About this role
Job Description: About Organization Security Engineering & Operations Department supports Rakuten Mobile and related services by providing robust security infrastructure, network security, identity/access management, and security operations platforms. As our business scales, ensuring secure and reliable operations across on-premises, cloud, and Kubernetes environments is mission-critical.
To support Rakuten Mobile’s rapid growth, we are continuously expanding our Linux/Kubernetes-based platforms and enhancing our authentication and secrets management capabilities. We are seeking an experienced engineer with 8+ years of hands-on expertise to accelerate stable operations, drive standardization, and elevate the security quality of our mission-critical infrastructure. The Network Security Engineering Section designs and operates secure network services using an advanced technology stack including Linux, RHEL, Kubernetes, IPA/FreeIPA, and Vault.
Job Duties
• Linux Infrastructure: Design, build, operate, and troubleshoot Red Hat Enterprise Linux and diverse Linux environments. • Kubernetes Security: Securely operate, configure, and optimize Kubernetes clusters and related components to meet growing operational demands. • Identity & Access Management: Manage authentication, user lifecycle, authorization, and policies using IPA/FreeIPA. • Secrets & Certificate Management: Design and operate secrets management, PKI/certificate management, and access control using HashiCorp Vault or equivalent tools. • Security Hardening: Perform security hardening, patch management, and audit support for Linux/Kubernetes environments to ensure high security standards. • Automation: Drive configuration management, automation, and standardization using tools such as Ansible to improve operational efficiency. • Incident Management: Handle incidents, conduct root-cause analysis (RCA), and implement preventive measures for mission-critical services. • Cross-functional Collaboration: Work closely with network, cloud, security, and operations teams, utilizing English for technical communication and project coordination in a global environment.
Minimum Qualifications
• 8+ years of hands-on experience designing, building, and operating Linux/RHEL environments. • Proven experience in operating, configuring, and troubleshooting Kubernetes environments. • Practical experience with authentication platforms (IPA/FreeIPA), including user and authorization management. • Practical experience with secrets management, certificate management, and access control (Vault or equivalent). • Strong background in Linux security hardening, patch management, and vulnerability remediation. • Fundamental knowledge of networking, DNS, TLS/PKI, firewalls, and load balancers. • Strong analytical skills to independently handle incidents, analyze root causes, and improve operational processes. • Professional proficiency in English (technical documentation, communication, and collaboration).
Preferred Qualifications
• Experience operating large-scale telecommunications, cloud, or mission-critical infrastructure. • Automation experience using Ansible, Terraform, Python, or Shell scripting. • Deep knowledge of Kubernetes security (RBAC, NetworkPolicy, container image management). • Experience with monitoring, log analysis, SIEM integration, and incident response workflows. • Relevant certifications such as RHCE, CKA, CKS, or other security-related credentials. • Experience driving projects within global teams and managing multiple stakeholders.
Work Environment
• Department: Network Security Engineering Section, Security Engineering Department. • Collaboration: Work alongside global teams with diverse backgrounds in Linux, networking, security, cloud, and Kubernetes. • Stack: RHEL, Kubernetes, IPA/FreeIPA, Vault, Ansible, Git, CI/CD, and various monitoring/logging tools across on-premises and cloud environments.
Languages: English (Overall - 3 - Advanced)