Graylog Logging Setup for Web Application

Setting Up Logging (Graylog) for Your Web Application

Graylog occupies a niche between ELK (powerful, complex) and Loki (simple, limited). Built-in web interface with search, alerting, and dashboard — no Kibana as a separate component. Perfect for teams needing centralized log management without deep customization.

Architecture: Graylog ← MongoDB (configuration) + OpenSearch/Elasticsearch (data)

Deployment

# docker-compose.yml
version: '3.8'
services:
  mongodb:
    image: mongo:6.0
    volumes:
      - mongo_data:/data/db

  opensearch:
    image: opensearchproject/opensearch:2.12.0
    environment:
      - cluster.name=graylog
      - discovery.type=single-node
      - plugins.security.disabled=true
      - "OPENSEARCH_JAVA_OPTS=-Xms2g -Xmx2g"
      - bootstrap.memory_lock=true
    ulimits:
      memlock: { soft: -1, hard: -1 }
    volumes:
      - os_data:/usr/share/opensearch/data

  graylog:
    image: graylog/graylog:6.0
    environment:
      - GRAYLOG_PASSWORD_SECRET=your_random_64_char_secret
      # echo -n "admin_password" | sha256sum
      - GRAYLOG_ROOT_PASSWORD_SHA2=your_sha256_password_hash
      - GRAYLOG_HTTP_EXTERNAL_URI=http://graylog.example.com:9000/
      - GRAYLOG_MONGODB_URI=mongodb://mongodb:27017/graylog
      - GRAYLOG_ELASTICSEARCH_HOSTS=http://opensearch:9200
    ports:
      - "9000:9000"     # Web UI
      - "12201:12201"   # GELF UDP
      - "12201:12201/udp"
      - "5044:5044"     # Beats
      - "514:514/udp"   # Syslog UDP
    depends_on:
      - mongodb
      - opensearch

volumes:
  mongo_data:
  os_data:

Generate GRAYLOG_PASSWORD_SECRET:

pwgen -N 1 -s 96

Hash the password:

echo -n "your_admin_password" | sha256sum | awk '{print $1}'

Input Sources (Inputs)

Graylog receives logs through Inputs — configured in System → Inputs:

GELF UDP (recommended for applications):

• Port: 12201
• Possible loss at high load (UDP), but minimal overhead

GELF TCP (more reliable):

• Port: 12201
• Use if delivery guarantee is critical

Beats (for Filebeat):

• Port: 5044

Syslog UDP/TCP:

• For system logs and network equipment

Sending Logs from Laravel

Via GELF (Graylog's native protocol):

composer require graylog2/gelf-php

// app/Logging/GraylogLogger.php
namespace App\Logging;

use Gelf\Publisher;
use Gelf\Transport\UdpTransport;
use Monolog\Handler\GelfHandler;
use Monolog\Logger;

class GraylogLogger
{
    public function __invoke(array $config): Logger
    {
        $transport = new UdpTransport(
            $config['host'],
            $config['port'] ?? 12201,
            UdpTransport::CHUNK_SIZE_LAN
        );
        $publisher = new Publisher($transport);
        $handler = new GelfHandler($publisher);

        return new Logger('app', [$handler]);
    }
}

// config/logging.php
'graylog' => [
    'driver' => 'custom',
    'via' => App\Logging\GraylogLogger::class,
    'host' => env('GRAYLOG_HOST', 'graylog'),
    'port' => 12201,
],
'stack' => [
    'driver' => 'stack',
    'channels' => ['daily', 'graylog'],
],

Context fields automatically become fields in Graylog:

Log::error('Payment failed', [
    'user_id' => $user->id,
    'order_id' => $order->id,
    'amount' => $order->amount,
    'provider_error' => $response->error,
]);

Filebeat for Nginx Logs

# /etc/filebeat/filebeat.yml
filebeat.inputs:
  - type: log
    paths: [/var/log/nginx/access.log]
    fields:
      source_type: nginx_access

processors:
  - add_fields:
      target: ''
      fields:
        environment: production

output.logstash:
  hosts: ["graylog-server:5044"]

Extractors and Pipelines

Graylog allows parsing fields from messages via Extractors (for individual fields) or Processing Pipelines (for complex logic).

Pipeline for Nginx logs (System → Pipelines):

rule "parse nginx access log"
when
  has_field("source_type") AND to_string($message.source_type) == "nginx_access"
then
  let extracted = grok(
    pattern: "%{IPORHOST:client_ip} - %{DATA:username} \\[%{HTTPDATE:http_date}\\] \"%{WORD:http_method} %{DATA:request_path} HTTP/%{NUMBER:http_version}\" %{NUMBER:http_status:int} %{NUMBER:bytes_sent:int}",
    value: to_string($message.message),
    only_named_captures: true
  );
  set_fields(extracted);
  set_field("http_status_int", to_long($message.http_status));
end

rule "tag error responses"
when
  has_field("http_status_int") AND to_long($message.http_status_int) >= 500
then
  set_field("is_error", true);
  add_tag("http_error");
end

Streams — Log Routing

Streams partition the log flow by categories with different retention policies:

• All Nginx Access — source_type = nginx_access → retention 30 days
• Application Errors — level = ERROR or CRITICAL → retention 90 days
• Security Events — tags contain "security" → retention 180 days

Each stream can have its own Index Set with independent rotation settings.

Index Sets — Storage Management

System → Index Sets → Create index set:

Index prefix: app-errors
Max number of indices: 90
Index rotation: Time-based, Daily
Index retention: Delete, max 90 indices
Shards: 2
Replicas: 0 (for single-node)

Alerts

Graylog supports Event Definitions — condition-based alerts:

Alerts → Event Definitions → Create:

Title: High 5xx error rate
Condition: Aggregation
  - Stream: All Nginx Access
  - Group by: (none)
  - Count messages
  - Filter: http_status >= 500
  - Execute every: 5 minutes
  - Condition: count > 50

Notification:
  Type: HTTP Notification
  URL: https://api.telegram.org/bot<TOKEN>/sendMessage
  Body: {"chat_id": "<ID>", "text": "High error rate: ${event.message}"}

Dashboard

In Graylog, dashboards are built from search widgets. Standard set for web applications:

• Message count (all logs, 24h) — number
• HTTP status codes (Pie chart, http_status field)
• Error rate (Line chart, level:ERROR filter, group by time)
• Top request paths (Table, Top values by request_path)
• Geographic distribution (Map, if GeoIP enabled)

Timeline

Deploying Graylog + OpenSearch + MongoDB, configuring Inputs, Filebeat for Nginx, GELF logging from application, basic Pipeline rules, Index Sets with retention policy, initial alerts: 1-2 working days.