[Feature]: Golden container disk image with pre-installed workload tools

[mrhillsman]

Problem Statement

Virtwork currently installs workload tools (stress-ng, fio, iperf3, pgbench) at VM boot time via cloud-init package installation. This approach adds boot latency, depends on external package repositories being available, and increases the chance of transient failures during provisioning.

Proposed Solution

Build a pre-baked golden container disk image with all workload tools pre-installed. VMs would boot ready to run workloads immediately, with no package installation step required.

The golden image should include:

• stress-ng — CPU/memory workloads; also supports thermal, I/O, and scheduler stress
• fio — Disk workloads; can simulate disk saturation scenarios
• iperf3 — Network workloads
• pgbench / postgresql-server — Database workloads
• tc (traffic control) / iproute-tc — Network chaos: latency injection, packet loss, bandwidth throttling
• iptables-nft — Network partition simulation, port blocking
• kill / pkill — Process chaos (available by default in base image)
• fallocate / dd — Disk fill chaos
• tc-netem — Advanced network emulation (jitter, reordering, duplication)

Files to Create

• build/golden-image/Containerfile — Multi-stage build definition based on Fedora 41 with all tools pre-installed

Files to Modify

• internal/workloads/cpu.go — Remove dnf install from cloud-init; assume stress-ng is pre-installed
• internal/workloads/memory.go — Remove dnf install from cloud-init; assume stress-ng is pre-installed
• internal/workloads/database.go — Remove dnf install from cloud-init; assume postgresql-server and pgbench are pre-installed
• internal/workloads/network.go — Remove dnf install from cloud-init; assume iperf3 is pre-installed
• internal/workloads/disk.go — Remove dnf install from cloud-init; assume fio is pre-installed
• internal/constants/defaults.go — Update default container disk image to the golden image

Expected Outcome

• A Containerfile in build/golden-image/ that extends quay.io/containerdisks/fedora:41 and installs all required packages
• Image published to a container registry (e.g., quay.io/opdev/virtwork-golden:latest)
• Default --container-disk-image value updated to point to the golden image
• All existing workload cloud-init scripts simplified to remove package installation steps
• Cloud-init scripts only configure and start systemd services
• Boot time reduced significantly

Alternatives Considered

Not provided

Area

CLI / Configuration, VM provisioning, Workloads

Additional Context

This feature is a prerequisite for the chaos engineering workload requests. The chaos workloads depend on tools (tc, iptables, etc.) being pre-installed in the golden image.

Related Issues: See chaos workload requests that depend on this issue.

Split from #15