Software Development Engineer (Test) 3 (UK)

In this role you will help run and grow the automated testing and test infrastructure for Sophos' Linux Behavioural Engine. You’ll maintain Buildkite CI, AWS estate, and Kubernetes clusters to keep builds and tests reliable, while also designing and implementing new test pipelines and automation. You’ll broaden coverage across Linux distributions, kernels, and container runtimes, and collaborate with senior engineers on architecture. This position offers hands-on work in automation, testing, and infrastructure with meaningful impact on security tooling at scale.

• remote-first working model
• diversity and inclusion networks
• charity and volunteering initiatives
• global sustainability initiatives
• fitness and trivia competitions
• wellbeing days/webinars

• Maintain and improve Buildkite CI pipelines, agents, queues, plugins, build performance, and reliability
• Support and monitor cloud estate and CI/automation systems (AWS, Kubernetes)
• Build new test pipelines for features/platforms with design input from senior engineers
• Write automated tests across component, integration, end-to-end, and stability levels
• Extend platform coverage across Linux distributions, kernel versions, and container runtimes
• Contribute to test tooling enabling reproducible tests and scenarios
• Investigate flaky tests and faulty infrastructure to identify root causes
• Instrument CI to monitor build health, durations, and failure patterns
• Work with infrastructure as code to automate remaining hand-built pieces
• Collaborate daily with developers and release engineering on testability and release readiness
• Share responsibility for keeping CI and test estate operational

• A few years of commercial experience in test automation, SDET, QA engineering or similar
• Proficiency in Python, Go, C++, or Rust, with willingness to learn others
• Hands-on experience with CI/CD pipelines (Buildkite, Jenkins, GitLab CI, GitHub Actions)
• Practical cloud experience, ideally AWS (IAM, compute, networking, storage)
• Familiarity with containers and Kubernetes (EKS, AKS, GKE)
• Exposure to infrastructure as code (Terraform, CloudFormation, Ansible) or interest in learning
• Comfort with Git and modern code review workflows
• Linux fundamentals: processes, filesystems, networking, systemd, permissions, packaging, troubleshooting

• Python
• Go
• C++
• Rust
• Buildkite
• Jenkins