ubuntu-post-install/docs/vps-sizing-recommendations.md

VPS sizing & recommended services

Reference notes from sizing this repo's services against real VPS plans. Not project documentation for contributors — a planning record for picking services against a given vCPU/RAM/disk budget.

How to size a VPS for this repo's services

For this class of self-hosted workload (web apps, a PBX, a few Docker containers — no video transcoding, no ML inference), RAM is almost always the binding constraint, not CPU or disk. CPU only matters once something is transcoding video, mixing many conference audio streams, or running local AI inference — none of which apply to most services in this repo. Disk only matters once local media storage is involved.

Rough per-service RAM budget, idle:

Kind of service	~RAM
OS + Docker daemon baseline	300-500MB
JVM apps (Traccar, UniFi)	350-500MB
App with its own Postgres/MariaDB (Mattermost, Nextcloud, Immich)	+150-250MB for the DB alone, on top of the app
Lightweight single-binary apps (Go/Rust — ntfy, vaultwarden, wg-easy, homebox, actualbudget, syncthing, portainer, coturn)	20-150MB each
Headless-Chrome-backed apps (archivebox, changedetection's JS mode)	300-500MB+

Rules of thumb:

• Keep at least 25-30% of total RAM free at idle for burst load (image pulls, log bursts, concurrent call/session spikes).
• A swapfile is cheap insurance and is now a default for every install, not just Asterisk droplets — base.sh calls lib/common.sh's ensure_swapfile() unconditionally, which offers a 2GB swapfile any time RAM is ≤4096MB and none exists yet (services/asterisk.sh also calls it directly for the standalone-run case, so it's covered either way).
• Sharing one coturn instance (services/coturn.sh) instead of letting each WebRTC-capable service (Asterisk, Mattermost) embed its own saves a container per consumer and — more importantly — avoids relay-port collisions between them.

Tier 1 — ~1 vCPU / 1GB RAM / 25GB SSD

Example: DigitalOcean Basic, $6/mo.

This is tight enough that Docker's own daemon overhead is already a meaningful fraction of the box. Pick one purpose, not a stack:

• Option A — Asterisk only. Asterisk + the shared coturn service fits comfortably per this repo's own droplet-sizing notes (services/asterisk.sh README section) — a swapfile is added automatically (RAM ≤4GB, see above), and this plan is "fine for a couple of extensions and light personal use."
• Option B — a lightweight utility box. Caddy + CrowdSec + NetBird (all near-zero RAM) plus at most one or two of the smallest apps (ntfy, vaultwarden, wg-easy) — total comfortably under 500MB.

Avoid on this tier: anything with its own database (Mattermost, Traccar, Nextcloud), more than one substantial app, media/AI/gaming services. There's no headroom for a second heavy thing once the first one is running.

Tier 2 — 4 vCores / 4GB RAM / 120GB NVMe

Example: IONOS VPS M+, $11/mo. This is the tier actually planned out in detail — see the recap below.

What I was planning for the IONOS 4 vCPU / 4GB / 120GB box

Reconstructed from the sizing conversation, in the order decisions were made:

Core stack (the original ask):

• caddy — reverse proxy / HTTPS
• crowdsec — intrusion prevention
• asterisk — PBX, using the shared coturn service (not embedded)
• mattermost × 2 — genuinely isolated instances (separate dir/containers/DB per instance), both sharing the one coturn service — this required merging PR #265 (claude/droplet-capacity-assessment-s2voix), which extracted coturn into services/coturn.sh and added real multi-instance support to services/mattermost.sh; merged into main at commit 6151ede
• traccar — GPS tracking

Validated call load: up to 9 concurrent Asterisk calls, at most 1 Mattermost call at a time, 0 screen share. Comfortably within budget — no transcoding/conferencing/heavy-video load in this profile, so CPU has large margin and RAM sits around 2.0-2.7GB idle with the core stack alone.

Utility adds, agreed:

• ntfy, wg-easy, homebox, actualbudget, mealie

Explicitly declined: vaultwarden, portainer, syncthing

Remote / cross-VLAN access: NetBird — hosted control plane (not self-hosted), client-only, with its embedded SSH server enabled (--allow-server-ssh, JWT/OIDC-based user auth, no user SSH keypair to manage). Already implemented in services/base.sh (_base_setup_netbird()) as part of every box's base install — nothing further to build for this. Chosen over self-hosting a WireGuard mesh once it was clear that (a) a hub-routed WireGuard design makes the VPS a single point of failure for inter-peer connectivity specifically, not just VPS access, and (b) a different person ever needing access means hand-editing authorized_keys on every box instead of revoking centrally — NetBird's actual value here is solving both, not just being "zero-config."

wg-easy's role, narrowed: kept in the utility-add list, but as a local-VLAN WireGuard testing ground, not the primary remote-access path — that's NetBird's job. The hub-routed peer mesh (WG_ALLOWED_IPS=0.0.0.0/0 by default, so any two enrolled peers already reach each other through the VPS with no per-pair config) plus a sync-ssh-aliases.sh companion script (reads peers straight off the live WireGuard interface via wg show, generates ~/.ssh/config Host aliases) is already built and pushed (claude/vps-capacity-assessment-r57vw3, commit 4a0ec63).

Confirmed: audiobookshelf on the VPS with HTTPS via Caddy, but pointing it at a home-hosted library over a VPN tunnel (NetBird or wg-easy, whichever link reaches that box) instead of storing audiobooks locally — services/audiobookshelf.sh already just bind-mounts a host path, so this means mounting a network share from that tunnel at the mount point instead of a local directory. Avoids the disk/CPU tradeoffs of a local media library; real bandwidth depends on home upload speed, which wasn't checked.

Music: emby, music-only — not lyrion. lyrion (LMS/Squeezebox) was floated first since it's a purpose-built, well-regarded music server, but ruled out for two protocol-level reasons neither Caddy nor Authelia can paper over: its own web-UI auth is one shared server-wide password (no per-user accounts), and its player protocol (SlimProto, port 3483) is raw TCP with no authentication of its own, so Authelia's HTTP-only forward_auth can't gate it at all. emby (already registered in this repo, media category) solves both — real per-user accounts with per-library access restriction, and every client protocol it uses is HTTP, so Caddy fronts all of it cleanly. services/emby.sh now has a music-only mode (prompts for this, defaults the folder to ~/music, and the generated README walks through adding only a Music library plus the Dashboard → Users → Access per-user restriction steps in Emby's own setup wizard). Tradeoff accepted knowingly: Emby is a generalist media server, not a purpose-built one — it lacks LMS's music-specific depth (its lyrics fetching, its many audio-focused plugins). Since there's no hardware Squeezebox tie-in to preserve, that tradeoff was fine to make.

Explicitly out of scope for this box (wrong fit, not "can't run"):

• Local media servers storing media on the VPS (jellyfin, immich, lyrion, and emby/audiobookshelf without the home-library-over-VPN approach used above) — disk-hungry, and transcoding CPU load risks contending with active calls.
• AI stacks (ai-stack, ai-gpu, iopaint, paintplus) — need real VRAM/RAM most VPS plans don't have.
• Gaming (minecraft, wolf, wolf-pair, sunshine, kyber-*) — CPU/RAM heavy; cloud-gaming ones need GPU passthrough.
• Cameras/NVR (frigate*, sky-cam) — needs real camera feeds; doesn't make sense geographically on a VPS.
• nextcloud + onlyoffice — the combined PHP+DB+office-suite stack alone would likely eat most of the remaining headroom.
• unifi — only worth ~300-500MB of Java if actually managing Ubiquiti gear from this box.
• SSH ProxyJump/bastion-hop chaining for reaching genuinely isolated (CGNAT, no local peer) boxes — a good idea in principle, parked for later since NetBird already covers the current need.

Final RAM budget for the IONOS box (everything above, idle)

Service	~RAM
OS + Docker baseline	~400MB
Caddy	~30MB
CrowdSec	~150MB
coturn (shared)	~40MB
Asterisk	~100MB
Mattermost × 2 (app+Postgres each)	~1200MB
Traccar (JVM)	~425MB
NetBird client	~35MB
ntfy, wg-easy, homebox, actualbudget, mealie	~490MB combined
audiobookshelf	~200MB
Emby (music-only)	~300MB
Total	~3.37GB

Leaves roughly ~600-700MB headroom (~16-18%) out of 4GB — tighter than the 25-30% rule of thumb above, but with the swapfile now automatic (ensure_swapfile, see above) there's real insurance against burst load rather than relying on manual setup. Deploy incrementally and check free -h / docker stats against this table rather than trusting it blindly — each line carries real estimate uncertainty, and they're stacked close enough to the ceiling that it's worth confirming. If real usage runs higher than estimated, the two Mattermost instances (~1.2GB combined) are the single biggest lever to reconsider.