CloudFront Access Logs Overview

• Purpose: CloudFront access logs capture every request made to your origin through CloudFront, logging details into a designated S3 bucket.
• Operation: Users access your site via a CloudFront URL. Each edge location sends its log files to a central S3 bucket specified for logging.
• Bucket Types: There are two distinct S3 bucket types involved:
  • Origin Bucket: Linked to CloudFront for content hosting.
  • Logs Bucket: Receives log files for access analysis.

Setting Up Access Logs

1. Enable Logging: Through the CloudFront distribution's settings, you can turn on standard logging, specifying an S3 bucket for the logs.
2. Log Prefix: Optionally, add a prefix to organize logs within the S3 bucket, especially useful if managing logs from multiple distributions.

Analyzing Access Logs

• Content: Logs include detailed request information, such as date, time, request type, status codes, and more.
• Tools for Analysis: AWS Athena can be used to analyze the log files for insights into access patterns and issues.

CloudFront Reports and Analytics

• Reports Generated from Access Logs: CloudFront offers several reports without needing access logs to be enabled in S3, including Cache Statistics, Popular Objects, Top Referrers, Usage, and Viewers Reports.
• Cache Performance: Insights into cache hits and misses, indicating the efficiency of content delivery.
• Data Transfer and HTTP Status Codes: Analysis of bytes transferred, cache performance, and encountered HTTP status codes.
• Viewer Insights: Information on referrers, viewer devices, browsers, operating systems, and geographic locations accessing the distribution.

Monitoring and Troubleshooting

• Error Caching: CloudFront caches HTTP 400 and 500 series errors from S3 or the origin server, with specific codes indicating access issues or non-existent objects.
• Monitoring Tools: CloudFront integrates with AWS monitoring tools to track requests, data transfers, error rates, origin latency, and cache error rates over time.

Key Takeaways

• Logs and Analytics Integration: CloudFront's logging and reporting capabilities provide comprehensive insights into distribution performance and viewer behavior.