Fastly FAQs Asked in DevOps Interviews [2025]

Core Concepts

1. What is Fastly’s primary function in DevOps?

Fastly is an edge cloud platform enhancing content delivery and compute. Its functions include accelerating web applications, enabling custom VCL logic, integrating with CI/CD pipelines, providing real-time logging, securing apps with WAF, managing TLS certificates, and scaling for global traffic. It reduces latency by 50% through edge caching, making it essential for DevOps teams focused on performance, automation, and security in modern cloud environments.

2. Why choose Fastly for edge computing?

Fastly’s edge computing executes code near users, slashing latency significantly. It supports VCL and Compute for custom logic, integrates seamlessly with DevOps tools, and handles dynamic content efficiently. By enabling real-time processing and security at the edge, Fastly empowers teams to optimize performance, scale applications, and maintain robust security without relying heavily on origin servers, making it a top choice for cloud-native workflows.

3. When should Fastly be deployed in workflows?

Deploy Fastly when:

• Needing low-latency content delivery.
• Customizing caching for apps.
• Securing traffic at edge.
• Automating via CI/CD.
• Versioning configs in Git.
• Monitoring real-time metrics.
• Scaling for global users.

Its integration with OpenShift and ability to handle traffic spikes make it ideal for high-performance applications requiring rapid updates and reliability.

4. Where does Fastly store cached content?

Fastly stores cached content in:

• Global edge POPs for accessibility.
• Shielding POPs for origin efficiency.
• Cloud regions for scalability.
• Git-versioned configurations.
• Monitored cache layers.
• Dynamic storage systems.
• API-managed nodes.

This distributed approach ensures content is served quickly, reducing origin load and improving user experience across diverse geographic regions.

5. Who manages Fastly services in teams?

DevOps engineers manage Fastly services. They:

• Configure VCL for logic.
• Optimize caching strategies.
• Integrate with pipelines.
• Monitor performance metrics.
• Track changes in Git.
• Execute cache purges.
• Troubleshoot delivery issues.

Their expertise ensures seamless content delivery, security enforcement, and scalability, aligning Fastly with organizational goals for efficient application performance.

6. Which feature enhances content delivery speed?

Edge caching enhances delivery speed, offering:

• High cache hit ratios.
• Granular purge with keys.
• VCL integration for control.
• Git-versioned policies.
• Monitored hit rates.
• Scalable traffic handling.
• Dynamic TTL adjustments.

This feature minimizes latency, optimizes resource use, and ensures fast content delivery for global users, critical for high-traffic applications.

7. How does Fastly manage dynamic content?

Fastly manages dynamic content by:

• Using VCL for custom routing.
• Shielding origins for efficiency.
• Leveraging Compute for logic.
• Versioning rules in Git.
• Monitoring response times.
• Scaling for request volume.
• Reducing origin load.

For instance, VCL can route API requests to specific backends, ensuring low latency and seamless integration with platforms like Kubernetes.

VCL Customization

8. What is VCL in Fastly’s ecosystem?

VCL (Varnish Configuration Language) is Fastly’s tool for customizing edge behavior. It enables:

• Defining caching policies.
• Routing requests dynamically.
• Integrating with Compute.
• Versioning logic in Git.
• Monitoring script execution.
• Scaling for complex rules.
• Debugging with logs.

VCL empowers developers to tailor content delivery, security, and routing, ensuring flexibility and performance in DevOps workflows.

9. Why use VCL for caching control?

VCL provides granular control over caching, boosting hit rates by 30%. It allows custom headers, TTL settings, and dynamic rules, integrating with CI/CD for automation. By reducing origin requests, VCL enhances performance and scalability, making it indispensable for teams managing high-traffic applications with specific caching needs in modern cloud environments.

10. When should custom VCL be implemented?

Implement custom VCL when:

• Requiring specific routing logic.
• Customizing cache durations.
• Enforcing edge security.
• Integrating with external APIs.
• Tracking changes in Git.
• Monitoring rule performance.
• Resolving unique scenarios.

This approach ensures tailored content delivery, aligning with application requirements and DevOps practices for efficient management.

11. Where are VCL configurations stored?

VCL configurations are stored in:

• Fastly service settings.
• Git repositories for versioning.
• CI/CD pipeline scripts.
• Monitored service dashboards.
• Configuration management tools.
• API-accessible endpoints.
• Backup storage systems.

This centralized storage facilitates collaboration, version control, and automated deployments, ensuring consistency across environments.

12. Who writes VCL scripts for Fastly?

Edge engineers write VCL scripts. They:

• Design routing logic.
• Test in staging environments.
• Integrate with CI/CD pipelines.
• Monitor script performance.
• Version scripts in Git.
• Optimize caching rules.
• Handle error debugging.

Their expertise ensures customized edge behavior, aligning with performance and security goals in DevOps workflows.

13. Which VCL subroutine handles incoming requests?

The vcl_recv subroutine handles incoming requests, offering:

• Header manipulation capabilities.
• Backend selection logic.
• Integration with security rules.
• Git-versioned configurations.
• Monitored request processing.
• Scalable traffic handling.
• Conditional routing options.

This subroutine is critical for controlling how Fastly processes client requests, ensuring efficient and secure delivery.

14. How do you purge cache using VCL?

Purge cache in VCL by:

• Issuing API purge calls.
• Using surrogate keys.
• Opting for soft purges.
• Testing in staging environments.
• Versioning in Git.
• Monitoring purge status.
• Handling purge errors.

This process refreshes content efficiently, ensuring users receive updated data without overloading origins, as seen in GCP workflows.

15. What are common VCL configuration errors?

Common VCL errors include syntax mistakes and logic loops, leading to redirects or cache misses. Incorrect subroutine configurations disrupt traffic flow. To mitigate, engineers test scripts in staging, use debugging headers, and monitor performance. Integration with platforms like GCP ensures validation before deployment, reducing errors in production environments.

Caching Strategies

16. What is edge caching in Fastly?

Edge caching stores content at Fastly’s POPs, reducing latency. It involves:

• Surrogate keys for purges.
• Custom TTL configurations.
• VCL for dynamic rules.
• Git for version control.
• Monitoring cache metrics.
• Scaling for traffic spikes.
• Shielding for origin relief.

This mechanism accelerates content delivery, enhancing user experience across global regions.

17. Why configure custom TTLs in Fastly?

Custom TTLs optimize caching by balancing freshness and performance, improving hit rates significantly. They allow fine-tuned control for static and dynamic content, integrate with VCL for flexibility, and support DevOps automation. By reducing origin requests, TTLs enhance scalability and user satisfaction, making them critical for high-performance applications in cloud-native environments.

18. When should surrogate keys be used?

Use surrogate keys when:

• Needing granular cache purges.
• Managing related content groups.
• Integrating with external APIs.
• Versioning in Git repositories.
• Monitoring purge efficiency.
• Scaling for large catalogs.
• Troubleshooting cache issues.

Surrogate keys enable precise cache management, ensuring efficient updates and minimal origin load.

19. Where are caching rules defined?

Caching rules are defined in:

• VCL scripts for logic.
• Fastly UI configurations.
• Git repositories for versioning.
• CI/CD pipeline settings.
• Monitored service dashboards.
• API-driven endpoints.
• External configuration tools.

This structured storage ensures rules are accessible, maintainable, and aligned with DevOps practices.

20. Who optimizes caching strategies?

Performance engineers optimize caching. They:

• Adjust TTL and keys.
• Analyze hit rate metrics.
• Test rules in staging.
• Integrate with VCL scripts.
• Version policies in Git.
• Execute timely purges.
• Monitor traffic patterns.

Their work maximizes cache efficiency, reducing latency and enhancing application performance.

21. Which header controls cache behavior?

The Cache-Control header controls behavior, offering:

• Max-age for TTL settings.
• No-cache for validation.
• VCL integration for rules.
• Git for version tracking.
• Monitored compliance checks.
• Scalable response handling.
• Custom directive support.

This header ensures content freshness and efficient delivery, critical for user experience.

22. How do you enhance cache hit ratios?

Enhance cache hit ratios by:

• Using surrogate keys effectively.
• Setting optimal TTL values.
• Enabling origin shielding.
• Testing in staging environments.
• Versioning in Git.
• Monitoring hit metrics.
• Optimizing VCL logic.

These steps reduce origin load, improve performance, and ensure scalability, as seen in cloud environments.

23. What are the steps to set up caching?

Setting up caching involves defining TTLs, surrogate keys, and VCL rules to optimize performance. Engineers configure policies in Fastly’s UI or API, test in staging, and monitor hit rates. Versioning in Git ensures traceability, while integration with CI/CD automates updates, aligning with DevOps practices for efficient content delivery across global networks.

Security and WAF

24. What is Fastly’s WAF solution?

Fastly’s WAF protects applications at the edge. It provides:

• OWASP Top 10 rule sets.
• Custom VCL-based rules.
• Real-time threat alerts.
• Git for rule versioning.
• Monitored attack detection.
• Scalable traffic handling.
• Rate-limiting capabilities.

This solution blocks threats like SQL injection, ensuring robust security for web applications.

25. Why deploy WAF at the edge?

Deploying WAF at the edge mitigates threats before they reach origins, reducing attack surfaces significantly. It integrates with VCL for custom rules, supports real-time monitoring, and aligns with DevSecOps practices. By blocking malicious traffic early, it enhances security, improves performance, and ensures compliance, making it essential for protecting modern applications.

26. When to customize WAF rules?

Customize WAF rules when:

• Addressing specific vulnerabilities.
• Minimizing false positives.
• Integrating with VCL logic.
• Versioning in Git repositories.
• Monitoring rule effectiveness.
• Scaling for traffic volume.
• Troubleshooting blocked requests.

27. Where are WAF logs stored?

WAF logs are stored in:

• Real-time streaming endpoints.
• Cloud storage buckets.
• Git-versioned configurations.
• SIEM systems for analysis.
• Monitored dashboards.
• API-accessible logs.
• External logging tools.

This storage enables rapid threat analysis, compliance tracking, and integration with observability platforms for proactive security management.

28. Who configures WAF settings?

Security engineers configure WAF settings. They:

• Define rule priorities.
• Test rules in staging.
• Integrate with VCL scripts.
• Monitor threat alerts.
• Version rules in Git.
• Handle false positives.
• Optimize rule performance.

Their expertise ensures robust protection, aligning with DevSecOps goals for secure application delivery.

29. Which rule set protects against XSS?

The OWASP Core Rule Set protects against XSS, offering:

• Pattern-based detection.
• VCL integration for flexibility.
• Git for rule versioning.
• Monitored attack detection.
• Scalable traffic handling.
• Custom rule adjustments.
• Reduced false positives.

This set safeguards applications, ensuring secure content delivery across diverse environments.

30. How do you implement rate limiting?

Implement rate limiting by:

• Using VCL for IP counters.
• Setting request thresholds.
• Testing limits in staging.
• Versioning in Git.
• Monitoring rate metrics.
• Handling traffic bursts.
• Integrating with WAF.

This prevents abuse, protects resources, and ensures stable performance, as practiced in cloud-native setups.

31. What are the steps to enable TLS?

Enabling TLS secures traffic across Fastly’s network. Engineers upload certificates, configure SNI, test HTTPS connections, and monitor metrics. Versioning in Git ensures traceability, while integration with WAF enhances security. This process guarantees encrypted delivery, protects user data, and aligns with compliance requirements for modern web applications.

32. Why does WAF block legitimate traffic?

WAF blocks legitimate traffic due to overly strict rules or pattern mismatches. False positives from broad configurations disrupt users. Engineers tune rules, whitelist IPs, and monitor alerts to resolve issues. Integration with platforms like GCP provides real-time insights, ensuring minimal disruption and effective security management.

Origin and Backend Management

33. What defines a backend in Fastly?

A backend is the origin server fetching content. It includes:

• Host and port configurations.
• Health check endpoints.
• Shielding for efficiency.
• Git for versioning configs.
• Monitored backend status.
• Scalable load balancing.
• Secure connection options.

Backends ensure reliable content retrieval, supporting high-traffic applications with minimal latency.

34. Why use multiple backends?

Multiple backends provide redundancy, ensuring 99.9% uptime. They enable failover, balance load, and integrate with VCL for dynamic routing. This setup supports scalability, reduces single-point failures, and aligns with DevOps practices for resilient application delivery across global regions, enhancing performance and reliability.

35. When to configure backend health checks?

Configure health checks when:

• Ensuring origin availability.
• Routing to healthy servers.
• Integrating with VCL logic.
• Versioning in Git.
• Monitoring server health.
• Scaling for traffic surges.
• Troubleshooting downtimes.

Health checks maintain uptime, ensuring seamless content delivery, as seen in cloud deployments.

36. Where are backend configurations stored?

Backend configurations are stored in:

• Fastly UI or API endpoints.
• Git repositories for versioning.
• CI/CD pipeline scripts.
• Monitored service dashboards.
• Configuration management tools.
• External backup systems.
• API-driven storage.

This ensures accessibility, collaboration, and automated management for consistent operations.

37. Who manages backend settings?

DevOps teams manage backend settings. They:

• Configure host/port details.
• Implement health checks.
• Integrate with VCL rules.
• Monitor backend status.
• Version configs in Git.
• Handle failover scenarios.
• Optimize load distribution.

Their work ensures reliable content delivery and scalability for high-performance applications.

38. Which protocol secures backend connections?

HTTPS secures backend connections, offering:

• End-to-end encryption.
• VCL integration for logic.
• Git for config versioning.
• Monitored connection metrics.
• Scalable traffic handling.
• Custom cipher support.
• WAF integration.

This protocol protects data in transit, ensuring secure and compliant content delivery.

39. How do you route traffic to backends?

Route traffic to backends by:

• Using VCL conditionals.
• Setting backend variables.
• Testing routes in staging.
• Versioning in Git.
• Monitoring traffic flow.
• Handling routing errors.
• Scaling for load.

This approach ensures dynamic, efficient routing, as practiced in cloud workflows.

40. What are the steps to add a backend?

Adding a backend expands content sources. Engineers define host/port, configure health checks, test connectivity, and update VCL for routing. Monitoring backend status and versioning in Git ensure reliability. This process supports scalable, resilient delivery, aligning with DevOps practices for global application performance and uptime.

41. Why does backend failover fail?

Backend failover fails due to misconfigured health checks or VCL logic errors. Unreachable servers or incorrect thresholds cause disruptions. Engineers adjust intervals, validate configurations, and monitor health metrics. Integration with platforms like Azure provides real-time insights, ensuring reliable failover and minimal downtime in production.

Monitoring and Logging

42. What is real-time logging in Fastly?

Real-time logging streams request and response data instantly. It includes:

• Detailed event tracking.
• Integration with SIEM tools.
• Git for log configurations.
• Monitored stream health.
• Scalable log volumes.
• Custom log formats.
• Debugging capabilities.

This feature provides immediate visibility, enabling rapid issue detection and resolution.

43. Why enable real-time logging?

Real-time logging detects issues instantly, reducing mean time to resolution by 50%. It integrates with observability tools, supports compliance requirements, and scales for high-traffic applications. By providing detailed insights into requests, it empowers DevOps teams to troubleshoot performance, security, and delivery issues efficiently in cloud-native environments.

44. When to use log streaming?

Use log streaming when:

• Analyzing live traffic patterns.
• Integrating with SIEM systems.
• Monitoring security incidents.
• Versioning configs in Git.
• Scaling for log volume.
• Troubleshooting real-time issues.
• Ensuring compliance audits.

Streaming enables proactive monitoring, as seen in observability practices.

45. Where are logs streamed?

Logs are streamed to:

• Cloud storage buckets.
• SIEM systems for analysis.
• Grafana Loki for visualization.
• Git-versioned configurations.
• Monitored log endpoints.
• API-driven log sinks.
• External processing tools.

This ensures logs are accessible for analysis, compliance, and troubleshooting across platforms.

46. Who configures log streaming?

Observability engineers configure streaming. They:

• Define streaming endpoints.
• Specify log formats.
• Test streams in staging.
• Integrate with observability tools.
• Version configs in Git.
• Monitor stream health.
• Manage log quotas.

Their work ensures actionable insights, supporting performance and security monitoring in DevOps.

47. Which log format is optimal?

JSON is the optimal log format, offering:

• Structured data parsing.
• SIEM tool integration.
• Git for config versioning.
• Monitored log fields.
• Scalable log processing.
• Custom field support.
• Accurate timestamps.

JSON enables efficient log analysis, ensuring compatibility with modern observability platforms.

48. How do you monitor Fastly performance?

Monitor performance by:

• Using Fastly Insights.
• Integrating with Grafana.
• Setting latency alerts.
• Testing metrics in staging.
• Versioning in Git.
• Tracking cache hits.
• Scaling monitoring tools.

This approach provides real-time visibility, ensuring optimal performance and quick issue resolution, as seen in cloud monitoring.

49. What are the steps to integrate with Grafana?

Integrating with Grafana visualizes Fastly metrics for observability. Engineers generate API tokens, configure data sources, query metrics like cache hits, and build dashboards. Alerts are set for anomalies, and configurations are versioned in Git. This setup ensures real-time performance tracking, aligning with DevOps practices for proactive monitoring and issue resolution.

50. Why do logs stop streaming?

Log streaming stops due to endpoint misconfigurations, quota limits, or network issues. Incorrect formats or authentication errors disrupt flow. Engineers verify endpoints, adjust quotas, and monitor streams to resolve issues. Integration with platforms like Azure provides insights, ensuring reliable logging and compliance in production environments.

Edge Compute and APIs

51. What is Fastly Compute?

Fastly Compute runs WebAssembly at the edge. It supports:

• AssemblyScript for coding.
• VCL for hybrid logic.
• Git for code versioning.
• Monitored function execution.
• Scalable compute resources.
• Dynamic request handling.
• Serverless app deployment.

Compute enables low-latency, custom applications, enhancing Fastly’s flexibility for DevOps teams.

52. Why use Compute for edge functions?

Fastly Compute executes code at the edge, reducing latency for dynamic content. It supports serverless workflows, integrates with CI/CD, and scales without infrastructure management. By enabling custom logic like personalization, it enhances user experience, aligns with DevOps automation, and supports modern application requirements for performance and scalability.

53. When to deploy Compute functions?

Deploy Compute functions when:

• Running custom edge logic.
• Processing high-performance tasks.
• Integrating with external APIs.
• Versioning code in Git.
• Monitoring function runtime.
• Scaling for user traffic.
• Troubleshooting edge apps.

This extends Fastly’s capabilities, supporting complex applications, as seen in serverless architectures.

54. Where are Compute functions deployed?

Compute functions are deployed in:

• Fastly’s edge network.
• Git repositories for code.
• CI/CD pipeline builds.
• Monitored service environments.
• Versioned WASM packages.
• API-managed endpoints.
• External build systems.

This ensures seamless execution, scalability, and integration with DevOps workflows for edge applications.

55. Who develops Compute functions?

Edge developers develop Compute functions. They:

• Write AssemblyScript code.
• Test functions locally.
• Integrate with VCL logic.
• Monitor runtime metrics.
• Version code in Git.
• Manage deployments.
• Optimize performance.

Their expertise enables custom edge applications, enhancing Fastly’s flexibility for modern DevOps needs.

56. Which language supports Fastly Compute?

AssemblyScript supports Compute, offering:

• WebAssembly compilation.
• TypeScript-like syntax.
• SDK for integration.
• Git for code versioning.
• Monitored execution metrics.
• Scalable function handling.
• Debugging capabilities.

This language enables efficient, serverless edge computing, aligning with DevOps automation goals.

57. How do you deploy Compute functions?

Deploy Compute functions by:

• Using Fastly CLI tools.
• Compiling code to WASM.
• Uploading via API calls.
• Testing in staging environments.
• Versioning in Git.
• Monitoring deployment status.
• Handling rollback scenarios.

This process ensures reliable edge function deployment, as practiced in cloud pipelines.

58. What are the steps to use Fastly API?

Using Fastly API automates service management. Engineers generate tokens, script REST calls, test endpoints, and integrate with CI/CD. Configurations are versioned in Git, and usage is monitored for efficiency. This approach enables programmatic control, streamlines operations, and aligns with DevOps practices for scalable, automated content delivery systems.

59. Why do Compute functions fail to deploy?

Compute function deployments fail due to syntax errors, resource limits, or compilation issues in AssemblyScript. Incorrect configurations disrupt execution. Developers debug using logs, optimize code, and version changes in Git. Monitoring deployment metrics and testing in staging, as seen in cloud workflows, ensures successful deployments and reliable edge applications.

Performance Optimization

60. What is origin shielding in Fastly?

Origin shielding routes traffic through a single POP, reducing origin load. It includes:

• Improved cache hit rates.
• Reduced origin requests.
• VCL for routing logic.
• Git for config versioning.
• Monitored latency metrics.
• Scalable traffic handling.
• Health check integration.

Shielding enhances efficiency, ensuring faster content delivery and origin protection.

61. Why optimize image delivery?

Optimizing image delivery cuts bandwidth usage by 40%, speeding up page loads. Fastly’s image optimizer resizes, compresses, and formats images dynamically, supporting responsive designs. Integration with DevOps pipelines ensures automated delivery, while monitoring performance metrics aligns with modern application needs for fast, scalable, and user-friendly experiences across devices.

62. When to enable image optimization?

Enable image optimization when:

• Delivering responsive images.
• Reducing bandwidth usage.
• Integrating with external APIs.
• Versioning configs in Git.
• Monitoring image performance.
• Scaling for device variety.
• Troubleshooting format issues.

This enhances user experience and reduces latency, as seen in web performance.

63. Where are optimized images cached?

Optimized images are cached in:

• Fastly edge servers.
• Origin servers for originals.
• Git-versioned configurations.
• CDN caching layers.
• Monitored cache endpoints.
• Dynamic storage systems.
• Backup repositories.

This caching strategy ensures rapid delivery, scalability, and alignment with DevOps workflows.

64. Who configures image optimization?

Frontend engineers configure image optimization. They:

• Set resizing parameters.
• Test image formats.
• Integrate with VCL rules.
• Monitor delivery metrics.
• Version configs in Git.
• Handle device variants.
• Optimize for performance.

Their work ensures responsive, efficient image delivery, enhancing user experience across platforms.

65. Which format is best for images?

WebP is the best image format, offering:

• Superior compression efficiency.
• Transparency and animation support.
• Integration with Fastly optimizer.
• Git for config versioning.
• Monitored size metrics.
• Scalable web delivery.
• Browser fallback options.

WebP reduces bandwidth, ensuring fast, high-quality image delivery for modern applications.

66. How do you configure compression?

Configure compression by:

• Enabling gzip or brotli.
• Setting VCL compression rules.
• Testing in staging environments.
• Versioning in Git.
• Monitoring payload sizes.
• Handling content types.
• Optimizing for delivery.

Compression minimizes data transfer, improving load times and performance, as seen in cloud optimization.

67. What are the steps to optimize static assets?

Optimizing static assets enhances performance. Engineers enable compression, set long TTLs, use surrogate keys, and test in staging. Monitoring hit rates and versioning in Git ensure efficiency. This process reduces latency, aligns with DevOps practices, and supports scalable delivery for high-traffic applications across global networks.

68. Why do assets load slowly?

Slow asset loading results from large file sizes, poor caching, or missing compression. Unoptimized images or misconfigured TTLs cause delays. Engineers implement compression, adjust caching policies, and monitor performance metrics. Integration with platforms like Azure provides insights, ensuring faster delivery and improved user experience.

CI/CD Integration

69. What is Fastly’s Terraform provider?

Fastly’s Terraform provider automates infrastructure management. It supports:

• HCL for service resources.
• CI/CD pipeline integration.
• Git for config versioning.
• Monitored apply operations.
• Scalable infrastructure configs.
• State management tools.
• Custom data sources.

This provider enables infrastructure as code, streamlining deployments and ensuring consistency in DevOps environments.

70. Why integrate Fastly with CI/CD?

Integrating Fastly with CI/CD automates VCL updates, purges, and service configurations, reducing errors by 30%. It supports version control, real-time monitoring, and scalable deployments. This integration aligns with DevOps practices, ensuring consistent, rapid updates and reliable content delivery for high-performance applications in cloud-native ecosystems.

71. When to use Fastly CLI in pipelines?

Use Fastly CLI in pipelines when:

• Automating VCL deployments.
• Executing cache purges.
• Testing service configurations.
• Integrating with CI/CD tools.
• Versioning in Git.
• Monitoring CLI commands.
• Managing authentication tokens.

CLI streamlines automation, ensuring efficient edge management, as seen in CI/CD workflows.

72. Where are CI/CD configurations stored?

CI/CD configurations are stored in:

• Git repositories for scripts.
• Pipeline YAML files.
• Monitored service dashboards.
• External secret vaults.
• Versioned branch systems.
• Artifact storage platforms.
• Backup repositories.

This storage ensures traceability, collaboration, and automated deployments across DevOps environments.

73. Who sets up Fastly in CI/CD?

DevOps engineers set up Fastly in CI/CD. They:

• Configure CLI authentication.
• Define pipeline workflows.
• Test deployment scripts.
• Integrate with Terraform.
• Version configs in Git.
• Monitor build status.
• Handle pipeline failures.

Their work ensures automated, reliable edge configurations for scalable content delivery.

74. Which tool integrates with Fastly for CI/CD?

GitHub Actions integrates with Fastly, offering:

• Automated workflow execution.
• Fastly CLI command support.
• API integration for configs.
• Git for versioning pipelines.
• Monitored job status.
• Scalable pipeline execution.
• Error alerting mechanisms.

This tool streamlines deployments, ensuring efficient automation in DevOps environments.

75. How do you automate VCL deployments?

Automate VCL deployments by:

• Using Fastly CLI commands.
• Validating script syntax.
• Testing in staging environments.
• Versioning in Git.
• Monitoring deployment status.
• Handling rollback scenarios.
• Integrating with CI/CD tools.

Automation ensures consistent, error-free updates, aligning with modern DevOps practices, as seen in automation workflows.

76. What are the steps to integrate with Jenkins?

Integrating with Jenkins automates Fastly deployments. Engineers install Fastly CLI, configure tokens in credentials, script deployment steps, and test in staging. Monitoring build logs and versioning in Git ensure reliability. This setup streamlines edge updates, supports scalable CI/CD pipelines, and aligns with DevOps goals for consistent application delivery.

77. Why do CI/CD deployments fail?

CI/CD deployments fail due to invalid tokens, VCL syntax errors, or pipeline misconfigurations. Incorrect API calls or resource limits cause issues. Engineers validate scripts, monitor build logs, and version changes in Git. Integration with platforms like Azure provides insights, ensuring successful deployments and minimal disruptions.

Advanced Scenarios

78. What do you do for low cache hit rates?

For low cache hit rates, optimize caching strategies. Steps include:

• Analyze hit ratio metrics.
• Adjust TTL configurations.
• Test VCL rules in staging.
• Version changes in Git.
• Monitor performance improvements.
• Enable origin shielding.
• Handle dynamic content.

This approach boosts efficiency, reduces origin load, and enhances user experience across applications.

79. Why does Fastly return 502 errors?

502 errors occur due to origin failures or VCL misconfigurations. Unhealthy backends, incorrect health checks, or routing logic issues cause disruptions. Engineers verify backend status, review logs, and adjust VCL. Monitoring in platforms like Azure ensures quick resolution, restoring service and maintaining uptime for users.

80. When to purge cache in Fastly?

Purge cache when:

• Updating outdated content.
• Fixing display errors.
• Testing new content versions.
• Integrating with CI/CD pipelines.
• Versioning in Git.
• Monitoring purge status.
• Managing surrogate keys.

Purging ensures fresh content delivery, aligning with application update cycles and user expectations.

81. Where do you troubleshoot Fastly errors?

Troubleshoot errors in:

• Real-time log streams.
• Fastly UI dashboards.
• Git-versioned configurations.
• SIEM systems for analysis.
• Monitored API endpoints.
• External observability tools.
• Log aggregation platforms.

These sources provide insights, enabling rapid issue identification and resolution in production.

82. Who handles Fastly incidents?

SREs handle Fastly incidents. They:

• Analyze real-time logs.
• Review service configurations.
• Test fixes in staging.
• Integrate with CI/CD.
• Version changes in Git.
• Monitor recovery metrics.
• Document incident resolutions.

Their expertise ensures quick restoration, minimizing downtime and maintaining service reliability, as seen in SRE practices.

83. Which feature aids incident response?

Real-time logging aids incident response, offering:

• Instant event streaming.
• SIEM tool integration.
• Git for log versioning.
• Monitored alert systems.
• Scalable log processing.
• Filtered log fields.
• Debugging capabilities.

This feature accelerates triage, ensuring rapid issue resolution and service continuity.

84. How do you handle a latency spike?

Handle latency spikes by:

• Checking origin health status.
• Reviewing VCL routing logic.
• Testing fixes in staging.
• Versioning in Git.
• Monitoring latency metrics.
• Scaling edge capacity.
• Optimizing backend routes.

This approach restores performance, ensuring low-latency delivery for users, as practiced in cloud operations.

85. What are the steps to recover from purge errors?

Recovering from purge errors ensures content freshness. Engineers check purge status via API, validate surrogate keys, retry purges, and monitor cache hits. Versioning in Git tracks changes, while testing in staging prevents recurrence. This process restores reliable delivery, aligning with DevOps goals for consistent, scalable content updates across global networks.

86. Why do VCL updates cause disruptions?

VCL updates cause disruptions due to syntax errors, logic conflicts, or untested changes. Incorrect subroutines lead to routing issues or cache misses. Engineers validate scripts in staging, monitor performance, and version changes in Git. Integration with platforms like Azure provides real-time insights, preventing production issues and ensuring stable deployments.

Real-World Scenarios

87. What do you do in a multi-region deployment?

In multi-region deployments, optimize traffic routing. Steps include:

• Configuring regional backends.
• Testing latency across POPs.
• Using VCL for routing logic.
• Versioning configs in Git.
• Monitoring regional metrics.
• Enabling origin shielding.
• Scaling edge nodes.

This ensures low-latency, reliable delivery across global regions, supporting high-traffic applications.

88. Why use Fastly for A/B testing?

Fastly enables A/B testing by splitting traffic at the edge, reducing latency. It integrates with VCL for dynamic routing, supports analytics for conversion tracking, and scales for large user bases. This setup allows teams to experiment with variants, optimize user experience, and make data-driven decisions, aligning with DevOps goals for agile development and deployment.

89. When to implement geo-routing?

Implement geo-routing when:

• Targeting region-specific users.
• Minimizing content latency.
• Integrating with VCL rules.
• Versioning in Git.
• Monitoring routing performance.
• Scaling for global traffic.
• Troubleshooting misrouting issues.

Geo-routing optimizes delivery, ensuring fast, localized content access, as seen in cloud architectures.

90. Where are geo-routing configurations stored?

Geo-routing configurations are stored in:

• VCL scripts for logic.
• Git repositories for versioning.
• CI/CD pipeline scripts.
• Monitored service dashboards.
• API-driven endpoints.
• External configuration tools.
• Backup storage systems.

This storage ensures traceability, collaboration, and automated management for consistent routing.

91. Who configures geo-routing in Fastly?

Network engineers configure geo-routing. They:

• Define region-specific rules.
• Test routing in staging.
• Integrate with VCL logic.
• Monitor traffic distribution.
• Version configs in Git.
• Handle latency issues.
• Optimize routing paths.

Their expertise ensures efficient, localized content delivery, aligning with performance goals.

92. Which VCL variable enables geo-routing?

The client.geo variable enables geo-routing, offering:

• Region and country data.
• VCL integration for logic.
• Git for config versioning.
• Monitored routing metrics.
• Scalable traffic handling.
• Custom routing logic.
• Dynamic path selection.

This variable ensures targeted, low-latency delivery for global users, enhancing performance.

93. How do you set up A/B testing?

Set up A/B testing by:

• Defining traffic splits in VCL.
• Setting variant ratios.
• Testing splits in staging.
• Versioning in Git.
• Monitoring conversion metrics.
• Integrating with analytics.
• Managing variant traffic.

This enables experimentation, supporting data-driven decisions, as seen in application testing.

94. What are the steps for multi-region failover?

Configuring multi-region failover ensures uptime. Engineers add regional backends, set health checks, test failover scenarios, and monitor latency. VCL rules are updated for routing, and configurations are versioned in Git. This process guarantees resilient content delivery, minimizing disruptions and aligning with DevOps practices for scalable, global application performance.

95. Why does geo-routing fail?

Geo-routing fails due to outdated geo-data, VCL errors, or misconfigured rules. Incorrect logic leads to misrouting, impacting performance. Engineers validate configurations, test in staging, and monitor metrics. Integration with platforms like Azure provides insights, ensuring accurate routing and minimal latency for users.

96. What is Fastly API’s role in automation?

Fastly API automates service management. It enables:

• RESTful service configurations.
• Programmatic cache purges.
• CI/CD pipeline integration.
• Git for versioning scripts.
• Monitored API usage.
• Scalable automation tasks.
• Token-based authentication.

The API streamlines operations, reducing manual effort and ensuring consistent, scalable content delivery.

97. Why use Fastly CLI for automation?

Fastly CLI automates VCL and service management, cutting manual effort by 30%. It integrates with CI/CD, supports version control, and enables rapid updates. By streamlining deployments and purges, CLI ensures consistency and scalability, aligning with DevOps practices for efficient edge management in high-traffic applications, as seen in automation practices.

98. When to use API over CLI?

Use API over CLI when:

• Scripting complex automation tasks.
• Integrating with external tools.
• Handling bulk configuration updates.
• Versioning scripts in Git.
• Monitoring API call metrics.
• Scaling for large operations.
• Troubleshooting endpoint issues.

API offers greater flexibility, supporting advanced automation scenarios in DevOps workflows.

99. Where are API automation scripts stored?

API automation scripts are stored in:

• Git repositories for versioning.
• CI/CD pipeline configurations.
• Monitored service dashboards.
• External secret management tools.
• Versioned script libraries.
• Artifact storage systems.
• Backup repositories.

This storage ensures secure, accessible, and traceable automation for Fastly operations.

100. Who writes API automation scripts?

Automation engineers write API scripts. They:

• Develop RESTful automation code.
• Test endpoints in staging.
• Integrate with CI/CD pipelines.
• Monitor call performance.
• Version scripts in Git.
• Handle API errors.
• Optimize call efficiency.

Their work automates Fastly management, ensuring scalable, reliable operations in DevOps environments.

101. Which authentication secures Fastly API?

Token-based authentication secures Fastly API, offering:

• Header-based access control.
• CI/CD integration for automation.
• Git for token versioning.
• Monitored access metrics.
• Scalable call handling.
• Revocation for security.
• Scoped permissions.

This method ensures secure, controlled access, protecting API endpoints, as seen in security practices.

102. How do you manage API rate limits?

Manage API rate limits by:

• Monitoring call usage metrics.
• Implementing retry mechanisms.
• Testing limits in staging.
• Versioning scripts in Git.
• Optimizing API calls.
• Handling quota errors.
• Integrating with CI/CD.

This ensures compliance, prevents disruptions, and supports scalable automation in DevOps workflows.

103. What are the steps to troubleshoot a 503 error?

Troubleshooting 503 errors restores service reliability. Engineers verify origin health, check real-time logs, test VCL rules, and monitor backend status. Configurations are versioned in Git to track changes. Adjusting health checks and optimizing routing resolve issues. This process ensures minimal downtime, aligning with DevOps goals for resilient, scalable content delivery, as seen in troubleshooting practices.