20}  # 20 seconds between retries
+TIMEOUT=${HEALTH_CHECK_TIMEOUT:-5}  # 5 seconds timeout for each health check
+
+# Validate configuration values are positive integers
+if ! [[ "$MAX_RETRIES" =~ ^[0-9]+$ ]] || [ "$MAX_RETRIES" -lt 1 ]; then
+  echo "✗ ERROR: HEALTH_CHECK_MAX_RETRIES must be a positive integer. Got: $MAX_RETRIES"
+  exit 1
+fi
+if ! [[ "$SLEEP_INTERVAL" =~ ^[0-9]+$ ]] || [ "$SLEEP_INTERVAL" -lt 1 ]; then
+  echo "✗ ERROR: HEALTH_CHECK_SLEEP_INTERVAL must be a positive integer. Got: $SLEEP_INTERVAL"
+  exit 1
+fi
+if ! [[ "$TIMEOUT" =~ ^[0-9]+$ ]] || [ "$TIMEOUT" -lt 1 ]; then
+  echo "✗ ERROR: HEALTH_CHECK_TIMEOUT must be a positive integer. Got: $TIMEOUT"
+  exit 1
+fi
+
 echo "Starting Starknet Staking Validator..."
 
+# Health check function
+# Note: We don't use --fail because any HTTP response (including 404) indicates
+# the endpoint is reachable and listening, which is what we need to verify
+check_endpoint_health() {
+  local url=$1
+  if curl --silent --max-time "${TIMEOUT}" "${url}" > /dev/null 2>&1; then
+    return 0
+  else
+    return 1
+  fi
+}
+
+# Wait for PROVIDER_HTTP_URL to be available
+if [ -z "${PROVIDER_HTTP_URL}" ]; then
+  echo "✗ ERROR: PROVIDER_HTTP_URL is not set. Cannot start validator without provider endpoint."
+  exit 1
+fi
+
+echo "Checking if provider endpoint is available: ${PROVIDER_HTTP_URL}"
+
+attempt=1
+while [ $attempt -le $MAX_RETRIES ]; do
+  echo "[Attempt ${attempt}/${MAX_RETRIES}] Checking endpoint health..."
+
+  if check_endpoint_health "${PROVIDER_HTTP_URL}"; then
+    echo "✓ Endpoint is healthy and ready!"
+    break
+  else
+    if [ $attempt -eq $MAX_RETRIES ]; then
+      echo "✗ ERROR: Endpoint not available after ${MAX_RETRIES} attempts. Exiting."
+      exit 1
+    fi
+    echo "✗ Endpoint not ready yet. Waiting ${SLEEP_INTERVAL} seconds before retry..."
+    sleep "${SLEEP_INTERVAL}"
+    attempt=$((attempt + 1))
+  fi
+done
+
+echo "Starting validator application..."
+
 exec /app/validator \
   --provider-http "${PROVIDER_HTTP_URL}" \
   --provider-ws "${PROVIDER_WS_URL}" \