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Introduction
Logs provide valuable information about system activity, application errors, security events, and infrastructure performance. As the number of servers increases, checking logs individually becomes difficult.
Centralized log management collects logs from multiple systems into a central platform for searching, monitoring, troubleshooting, alerting, and compliance.
Two common architectures are:
1. On-Premises Logging
In an on-premises environment, Filebeat or rsyslog collects logs from Linux servers and forwards them to Logstash.
Logstash processes and filters the logs before sending them to Elasticsearch, where they are indexed and stored.
Kibana provides a centralized interface for searching logs and creating dashboards.
This architecture provides flexibility and control but requires the organization to manage the servers, storage, upgrades, security, and availability of the logging platform.
2. AWS Logging
AWS provides managed services for centralized logging.
The CloudWatch Agent collects logs from EC2 instances and sends them to CloudWatch Logs.
From there, logs can be retained in CloudWatch, archived in Amazon S3, or analyzed using Amazon OpenSearch when advanced searching and visualization are required.
The major advantage is reduced infrastructure management and easier scalability.
3. Log Retention
Log retention defines how long logs should be stored.
Retention should be based on:
- Business requirements
- Security requirements
- Compliance
- Troubleshooting needs
- Storage cost
Older logs can be archived to lower-cost storage such as S3.
4. Security
Logs may contain sensitive information such as usernames, IP addresses, authentication events, and application details.
Therefore, logging systems should use:
- Access control
- Encryption
- Secure log transmission
- Role-based permissions
- Protection against unauthorized deletion or modification
5. Troubleshooting and Alerting
Centralized logging makes troubleshooting faster by allowing teams to search logs from multiple servers in one place.
For example, an HTTP 500 error can be correlated with application, web server, and database logs to identify the root cause.
Logs can also generate alerts for events such as:
- Multiple failed SSH attempts
- HTTP 5xx errors
- Application failures
- Database connection errors
- Security events
6. Storage and Cost Management
Logs can grow rapidly in large environments. Therefore, organizations should avoid storing unnecessary logs indefinitely.
Recommended practices include:
- Define retention periods
- Collect only required logs
- Archive older logs
- Monitor storage usage
- Separate frequently accessed logs from archived logs
7. On-Premises vs AWS
Best Practices
A good centralized logging strategy should:
- Centralize logs from all critical systems
- Define clear retention policies
- Secure log data and access
- Monitor the logging pipeline
- Configure meaningful alerts
- Control storage and operational costs
- Synchronize system time for accurate event correlation
Conclusion
Centralized logging provides a single source of visibility across infrastructure.
On-premises environments commonly use:
Filebeat/rsyslog → Logstash → Elasticsearch → Kibana
while AWS environments can use:
CloudWatch Agent → CloudWatch Logs → S3/OpenSearch
Regardless of the platform, the objective remains the same:
Collect → Centralize → Analyze → Alert → Retain → Protect
A well-designed logging strategy improves troubleshooting, security, monitoring, compliance, and operational visibility.
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