Senior Middleware Administrator

📍 Wrocław / Warsaw / Kraków | Remote with occasional visits to the office
💼 Full-time, B2B contract

About the Role

We are looking for an experienced Senior Middleware Administrator to join our team and support enterprise-grade middleware environments. In this role, you will be responsible for the installation, configuration, administration, optimization, and lifecycle management of critical middleware platforms that support high-availability enterprise applications.

You will work closely with engineering, infrastructure, and DevOps teams to ensure secure, stable, and high-performing application environments across multiple middleware technologies.

Key Responsibilities

Middleware Installation & Configuration

• Install, configure, and upgrade middleware platforms including JBoss EAP, WebLogic, Apache Tomcat, IBM WebSphere, GlassFish, and Payara

• Configure JVM parameters, domains, clusters, thread pools, data sources, JDBC, JMS, and deployment descriptors

• Implement SSL/TLS certificates, keystores, truststores, and security configurations

Administration & Platform Maintenance

• Manage application deployments and server lifecycle (start/stop, managed servers, domain controllers)

• Maintain log rotation, patching, backups, and middleware resource management

• Perform performance profiling and analysis using heap dumps and thread dumps

High Availability & Clustering

• Configure clustering, load balancing, and distributed middleware environments

• Implement session replication, distributed caching, and failover mechanisms

• Conduct HA testing, disaster recovery (DR) failover exercises, and cluster validation

Performance Optimization

• Tune JVM parameters (heap memory, garbage collection algorithms)

• Optimize thread pools, connectors, and caching mechanisms

• Troubleshoot high CPU usage, memory leaks, GC pauses, and application performance issues

Security & Compliance

• Implement authentication, authorization, encryption, and SSL/TLS policies

• Harden middleware platforms and ensure compliance with enterprise security standards

Troubleshooting & Incident Management

• Analyze server logs, GC logs, thread dumps, and access logs

• Resolve HTTP errors, deployment failures, connectivity issues, and performance bottlenecks

• Perform root cause analysis (RCA) and implement preventive improvements

Automation & Scripting

• Automate operational tasks using Bash, PowerShell, WLST, Jython, or shell scripting

• Maintain configuration versioning using Git or SVN

Lifecycle & Decommissioning

• Plan and execute middleware decommissioning and environment cleanup

• Archive logs, remove unused configurations, and maintain CMDB records

Required Qualifications

• 6+ years of hands-on experience administering enterprise middleware platforms

• Strong experience with JBoss, WebLogic, Tomcat, WebSphere, GlassFish, or Payara

• Solid understanding of Java application hosting, JVM tuning, clustering, and high availability

• Strong knowledge of Linux/Unix and Windows server environments

• Proven ability to troubleshoot performance issues using logs, heap dumps, and thread dumps

Nice to Have

• Experience with Nginx, Apache HTTPD, or reverse proxy configurations

• Experience with containers and orchestration (Docker, Kubernetes)

• Monitoring tools such as Grafana, Prometheus, Dynatrace, or AppDynamics

• Experience integrating middleware deployments into CI/CD pipelines

Certifications (Preferred)

• Middleware or Web Server certifications

• ITIL Foundation

What We’re Looking For

• Strong ownership mindset and analytical problem-solving skills

• Excellent communication and documentation abilities

• Ability to work independently in complex production environments

• Comfortable handling critical incidents and production support

Additional Information

• Standard business hours with on-call support

• Participation in planned maintenance windows and emergency fixes when required