Senior Sre

We are seeking a Senior SRE - WAF/CDN Engineer to support one of our clients in building, securing, and scaling their Content Delivery Network (CDN) and Web Application Firewall (WAF) platform. This role will focus on implementing new features, optimizing performance, and strengthening security controls across the client’s edge infrastructure.

This position requires a highly technical professional capable of working autonomously while contributing to the reliability, performance, and security of a mission-critical edge platform.

**About First Factory**

We are a software development company with over two decades of experience, boasting a dynamic team of 175+ professionals actively engaged in diverse projects across various industries. We invite you to join us on this journey as we thrive and embrace fresh challenges.

**Key Responsibilities**
- Design, implement, and ship features and improvements for our CDN and WAF edge stack.
- Develop and maintain Lua code running in Nginx/OpenResty and build high-performance C modules or FFI bindings where needed.
- Implement packet
- and kernel-level observability or filtering using eBPF (including XDP/eBPF tracing for telemetry and enforcement).
- Tune and troubleshoot high-volume Nginx deployments for latency, throughput and memory usage.
- Define, author, and maintain WAF rule logic, request/response inspection and mitigation workflows.
- Build automation for deployment and configuration using Infrastructure-as-Code (Ansible, Puppet, Terraform, or similar).
- Work with networking protocols and operational requirements of a CDN: BGP, anycast, TCP/IP stack, load balancing and connection handling.
- Create and run performance/load tests, fuzzing and security tests; profile and optimize hotspots.
- Produce clear design documentation, runbooks, and hand over completed work to operations. Participate in code reviews and mentor engineers.
- Collaborate with product, security, and SRE teams to align feature work with product goals and SLAs.

**Requirements**:

- 5+ years of production experience in Linux systems engineering, networked services, or edge infrastructure.
- Strong hands-on experience with Nginx and Lua (ngx_lua/OpenResty), including writing Lua modules for request processing.
- Familiarity or experience building native C modules or FFI bindings used by Nginx/Lua; comfortable with libc, POSIX APIs and building/packaging C extensions.
- Practical experience with eBPF (tools, BCC/libbpf, XDP) for telemetry, filtering or tracing.
- Deep knowledge of networking and TCP/IP internals, load balancing, and CDN operational patterns. Familiarity with BGP and anycast is a plus.
- Solid Linux kernel and userland troubleshooting skills: perf, tcpdump/wireshark, strace, systemtap
- Experience with Infrastructure-as-Code and configuration management (Ansible, Puppet, Chef, Terraform or similar).
- Experience deploying and maintaining WAF rulesets and policies; understanding of OWASP top risks and typical web attack patterns.
- Experience with testing and benchmarking tools (wrk, ab, locust, etc.) and CI/CD pipelines.
- Excellent communication skills; able to work independently and collaborate effectively with distributed teams.

**Nice to have**
- Prior experience building or operating CDNs or edge platforms.
- Familiarity with web security tooling/modsecurity or other WAF platforms.
- Experience with container workflows and edge deployment (Docker, HashiCorp Nomad).
- Exposure to cloud providers’ networking (AWS/GCP/Azure) and hybrid edge deployments.
- Familiarity with observability stacks: Prometheus, Grafana, ELK/EFK.
- Experience cross-compiling or packaging modules for multiple Linux distributions.
- Experience programming in Lua and C, with familiarity using LuaJIT and the Lua FFI for native, high-performance integrations.