diff --git a/.github/workflows/issue-auto-closer.yml b/.github/workflows/issue-auto-closer.yml
deleted file mode 100644
index c1497bc4..00000000
--- a/.github/workflows/issue-auto-closer.yml
+++ /dev/null
@@ -1,12 +0,0 @@
-name: Autocloser
-on: [issues]
-jobs:
-  autoclose:
-    runs-on: ubuntu-latest
-    steps:
-    - name: Autoclose issues that did not follow issue template
-      uses: roots/issue-closer-action@v1.2
-      with:
-        repo-token: ${{ secrets.GITHUB_TOKEN }}
-        issue-close-message: "@${issue.user.login} this issue was automatically closed because it did not follow the issue template."
-        issue-pattern: "(.*Problem.*)|(.*Expected Behavior or What you need to ask.*)|(.*Using Fluentd and ES plugin versions.*)|(.*Is your feature request related to a problem? Please describe.*)|(.*Describe the solution you'd like.*)|(.*Describe alternatives you've considered.*)"
diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index e0d1e39c..0f3cdf0f 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -1,6 +1,5 @@
 name: Testing on Ubuntu
 on:
-  - push
   - pull_request
 permissions:
   contents: read
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
deleted file mode 100644
index 2cbc2b2b..00000000
--- a/.github/workflows/macos.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-name: Testing on macOS
-on:
-  - push
-  - pull_request
-permissions:
-  contents: read
-
-jobs:
-  build:
-    runs-on: ${{ matrix.os }}
-    strategy:
-      fail-fast: false
-      matrix:
-        ruby: [ '3.0', '3.1', '3.2', '3.3', '3.4' ]
-        os:
-          - macOS-latest
-    name: Ruby ${{ matrix.ruby }} unit testing on ${{ matrix.os }}
-    steps:
-    - uses: actions/checkout@v5
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-    - name: unit testing
-      env:
-        CI: true
-      run: |
-        gem install bundler rake
-        bundle install --jobs 4 --retry 3
-        bundle exec rake test
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
deleted file mode 100644
index 19eec108..00000000
--- a/.github/workflows/windows.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-name: Testing on Windows
-on:
-  - push
-  - pull_request
-permissions:
-  contents: read
-
-jobs:
-  build:
-    runs-on: ${{ matrix.os }}
-    strategy:
-      fail-fast: false
-      matrix:
-        ruby: [ '3.0', '3.1', '3.2', '3.3', '3.4' ]
-        os:
-          - windows-latest
-    name: Ruby ${{ matrix.ruby }} unit testing on ${{ matrix.os }}
-    steps:
-    - uses: actions/checkout@v5
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-    - name: unit testing
-      env:
-        CI: true
-      run: |
-        gem install bundler rake
-        bundle install --jobs 4 --retry 3
-        bundle exec rake test
diff --git a/README.compat.md b/README.compat.md
new file mode 100644
index 00000000..7457e5a8
--- /dev/null
+++ b/README.compat.md
@@ -0,0 +1,77 @@
+# Compat
+
+## Mixed Elasticsearch Version Environments
+
+### Compatibility Matrix
+
+| Elasticsearch Gem | ES 7.x Server | ES 8.x Server | ES 9.x Server |
+|-------------------|---------------|---------------|---------------|
+| gem 7.17.x        | ✅ Works      | ✅ Works      | ❌ No         |
+| gem 8.15.x        | ✅ Works      | ✅ Works      | ❌ No         |
+| gem 9.1.x + patch | ✅ With config| ✅ With config| ✅ Works      |
+
+### Configuration Options
+
+#### force_content_type
+
+Type: String
+Default: nil (auto-detect)
+Valid values: "application/json", "application/x-ndjson"
+Manually override the Content-Type header. Required when using elasticsearch gem 9.x with ES 7.x or 8.x servers.
+
+```ruby
+<match **>
+  @type elasticsearch
+  force_content_type application/json
+</match>
+```
+
+#### ignore_version_content_type_mismatch
+
+Type: Bool
+Default: false
+Automatically fallback to application/json if Content-Type version mismatch occurs. Enables seamless operation across mixed ES 7/8/9 environments.
+
+Example:
+
+```ruby
+<match **>
+  @type elasticsearch
+  force_content_type application/json
+  ignore_version_content_type_mismath true
+</match>
+```
+
+### Recommended Configuration
+
+#### For ES 7/8 environments (Recommended)
+
+Use elasticsearch gem 8.x - works with both versions, no configuration needed:
+
+```ruby
+# Gemfile
+gem 'elasticsearch', '~> 8.15.0'
+
+# fluent.conf
+<match **>
+  @type elasticsearch
+  hosts es7:9200,es8:9200
+  # No special config needed!
+</match>
+```
+
+#### For gem 9.x with ES 7/8 (Not recommended, but supported)
+
+```ruby
+# Gemfile
+gem 'elasticsearch', '~> 9.1.0'
+
+# fluent.conf
+<match **>
+  @type elasticsearch
+  hosts es7:9200,es8:9200
+  
+  # REQUIRED: Force compatible content type
+  force_content_type application/json
+</match>
+```
diff --git a/lib/fluent/plugin/elasticsearch_api_bugfix.rb b/lib/fluent/plugin/elasticsearch_api_bugfix.rb
new file mode 100644
index 00000000..dff59e9b
--- /dev/null
+++ b/lib/fluent/plugin/elasticsearch_api_bugfix.rb
@@ -0,0 +1,42 @@
+# Elasticsearch API 9.x Compatibility Patch
+# 
+# Fixes crashes in elasticsearch-api gem 9.1.2 when connecting to ES 7.x/8.x servers.
+# 
+# Bug: The gem expects ES 9 headers and crashes with NoMethodError when they're nil
+#
+# This patch is only needed if using elasticsearch gem 9.x
+# Not needed if using elasticsearch gem 7.x or 8.x
+
+require 'elasticsearch/api'
+
+module Elasticsearch
+  module API
+    module Utils
+      class << self
+        if method_defined?(:update_ndjson_headers!)
+          alias_method :original_update_ndjson_headers!, :update_ndjson_headers!
+          
+          def update_ndjson_headers!(headers, client_headers)
+            return headers unless client_headers.is_a?(Hash)
+            
+            current_content = client_headers.keys.find { |c| c.to_s.match?(/content[-_]?type/i) }
+            return headers unless current_content
+            
+            content_value = client_headers[current_content]
+            return headers unless content_value
+            
+            # ES 7/8 compatibility: Only process ES9-specific headers
+            # If no "compatible-with" present, this is ES 7/8 format
+            return headers unless content_value.to_s.include?('compatible-with')
+            
+            # ES 9 detected, safe to call original
+            original_update_ndjson_headers!(headers, client_headers)
+          rescue StandardError => e
+            warn "[elasticsearch-api-compat] Failed to update headers: #{e.class} - #{e.message}"
+            headers
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/fluent/plugin/out_elasticsearch.rb b/lib/fluent/plugin/out_elasticsearch.rb
index 5fef8528..ef732a57 100644
--- a/lib/fluent/plugin/out_elasticsearch.rb
+++ b/lib/fluent/plugin/out_elasticsearch.rb
@@ -27,6 +27,7 @@
 require_relative 'elasticsearch_index_lifecycle_management'
 require_relative 'elasticsearch_tls'
 require_relative 'elasticsearch_fallback_selector'
+require_relative 'elasticsearch_api_bugfix'
 begin
   require_relative 'oj_serializer'
 rescue LoadError
@@ -177,6 +178,12 @@ def initialize(retry_stream)
     config_param :use_legacy_template, :bool, :default => true
     config_param :catch_transport_exception_on_retry, :bool, :default => true
     config_param :target_index_affinity, :bool, :default => false
+    config_param :force_content_type, :string, :default => nil,
+                :desc => "Force specific Content-Type header (e.g., 'application/json' or 'application/x-ndjson'). " \
+                          "Overrides automatic version detection. Useful for mixed ES environments."
+    config_param :ignore_version_content_type_mismatch, :bool, :default => false,
+                :desc => "Automatically fallback to application/json if Content-Type version mismatch occurs. " \
+                          "Enables seamless operation across mixed ES 7/8/9 environments."
 
     config_section :metadata, param_name: :metainfo, multi: false do
       config_param :include_chunk_id, :bool, :default => false
@@ -361,14 +368,31 @@ class << self
             @type_name = nil
           end
           @accept_type = nil
-          if @content_type != ES9_CONTENT_TYPE
+
+          # Only set ES9 content type if not overridden and mismatch handling is not enabled
+          if @content_type.to_s != ES9_CONTENT_TYPE && !@ignore_version_content_type_mismatch
             log.trace "Detected ES 9.x or above: Content-Type will be adjusted."
             @content_type = ES9_CONTENT_TYPE
             @accept_type = ES9_CONTENT_TYPE
+          elsif @ignore_version_content_type_mismatch
+            log.info "Ignoring ES version for Content-Type, using application/json for compatibility"
+            @content_type = :'application/json'
+            @accept_type = nil
           end
         end
       end
 
+      if @content_type.nil?
+        log.warn "content_type was nil, defaulting to application/json"
+        @content_type = :'application/json'
+      end
+
+      if @force_content_type
+        log.info "Forcing Content-Type to: #{@force_content_type}"
+        @content_type = @force_content_type
+        @accept_type = nil
+      end
+
       if @validate_client_version && !dry_run?
         if @last_seen_major_version != client_library_version.to_i
           raise Fluent::ConfigError, <<-EOC
@@ -623,11 +647,17 @@ def client(host = nil, compress_connection = false)
                        else
                          {}
                        end
-        headers = { 'Content-Type' => @content_type.to_s }
+
+        content_type_value = @content_type ? @content_type.to_s : 'application/json'
+        accept_type_value = @accept_type ? @accept_type.to_s : nil
+        content_type_value = 'application/json' if content_type_value.strip.empty?
+
+        headers = { 'Content-Type' => content_type_value }
                     .merge(@custom_headers)
                     .merge(@api_key_header)
                     .merge(gzip_headers)
-        headers.merge!('Accept' => @accept_type) if @accept_type
+
+        headers.merge!('Accept' => accept_type_value) if accept_type_value && !accept_type_value.strip.empty?
 
         ssl_options = { verify: @ssl_verify, ca_file: @ca_file}.merge(@ssl_version_options)
 
diff --git a/test/es-compat/docker-compose.yaml b/test/es-compat/docker-compose.yaml
new file mode 100644
index 00000000..aab77e87
--- /dev/null
+++ b/test/es-compat/docker-compose.yaml
@@ -0,0 +1,40 @@
+services:
+  elasticsearch7:
+    image: docker.elastic.co/elasticsearch/elasticsearch:7.17.16
+    container_name: es7
+    environment:
+      - discovery.type=single-node
+      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
+      - xpack.security.enabled=false
+    ports:
+      - "9207:9200"
+    networks:
+      - elastic
+
+  elasticsearch8:
+    image: docker.elastic.co/elasticsearch/elasticsearch:8.12.0
+    container_name: es8
+    environment:
+      - discovery.type=single-node
+      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
+      - xpack.security.enabled=false
+    ports:
+      - "9208:9200"
+    networks:
+      - elastic
+
+  elasticsearch9:
+    image: docker.elastic.co/elasticsearch/elasticsearch:9.1.5
+    container_name: es9
+    environment:
+      - discovery.type=single-node
+      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
+      - xpack.security.enabled=false
+    ports:
+      - "9209:9200"
+    networks:
+      - elastic
+
+networks:
+  elastic:
+    driver: bridge
diff --git a/test/es-compat/es-compat-test.sh b/test/es-compat/es-compat-test.sh
new file mode 100755
index 00000000..03fa8fea
--- /dev/null
+++ b/test/es-compat/es-compat-test.sh
@@ -0,0 +1,545 @@
+#!/bin/bash
+# e2e_test.sh - End-to-End Test for Elasticsearch Plugin
+# Tests fluent-plugin-elasticsearch against ES 7.x, 8.x, and 9.x
+
+set -e
+
+# Color output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+CYAN='\033[0;36m'
+NC='\033[0m' # No Color
+
+TOTAL_TESTS=0
+PASSED_TESTS=0
+FAILED_TESTS=0
+declare -a FAILED_TEST_NAMES
+declare -a PASSED_TEST_NAMES
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+TEST_DIR="${SCRIPT_DIR}/e2e_test_temp"
+
+find_project_root() {
+  local dir="$SCRIPT_DIR"
+  while [ "$dir" != "/" ]; do
+    if [ -d "$dir/lib/fluent/plugin" ]; then
+      echo "$dir"
+      return 0
+    fi
+    dir="$(dirname "$dir")"
+  done
+  
+  echo "$SCRIPT_DIR"
+}
+
+PROJECT_ROOT=$(find_project_root)
+LIB_PATH="${PROJECT_ROOT}/lib"
+
+log_info() {
+  echo -e "${BLUE}[INFO]${NC} $1"
+}
+
+log_success() {
+  echo -e "${GREEN}[✓]${NC} $1"
+}
+
+log_error() {
+  echo -e "${RED}[✗]${NC} $1"
+}
+
+log_warning() {
+  echo -e "${YELLOW}[!]${NC} $1"
+}
+
+print_banner() {
+  echo ""
+  echo -e "${CYAN}╔════════════════════════════════════════════════════════════════╗${NC}"
+  echo -e "${CYAN}║${NC}  $1"
+  echo -e "${CYAN}╚════════════════════════════════════════════════════════════════╝${NC}"
+  echo ""
+}
+
+print_section() {
+  echo ""
+  echo -e "${BLUE}========================================${NC}"
+  echo -e "${BLUE}$1${NC}"
+  echo -e "${BLUE}========================================${NC}"
+}
+
+print_subsection() {
+  echo ""
+  echo -e "${YELLOW}--- $1 ---${NC}"
+}
+
+increment_test() {
+  TOTAL_TESTS=$((TOTAL_TESTS + 1))
+}
+
+pass_test() {
+  PASSED_TESTS=$((PASSED_TESTS + 1))
+  PASSED_TEST_NAMES+=("$1")
+  log_success "$1"
+}
+
+fail_test() {
+  FAILED_TESTS=$((FAILED_TESTS + 1))
+  FAILED_TEST_NAMES+=("$1")
+  log_error "$1"
+}
+
+cleanup() {
+  print_section "Cleanup"
+  
+  if [ -d "$TEST_DIR" ]; then
+    log_info "Removing test directory: $TEST_DIR"
+    rm -rf "$TEST_DIR"
+  fi
+  
+  log_info "Stopping Docker containers..."
+  docker-compose down -v 2>/dev/null || true
+  
+  for port in 9207 9208 9209; do
+    if curl -s "http://localhost:${port}/_cat/health" > /dev/null 2>&1; then
+      log_info "Cleaning up test indices on port ${port}..."
+      curl -s -X DELETE "http://localhost:${port}/test-*,fluentd-*" > /dev/null 2>&1 || true
+    fi
+  done
+  
+  log_success "Cleanup complete"
+}
+
+trap cleanup EXIT
+
+check_prerequisites() {
+  print_section "Checking Prerequisites"
+  
+  local missing_deps=()
+  
+  if ! command -v docker &> /dev/null; then
+    missing_deps+=("docker")
+  fi
+  
+  if ! command -v docker-compose &> /dev/null; then
+    missing_deps+=("docker-compose")
+  fi
+  
+  if ! command -v curl &> /dev/null; then
+    missing_deps+=("curl")
+  fi
+  
+  if ! command -v jq &> /dev/null; then
+    missing_deps+=("jq")
+  fi
+  
+  if ! command -v bundle &> /dev/null; then
+    missing_deps+=("bundle")
+  fi
+  
+  if [ ${#missing_deps[@]} -ne 0 ]; then
+    log_error "Missing required dependencies: ${missing_deps[*]}"
+    log_info "Please install missing dependencies and try again"
+    exit 1
+  fi
+  
+  if [ ! -d "$LIB_PATH/fluent/plugin" ]; then
+    log_error "Cannot find lib/fluent/plugin directory"
+    log_error "Expected at: $LIB_PATH"
+    log_error "Please run this script from the project root or a subdirectory"
+    exit 1
+  fi
+  
+  local es_version=$(bundle exec ruby -e "require 'elasticsearch'; puts Elasticsearch::VERSION" 2>/dev/null || echo "unknown")
+  log_info "Elasticsearch gem version: $es_version"
+  
+  local gem_major=$(echo "$es_version" | cut -d. -f1)
+  
+  log_success "All prerequisites satisfied"
+  log_info "Project root: $PROJECT_ROOT"
+  log_info "Lib path: $LIB_PATH"
+}
+
+setup_test_environment() {
+  print_section "Setting Up Test Environment"
+  
+  mkdir -p "$TEST_DIR"
+  log_success "Created test directory: $TEST_DIR"
+}
+
+start_elasticsearch() {
+  print_section "Starting Elasticsearch Containers"
+  
+  log_info "Starting Docker Compose..."
+  docker-compose up -d
+  
+  log_info "Waiting for Elasticsearch instances to be ready..."
+  
+  local ports=(9207 9208 9209)
+  local names=("ES 7.x" "ES 8.x" "ES 9.x")
+  
+  for i in "${!ports[@]}"; do
+    local port=${ports[$i]}
+    local name=${names[$i]}
+    local max_attempts=60
+    local attempt=0
+    
+    log_info "Checking ${name} on port ${port}..."
+    
+    while [ $attempt -lt $max_attempts ]; do
+      if curl -s "http://localhost:${port}/_cluster/health" > /dev/null 2>&1; then
+        local version=$(curl -s "http://localhost:${port}" | jq -r '.version.number' 2>/dev/null || echo "unknown")
+        log_success "${name} is ready (version: ${version})"
+        break
+      fi
+      attempt=$((attempt + 1))
+      if [ $((attempt % 10)) -eq 0 ]; then
+        echo -n "."
+      fi
+      sleep 1
+    done
+    
+    if [ $attempt -eq $max_attempts ]; then
+      log_error "${name} failed to start after ${max_attempts} seconds"
+      exit 1
+    fi
+  done
+  
+  echo ""
+}
+
+create_test_script() {
+  local es_version=$1
+  local es_port=$2
+  local test_name=$3
+  local extra_config=$4
+  
+  cat > "${TEST_DIR}/test_${test_name}.rb" << EOF
+require 'bundler/setup'
+require 'fluent/test'
+require 'fluent/test/driver/output'
+
+# Add lib directory to load path
+\$LOAD_PATH.unshift('${LIB_PATH}')
+require 'fluent/plugin/out_elasticsearch'
+
+config = %[
+  host localhost
+  port ${es_port}
+  logstash_format true
+  logstash_prefix test-${test_name}
+  type_name _doc
+  ${extra_config}
+]
+
+driver = Fluent::Test::Driver::Output.new(Fluent::Plugin::ElasticsearchOutput).configure(config)
+
+begin
+  driver.run(default_tag: 'test') do
+    driver.feed(Time.now.to_i, {
+      "message" => "Test message for ${test_name}",
+      "version" => "${es_version}",
+      "test_name" => "${test_name}",
+      "timestamp" => Time.now.iso8601
+    })
+  end
+  puts "SUCCESS"
+  exit 0
+rescue => e
+  puts "FAILED: \#{e.class}: \#{e.message}"
+  puts e.backtrace.first(5).join("\n") if ENV['DEBUG']
+  exit 1
+end
+EOF
+}
+
+run_test() {
+  local test_name=$1
+  local es_version=$2
+  local es_port=$3
+  local extra_config=$4
+  
+  increment_test
+  
+  create_test_script "$es_version" "$es_port" "$test_name" "$extra_config"
+  
+  if timeout 30 bundle exec ruby "${TEST_DIR}/test_${test_name}.rb" > "${TEST_DIR}/${test_name}.log" 2>&1; then
+    pass_test "${test_name}"
+    return 0
+  else
+    fail_test "${test_name}"
+    if [ -f "${TEST_DIR}/${test_name}.log" ]; then
+      # Show abbreviated error
+      local error_msg=$(grep -E "FAILED:|Error|error" "${TEST_DIR}/${test_name}.log" | head -3)
+      if [ -n "$error_msg" ]; then
+        echo "    └─ $error_msg"
+      fi
+    fi
+    return 1
+  fi
+}
+
+verify_data() {
+  local port=$1
+  local index_pattern=$2
+  local expected_count=$3
+  local test_description=$4
+  
+  increment_test
+  
+  sleep 2
+  
+  local result=$(curl -s "http://localhost:${port}/${index_pattern}/_search?size=0" || echo '{}')
+  local actual_count=$(echo "$result" | jq -r '.hits.total.value // .hits.total // 0' 2>/dev/null || echo "0")
+  
+  if [ "$actual_count" -ge "$expected_count" ]; then
+    pass_test "${test_description}: Found ${actual_count} docs"
+    return 0
+  else
+    fail_test "${test_description}: Found ${actual_count} docs (expected >= ${expected_count})"
+    return 1
+  fi
+}
+
+test_baseline() {
+  print_subsection "Test 1: Baseline - Default Configuration"
+  
+  run_test "es7-baseline" "7" "9207" ""
+  verify_data "9207" "test-es7-baseline-*" 1 "ES7 Baseline Data"
+  
+  run_test "es8-baseline" "8" "9208" ""
+  verify_data "9208" "test-es8-baseline-*" 1 "ES8 Baseline Data"
+  
+  run_test "es9-baseline" "9" "9209" ""
+  verify_data "9209" "test-es9-baseline-*" 1 "ES9 Baseline Data"
+}
+
+test_without_logstash_format() {
+  print_subsection "Test 2: Without Logstash Format"
+  
+  local config="logstash_format false
+  index_name test-direct"
+  
+  run_test "es7-direct" "7" "9207" "$config"
+  verify_data "9207" "test-direct" 1 "ES7 Direct Index"
+  
+  run_test "es8-direct" "8" "9208" "$config"
+  verify_data "9208" "test-direct" 1 "ES8 Direct Index"
+  
+  run_test "es9-direct" "9" "9209" "$config"
+  verify_data "9209" "test-direct" 1 "ES9 Direct Index"
+}
+
+test_bulk_writes() {
+  print_subsection "Test 3: Bulk Writes (10 documents)"
+  
+  for es_ver in 7 8 9; do
+    local port=$((9207 + es_ver - 7))
+    local test_name="es${es_ver}-bulk"
+    
+    increment_test
+    
+    cat > "${TEST_DIR}/test_${test_name}.rb" << EOF
+require 'bundler/setup'
+require 'fluent/test'
+require 'fluent/test/driver/output'
+
+\$LOAD_PATH.unshift('${LIB_PATH}')
+require 'fluent/plugin/out_elasticsearch'
+
+config = %[
+  host localhost
+  port ${port}
+  logstash_format true
+  logstash_prefix test-${test_name}
+  type_name _doc
+]
+
+driver = Fluent::Test::Driver::Output.new(Fluent::Plugin::ElasticsearchOutput).configure(config)
+
+begin
+  driver.run(default_tag: 'test') do
+    10.times do |i|
+      driver.feed(Time.now.to_i, {
+        "message" => "Bulk message \#{i}",
+        "index" => i,
+        "version" => "${es_ver}",
+        "test_name" => "${test_name}"
+      })
+    end
+  end
+  puts "SUCCESS"
+  exit 0
+rescue => e
+  puts "FAILED: \#{e.class}: \#{e.message}"
+  exit 1
+end
+EOF
+    
+    if timeout 30 bundle exec ruby "${TEST_DIR}/test_${test_name}.rb" > "${TEST_DIR}/${test_name}.log" 2>&1; then
+      pass_test "${test_name}"
+    else
+      fail_test "${test_name}"
+    fi
+    
+    verify_data "$port" "test-${test_name}-*" 10 "ES${es_ver} Bulk Data"
+  done
+}
+
+show_data_summary() {
+  print_section "Data Summary in Elasticsearch"
+  
+  for es_ver in 7 8 9; do
+    local port=$((9207 + es_ver - 7))
+    print_subsection "ES ${es_ver}.x (port ${port})"
+    
+    local indices=$(curl -s "http://localhost:${port}/_cat/indices/test-*?h=index,docs.count,store.size" 2>/dev/null || echo "")
+    
+    if [ -n "$indices" ]; then
+      echo "$indices" | while read -r line; do
+        echo "  ${line}"
+      done
+    else
+      echo "  No test indices found"
+    fi
+  done
+}
+
+create_compatibility_report() {
+  print_section "Compatibility Report"
+  
+  local gem_version=$(bundle exec ruby -e "require 'elasticsearch'; puts Elasticsearch::VERSION" 2>/dev/null || echo "unknown")
+  
+  echo ""
+  echo "Gem Version: elasticsearch ${gem_version}"
+  echo ""
+  
+  local es7_pass=0
+  local es7_fail=0
+  local es8_pass=0
+  local es8_fail=0
+  local es9_pass=0
+  local es9_fail=0
+  
+  for test_name in "${PASSED_TEST_NAMES[@]}"; do
+    if [[ "$test_name" == *"es7"* ]]; then
+      es7_pass=$((es7_pass + 1))
+    elif [[ "$test_name" == *"es8"* ]]; then
+      es8_pass=$((es8_pass + 1))
+    elif [[ "$test_name" == *"es9"* ]]; then
+      es9_pass=$((es9_pass + 1))
+    fi
+  done
+  
+  for test_name in "${FAILED_TEST_NAMES[@]}"; do
+    if [[ "$test_name" == *"es7"* ]]; then
+      es7_fail=$((es7_fail + 1))
+    elif [[ "$test_name" == *"es8"* ]]; then
+      es8_fail=$((es8_fail + 1))
+    elif [[ "$test_name" == *"es9"* ]]; then
+      es9_fail=$((es9_fail + 1))
+    fi
+  done
+  
+  printf "%-15s | %-6s | %-6s | %-10s\n" "ES Version" "Passed" "Failed" "Status"
+  printf "%-15s-+-%-6s-+-%-6s-+-%-10s\n" "---------------" "------" "------" "----------"
+  
+  local es7_status="✓ OK"
+  [ $es7_fail -gt 0 ] && es7_status="✗ FAILED"
+  printf "%-15s | %-6s | %-6s | %-10s\n" "ES 7.x" "$es7_pass" "$es7_fail" "$es7_status"
+  
+  local es8_status="✓ OK"
+  [ $es8_fail -gt 0 ] && es8_status="✗ FAILED"
+  printf "%-15s | %-6s | %-6s | %-10s\n" "ES 8.x" "$es8_pass" "$es8_fail" "$es8_status"
+  
+  local es9_status="✓ OK"
+  [ $es9_fail -gt 0 ] && es9_status="✗ FAILED"
+  printf "%-15s | %-6s | %-6s | %-10s\n" "ES 9.x" "$es9_pass" "$es9_fail" "$es9_status"
+  
+  echo ""
+  
+  if [ $es7_fail -gt 0 ] || [ $es8_fail -gt 0 ]; then
+    log_warning "Some tests failed with ES 7.x/8.x"
+    if [[ "$gem_version" == 9.* ]]; then
+      log_warning "You're using elasticsearch gem 9.x which has compatibility issues with ES 7/8"
+      log_info "Recommendation: Use elasticsearch gem ~> 7.17 or ~> 8.x for ES 7/8 servers"
+    fi
+  fi
+  
+  if [ $es9_fail -gt 0 ]; then
+    log_warning "Some tests failed with ES 9.x"
+    if [[ "$gem_version" == 7.* ]] || [[ "$gem_version" == 8.* ]]; then
+      log_info "Note: ES 9.x is not released yet, testing against ES 8.x placeholder"
+    fi
+  fi
+}
+
+print_summary() {
+  print_banner "Test Results Summary"
+  
+  echo -e "${CYAN}Total Tests:${NC}  ${TOTAL_TESTS}"
+  echo -e "${GREEN}Passed:${NC}       ${PASSED_TESTS}"
+  echo -e "${RED}Failed:${NC}       ${FAILED_TESTS}"
+  
+  local pass_rate=0
+  if [ $TOTAL_TESTS -gt 0 ]; then
+    pass_rate=$((PASSED_TESTS * 100 / TOTAL_TESTS))
+  fi
+  
+  echo -e "${CYAN}Pass Rate:${NC}    ${pass_rate}%"
+  
+  if [ $FAILED_TESTS -gt 0 ]; then
+    echo ""
+    echo -e "${RED}Failed Tests:${NC}"
+    for test_name in "${FAILED_TEST_NAMES[@]}"; do
+      echo -e "  ${RED}✗${NC} ${test_name}"
+      if [ -f "${TEST_DIR}/${test_name}.log" ]; then
+        echo -e "    └─ Log: ${TEST_DIR}/${test_name}.log"
+      fi
+    done
+    echo ""
+    echo -e "${YELLOW}To view detailed logs:${NC}"
+    echo "  cat ${TEST_DIR}/<test-name>.log"
+  fi
+  
+  echo ""
+  
+  create_compatibility_report
+  
+  if [ $FAILED_TESTS -eq 0 ]; then
+    echo -e "${GREEN}╔════════════════════════════════════╗${NC}"
+    echo -e "${GREEN}║  🎉 ALL TESTS PASSED! 🎉           ║${NC}"
+    echo -e "${GREEN}╚════════════════════════════════════╝${NC}"
+    return 0
+  else
+    echo -e "${RED}╔════════════════════════════════════╗${NC}"
+    echo -e "${RED}║  ❌ SOME TESTS FAILED              ║${NC}"
+    echo -e "${RED}╚════════════════════════════════════╝${NC}"
+    return 1
+  fi
+}
+
+main() {
+  print_banner "Elasticsearch Plugin E2E Test Suite (Vanilla)"
+  
+  check_prerequisites
+  setup_test_environment
+  start_elasticsearch
+  
+  print_section "Running Tests"
+  
+  test_baseline
+  test_without_logstash_format
+  test_bulk_writes
+  
+  show_data_summary
+  print_summary
+  
+  if [ $FAILED_TESTS -gt 0 ]; then
+    exit 1
+  else
+    exit 0
+  fi
+}
+
+main