Fix Nexus Ubuntu apt proxy pinned to bionic, breaking package installs on jammy VMs

[Copilot]

Resolves #4992

What is being addressed

The Nexus shared service Ubuntu apt proxy repositories were configured with "distribution": "bionic" (Ubuntu 18.04). Guacamole Linux VMs run Ubuntu 22.04 (jammy) and request jammy packages — Nexus couldn't proxy them, returning 502 errors. With set -o errexit in vm_config.sh, the first apt install failure (gnupg2, gdebi-core, debconf-utils) aborts the entire bootstrap, leaving the VM unconfigured and blocking Guacamole connections.

How is this addressed

• ubuntu_proxy_conf.json: "distribution": "bionic" → "jammy"
• ubuntu_security_proxy_conf.json: "distribution": "bionic-security" → "jammy-security"
• porter.yaml: version bump 3.10.0 → 3.10.1
• CHANGELOG.md: bug fix entry added

The Nexus configure_nexus_repos run command re-applies all repo configs on upgrade, so existing deployments pick up this fix without VM recreation.

• Fixes Guacamole Linux VM vm_config.sh fails and prevents guacamole connections #4992

[marrobi]

@copilot we need to leave the old one for older VMs. We need to proxy for multiple releases.

[Copilot]

@copilot we need to leave the old one for older VMs. We need to proxy for multiple releases.

Done. I've reverted ubuntu_proxy_conf.json and ubuntu_security_proxy_conf.json back to bionic/bionic-security (preserving support for older VMs) and instead added two new proxy repo configs:

• ubuntu_jammy_proxy_conf.json (name: ubuntu-jammy, distribution: jammy)
• ubuntu_security_jammy_proxy_conf.json (name: ubuntu-security-jammy, distribution: jammy-security)

The Guacamole Linux VM's apt_sources_config.yml now points to the new jammy-specific repos. (commit Keep bionic repos, add jammy-specific Nexus apt proxy repos and update linuxvm apt sources)

[marrobi]

@copilot

Confirmed design: A Nexus apt group repo can front multiple apt proxy members each pinned to a different distribution (bionic/jammy). Clients hit one stable group URL and their own $RELEASE codename routes to the right member — exactly the multi-distro support you want, keeping bionic for backward compat.
Scope: Rework ubuntu, ubuntu-security, and docker into {name}-bionic + {name}-jammy proxy members behind a group that keeps the stable client-facing name, so existing consumers need no edits. Revert PR #5003's jammy-specific apt_sources_config.yml URLs back to the stable group names.
Microsoft apt: flagged for investigation (its remoteUrl is just the host root with per-distro paths), with a documented outcome required.
Loader: no changes needed, but the agent must verify member-before-group create ordering in configure_nexus_repos.sh and match the Nexus REST group.memberNames schema.
Also updates: CHANGELOG, docs/.../nexus.md table, porter.yaml version, and the PR #5003 description rewrite.

[Copilot]

@copilot

...

Done in commit Rework ubuntu/ubuntu-security/docker into group+member apt repos for multi-distro Nexus proxy support.

What was implemented:

• ubuntu / ubuntu-security / docker: Each is now a trio of {name}-bionic proxy + {name}-jammy proxy + {name} apt group. Clients hit the stable group URL (/repository/ubuntu/, /repository/ubuntu-security/, /repository/docker/) and Nexus routes to the correct per-distribution member. Existing consumers (VMs, sources lists) require no changes.

• apt_sources_config.yml: Reverted back to stable group URLs (ubuntu/, ubuntu-security/).

• configure_nexus_repos.sh: Refactored to a two-pass loop — all non-group repos are created/updated first (Pass 1), then group repos (Pass 2). This guarantees proxy members exist before groups are registered.

• microsoft-apt investigation: The proxy uses remoteUrl: "https://packages.microsoft.com" (host root) with per-product paths baked into the client's sources list (e.g., /ubuntu/22.04/prod, /repos/edge). Since all current VM images use apt_sku: 22.04 (Ubuntu 22.04/jammy), the distribution was updated bionic → jammy. The group/bionic+jammy pattern was not applied here — the apt_sku path already encodes the Ubuntu version, and the stable distribution entries (/repos/edge, /repos/vscode) don't vary by Ubuntu release.

• nexus.md: Current Repos table updated with group/member rows and a note on microsoft-apt.