[M4] Ansible Role for Log Collection

[miciav]

Description

Enhance collect playbook to gather JSONL logs from targets.

Files to modify

• lb_controller/ansible/playbooks/collect.yml
• lb_controller/ansible/roles/workload_runner/tasks/ (new tasks)

Log paths to collect

• Target nodes: {output_dir}/logs/*.jsonl, {workdir}/lb_events.stream.log
• Generator node (dfaas): k6 logs da {k6_workspace}/k6.log
• Controller: log locali

Naming convention

benchmark_results/{run_id}/logs/
├── runner-{target_host}.jsonl      # Da ogni target node
├── k6-{generator_host}.jsonl       # Da generator node (dfaas)
└── controller.jsonl                # Log controller locale

Nota: La raccolta dei log k6 dal generator è specifica del plugin dfaas.

Acceptance criteria

• Collects all JSONL logs
• No naming collisions
• Works with multiple hosts

Milestone: M4 - Log Collection Enhancement
Issue: 4.1

[miciav]

Implemented log collection for lb_events.stream.log and DFaaS generator k6.log in lb_controller/ansible/playbooks/collect.yml. Updated tests in tests/unit/lb_controller/test_collect_playbook.py.