Principal Software Engineer, AWS Lambda

Are you passionate about building the foundational systems that power serverless computing for millions of customers worldwide? AWS Lambda is looking for a Principal Engineer to join our Lambda Experience team in Dublin, Ireland, where you will define the technical vision and drive the architecture for the Lambda execution environment, the system that execute customer code across the globe. AWS Lambda is one of the fastest-growing services in AWS and sits at the heart of serverless computing. The Lambda execution environment is responsible for securely launching and managing the compute environment where customer code runs. This includes the orchestration of microVM-based isolation using Firecracker, the management of execution environments, and the runtime interfaces that bridge customer code with the Lambda platform. The systems you will work on process millions of invocations per second, operate across multiple AWS Regions, and must deliver consistently low latency while maintaining the highest standards of security and isolation. As a Principal Engineer on this team, you will own the long-term technical strategy for the Lambda execution environment, working at the intersection of systems programming, virtualization, and cloud infrastructure. You will design and build the next generation of execution environment management, tackle challenges in cold start optimization, resource scheduling, and multi-tenant isolation, and drive the evolution of our Rust and Linux kernel-level components so that, among other things, they are ready to carry our customers’ next generation workloads, including agentic ones. You will operate as both a hands-on builder and a strategic technical leader — writing production code in Rust and C while simultaneously shaping the architectural direction of the Lambda Dublin organization across multiple levels. You will also play a critical role in growing the engineering team. With strong senior engineers who are deep technically but still developing their strategic thinking and organizational influence, you will mentor and coach the next generation of senior technical leaders. You will establish engineering standards, lead design reviews, and create the technical culture that enables the team to operate at the highest level. Key job responsibilities - Define and drive the long-term technical strategy for the Lambda execution environment, ensuring alignment with the broader Lambda and AWS Compute vision. - Architect and build systems for execution environment management, cold start optimization, and resource scheduling at massive scale. - Write production code in Rust and C, contributing directly to the most complex and critical components of the execution environment. - Lead the design and evolution of microVM orchestration, working closely with the Firecracker virtualization stack and Linux kernel interfaces. - Drive cross-team technical alignment with other Lambda teams, and adjacent AWS Serverless, Container and Compute teams. - Mentor and develop senior engineers, helping them grow in strategic thinking, influence, and organization-level impact. - Establish and raise the engineering bar through design reviews, technical standards, and operational excellence practices. - Represent the Lambda Experience team in senior technical forums across AWS, influencing the direction of serverless compute infrastructure. A day in the life You may start your morning reviewing operational metrics for the Lambda Execution Environment, looking at invocation latency percentiles, cold start performance, and resource utilization trends across AWS Regions. You may join a design review where a senior engineer is proposing a new approach to execution environment caching — you will ask probing questions, help them think through edge cases, and guide them toward a solution that balances performance with security isolation. Mid-morning, you may dive into code, perhaps working on a Rust component that optimizes how execution environments are pre-warmed, or investigating a subtle performance regression in the microVM boot path. After lunch, you may collaborate with the Data Plane team in Seattle that routes Lambda invocations to execution environments, aligning on an upcoming change that affects invocation routing and ensuring the execution environment architecture can accommodate new traffic patterns gracefully. You may then meet with Lambda Product Managers to discuss the customer experience, providing technical perspective on upcoming features and ensuring that the execution environment roadmap reflects customer needs and feedback. Later in the afternoon, you may spend time with your manager discussing the three-year technical roadmap and how the team's investments in next-generation scheduling will support Lambda's growth trajectory. You may end the day mentoring one of your senior engineers, helping them prepare a technical proposal that will require them to influence a partner team — coaching them on how to frame the problem, anticipate objections, and build consensus. Throughout the day, you will balance deep technical work with broad organizational influence, serving as the technical anchor for a team that is building one of the most critical execution paths in all of AWS. - Bachelor's degree in Computer Science, Engineering, a related field, or equivalent experience - Experience with virtualization (Hypervisors, VMware, Xen), or experience in software development - Experience providing technical leadership on high-impact cross-fucntional technical project - 12+ years of professional software development experience, with significant depth in systems programming. - Deep knowledge of Linux kernel internals, including process scheduling, memory management, and namespaces/cgroups. - Experience with designing and building applications using container and serverless technologies - Experience in written and verbal communication with the ability to present complex technical information in a clear and concise manner to executives and non-technical leaders - Experience as a mentor, tech lead or leading an engineering team - Experience with systems-level programming languages such as Rust and/or C/C++. - Experience optimizing cold start latency, resource scheduling, or execution environment lifecycle management in multi-tenant systems. - Experience designing and building large-scale, low-latency, highly available distributed systems. 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