Staff Software Engineer (f/m/d) Virtual Network Functions

About IONOS At IONOS, we don't just manage servers – we shape the digital future for more than 6.2 million customers worldwide with our solutions. As Europe's leading hosting provider and a pioneer in independent cloud solutions, we are building next-generation infrastructure – from sovereign cloud architectures and high-performance GPU clusters to integrated AI automation tools. What drives us is digital sovereignty for Europe and real impact for small and medium-sized businesses (SMBs) as well as large enterprises. We work in agile teams, rely on transparent structures, and believe that excellence and innovation only emerge through true team spirit. Ready for your next step? Become part of IONOS and grow with us. The IONOS Cloud VNF Development team is seeking a highly motivated and experienced software engineer. The VNF Development team designs, develops and maintains the Virtual Network Functions (VNF) behind IONOS Cloud's network offerings. These products serve both our external customers and other internal IONOS teams. We build our VNFs in Golang and run them on Kubernetes, so the team works across the whole lifecycle: architecture, implementation, deployment and day-to-day operations. As part of the team, you'll play a crucial role in shaping and running these products. We are looking for someone to join our team and work with us on providing the best VNF products possible. Tasks Developing and supporting our multiple modern, scalable and high-performance Virtual Network Functions (VNF) offerings of IONOS Cloud using a range of diverse technologies. Designing new features and adopting new technologies (both hardware and "software defined") on different components of the VNF infrastructure. Writing, testing and reviewing Golang services for our VNFs, using AI-assisted tooling as part of your daily development workflow. Deploying, operating and troubleshooting VNF workloads on Kubernetes, including cluster operations, upgrades, monitoring and debugging network issues in production. Cooperating with other teams to ensure the smooth integration of new Virtual Network Functions with different IONOS products. Qualification Proficiency in Golang and/or C/C++, including AI-assisted development. Hands-on experience with Kubernetes architecture and operations; knowledge aligned with CKA (Certified Kubernetes Administrator) principles. Knowledge of the TCP/IP protocol family and networking technologies such as Open vSwitch, OpenFlow, VXLAN, VRF and eBPF. Experience with cloud environments and virtualization technologies like QEMU/KVM. Experience with the GNU toolchain (gcc, gdb, make, etc.), git and the Linux CLI. Experience with Linux system administration and automation. Nice to have: Linux kernel networking internals, VPP and DPDK. Benefits Hybrid working model. Flexible working hours through trust-based working hours. At some locations a subsidized canteen and various free drinks. Modern office space with very good transport connections. Various employee discounts for activities and products. Employee events such as summer and winter parties, as well as workshops. Numerous training and development opportunities. Various health offers, such as sports and health courses. Application Note We value diversity and welcome all applications – regardless of, for example, gender, nationality, ethnic or social origin, religion, disability, age as well as sexual orientation and identity, physical characteristics, marital status or any other irrelevant factor subject to applicable law.