An overview of Cloudflare's logging pipeline

As a rapidly growing company, it was important for Cloudflare to develop a robust and scalable logging pipeline. This pipeline is essential for monitoring network performance, troubleshooting issues, and analyzing security threats. The company's logging infrastructure needed to be able to handle large volumes of data from various sources, while also being resilient to failures. The logging pipeline starts with syslog-ng, a secure log management tool that runs on each machine within the Cloudflare network. Syslog-ng is configured to send logs to two different locations: one in the United States and another in Europe. This redundancy helps ensure that no data is lost due to failures at any single point. Once the logs reach these core data centers, they are buffered in a Kafka queue. Kafka provides several benefits, including allowing consumers of the logs to be easily added or removed without affecting other parts of the system. Additionally, it allows Cloudflare to tolerate transient failures of its log consumers without losing any data. After being stored in Kafka, the logs are then inserted into long-term storage systems: ElasticSearch/Logstash/Kibana (ELK) and Clickhouse clusters. The ELK stack is a powerful search engine that enables engineers to quickly find relevant information within large datasets. Clickhouse, on the other hand, provides an SQL interface for querying log data. In order to continue meeting the demands of Cloudflare's growth, there are several ongoing projects aimed at improving and scaling the logging pipeline. These include increasing multi-tenancy capabilities, moving towards Open Telemetry, implementing tail sampling instead of head sampling, and optimizing Kafka balancing. Overall, Cloudflare's logging infrastructure plays a crucial role in maintaining network performance and security across its global network. By continuously investing in this system, the company can ensure that it remains resilient, scalable, and effective for years to come.