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ac-docs/DRs/20100612_1_scaling.md
Anton Afanasyeu 69a448f156 initial
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Platform scaling and multi-environment architecture — design review (DR)

Field Value
Author Anton Afanasyeu
Revision R1
Creation date 2026-06-12
Last modification date 2026-06-12
Co-authored
Severity medium
State pending review
Document type DR

\newpage \newpage

Document type: DR (Design Review)
Source draft: docs/drafts/20100612_1_scaling.txt
Specification: docs/specs/20100612_1_scaling.md
PDF: 20100612_1_scaling.pdf · Regenerate: bash scripts/build-all-docs-pdf.sh (Mermaid → PNG diagrams; requires npx)
Date: 2026-06-12
Status: Reviewed — planning / brainstorming (no implementation sprint yet)
Severity: Strategic

Documentation index: README.md

Documentation index: README.md

Table of contents

Documentation index: README.md

1. Executive summary

The project outgrew one Alpine BE VM that hosts consoles, APIs, MariaDB, Gitea, OTA, WireGuard, RSSH, URL shortener, and Docker builds. The draft asks for clusters, dev/staging/prod, zero-downtime deploys, optional cloud, and headroom for RT cast, VPN commercialization, payments, and ffmpeg pipelines.

DR outcome:

Area Decision
Timing Post-alpha strategic track; does not block alpha soak
Architecture Option B → A phased: minimal VM split first, then full dev cluster simulation
Edge Keep Gentoo FE as TLS/DNAT anchor; add LB upstream to N BE web nodes
Data Dedicated MariaDB VM before scaling anything else CPU-heavy
Build First split candidate — Docker off shared PHP VM
Cloud Hybrid — object store + staging dress rehearsal before prod migration
RSSH capacity Plan 100 concurrent SSH / 5k heartbeats per bastion pair before commercial VPN
Bandwidth Document WAN / FE→BE / per-service Mbps & GB-month budgets (SPEC §12.3); CDN before horizontal web scale for OTA
Global + GEO Worldwide reach default; deny segments per content (e.g. no serve in ZM) via layered enforcement (SPEC §14)
Future slots Weighted backlog in §9; SFU before ffmpeg farm; F10 GEO with F3/F5

2. Problem statement

Pain Evidence today
Blast radius Submodule sync wiped gitignored configs; one BE restart affects all services
Resource contention Docker build spikes CPU/RAM during PHP console use
No promotion path Single prod-like env; staging OTA path still pending (20260608_BE_SERVICES_and_infra.md)
Scaling ceiling RSSH + WG + future SFU on same VM as MariaDB
Bandwidth ceiling Single FE WAN + FE→BE path; OTA/APK egress competes with consoles (SPEC §12.3)
GEO gap No per-content region policy yet; required before global recordings/commerce (SPEC §14)
Operational risk Topology changes on FE/router are hard to roll back (bottomline_reminder.txt)

Success criteria: PO can deploy unstable work to dev, beta-test on staging, and promote to prod with rollback per service — without rewriting mobile apps or public URLs each time.

3. Architecture options

3.1 Option A — Dev cluster (draft default)

Draft proposal: N VMs per environment, each role class (web+OTA, DB, object store, WG, url shortener+Gitea, build, +N for new features).

flowchart TB
    subgraph Cluster["One environment cluster (e.g. dev)"]
        W["Web + OTA VM(s)"]
        D["Database VM(s)"]
        O["Object store VM(s)"]
        V["WireGuard VM(s)"]
        U["URL shortener + Gitea VM"]
        B["Build VM(s)"]
        X["Future service VM(s)"]
    end
    W --> D
    W --> O
    U --> D
    B --> O
    V --> W
Pros Cons
Clear isolation; matches future SFU/ffmpeg Highest VM count / cost
Easy to simulate on FE XEN Ops overhead for small team
Aligns with cloud MIG later Overkill before alpha exit

3.2 Option B — Tighter cost (minimal split)

Phase 1 prod shape (recommended start):

VM Bundled services
be-web nginx, PHP (hub, crashes, graphs, builder UI, OTA metadata)
be-data MariaDB only
be-ops Gitea, url-shortener
be-build Docker builder
be-vpn WireGuard + RSSH bastion 
flowchart LR
    FE["Gentoo FE"] --> WEB["be-web"]
    WEB --> DATA["be-data"]
    WEB --> VPN["be-vpn"]
    OPS["be-ops"] --> DATA
    BUILD["be-build"] --> DATA
Pros Cons
~5 VMs vs 7+; fits “money-wise” draft Gitea + shortener still coupled
Unblocks build/DB contention immediately Second web node needed later for true HA
Low risk to current URLs WG still single point until pool

3.3 Option C — Cloud-first hybrid

Move staging entirely to GCP/Azure; keep prod on FE→BE until hybrid LB proven.

Pros Cons
Managed LB, DB, object store day one Egress cost; UDP/WG complexity
Dress rehearsal for full cloud PO learning curve; vendor lock-in mild
ffmpeg/SFU elastic scale Violates “safest topology” unless staged

3.4 Comparison matrix

Scores 1 (poor) – 5 (excellent) for current team size and alpha proximity:

Criterion A — Full cluster B — Minimal split C — Cloud-first
Cost now 2 4 3
Time to first value 2 5 3
Zero-downtime readiness 4 3 5
Topology safety 4 5 2
SFU/ffmpeg fit 5 3 5
Simulation fidelity 5 4 2
Global CDN / GEO 3 3 5
Weighted total 25 27 25

Weights used: safety and cost now > cloud elasticity pre-alpha.

4. DR decision — recommended path

Now ──► Option B (minimal split) on-prem HVMs
          │
          ├── Simulate Option A as DEV cluster (3–7 Alpine HVMs)
          │
          ├── Add be-web-2 + FE upstream when metrics say so
          │
          └── Option C for staging only → then hybrid prod
Step Action Owner
1 Document service boundaries (this SPEC/DR) Agent / PO review
2 Move Docker builder to be-build-1 Sysop
3 Move MariaDB to be-data-1 (hardest cutover) Sysop
4 Stand up dev cluster simulation on intra network Sysop
5 Staging promotion runbook + DNS prefix PO + DEV
6 Cloud object store for OTA/APK Sysop
7 CDN + bandwidth dashboards (SPEC §12.3) Sysop
8 SFU SPEC + media workers (separate track) PO spec
9 GEO policy schema + edge rules (SPEC §14) PO + DEV

Not chosen now: full Option A in prod; full Option C prod cutover.

5. Current vs target diagrams

Today (single BE)

flowchart TB
    R["Router 134.17.26.161"] --> FE["FE Gentoo 10.7.0.10"]
    FE --> BE["Single Alpine BE 10.7.16.128"]
    BE --> S1["PHP consoles + APIs"]
    BE --> S2["MariaDB"]
    BE --> S3["Gitea + url-shortener"]
    BE --> S4["Docker build"]
    BE --> S5["WG + RSSH"]
    FE -->|"UDP 45340 DNAT"| S5

Target phase B (minimal split + HA web)

flowchart TB
    R["Router"] --> FE["Gentoo FE"]
    FE --> LB["nginx upstream / cloud LB"]
    LB --> W1["be-web-1"]
    LB --> W2["be-web-2"]
    W1 --> DB["be-data MariaDB"]
    W2 --> DB
    OPS["be-ops Gitea+shortener"] --> DB
    BUILD["be-build Docker"] --> DB
    VPN1["be-vpn-1"] --> DB
    VPN2["be-vpn-2 optional"]
    FE -->|"UDP DNAT pool"| VPN1
    FE --> VPN2

6. Service split rationale

Draft asked to balance cost vs CPU/RAM needs. DR sizing rules:

Workload CPU RAM Disk Pin to
PHP consoles Medium 2–4 GiB Small be-web*
MariaDB Medium 8+ GiB Fast SSD be-data
Gitea mirrors Low 2 GiB Medium be-ops
URL shortener Low 512 MiB Tiny be-ops
Docker build Burst high 16 GiB Large ephemeral be-build
WireGuard Low 1 GiB Tiny be-vpn
RSSH sshd Low–med 2 GiB Tiny be-vpn
ffmpeg (future) Sustained high 8–32 GiB Temp SSD be-media*
SFU (future) High 8+ GiB Low be-media*
Recordings (future) Low — Large object store

Anti-pattern rejected: MariaDB + Docker build + ffmpeg on one VM (draft implied bundle risk).

7. Environment promotion model

Gate dev → staging staging → prod
Automated tests ./gradlew :app:testDebugUnitTest + BE smoke + soak checklist
Manual PO feature acceptance PO sign-off + tag
Data Synthetic Anonymized copy optional
Rollback Re-deploy previous image Git revert + DB restore runbook

Align app releases with GIT_FLOW.md; infra releases may cadence independently with config version pins per environment.

8. RSSH and connection capacity

Draft question: how many simultaneous connections per instance?

Assumptions

  • Heartbeat poll 1–7 min (REMOTE_ACCESS_IMPL)
  • Average SSH session 15 min operator work
  • Alpine be-vpn-1: 2 vCPU, 2 GiB RAM

Estimates

Resource Limiting factor Conservative With tuning
Concurrent SSH sshd MaxSessions / CPU 50 100
Devices polling heartbeat PHP-FPM + MariaDB writes 2 000 5 000
New SSH/min MaxStartups 10 30
WG peers (lab) kernel + UDP 200 500 / 2 nodes

Tuning knobs: separate heartbeat PHP pool to be-web (off bastion); keep sshd on be-vpn only; connection pooling to MariaDB; read replicas for heartbeat read-heavy phases.

DR recommendation: Instrument active SSH and heartbeat QPS in graphs before selling commercial VPN (draft F4).

8b. Network bandwidth (DR)

Draft rev.2 adds throughput alongside connection counts.

Baseline risk (today)

Path Risk
Single WAN uplink OTA release or viral short link saturates all services
FE→BE proxy All HTTPS doubles through FE NIC
No CDN Every APK download hits origin BE
Media future SFU + ffmpeg on same uplink = hard fail without PoP/CDN

DR sizing decisions

Decision Rationale
CDN before be-web-N for OTA/static Fixes egress Mbps cheaper than more PHP VMs
Separate media NIC/subnet when SFU lands Isolate UDP/WebRTC from MariaDB LAN
Egress budget alerts at 80% ISP/cloud quota PO notified before hard cap
Simulate release day on staging e.g. 1000 concurrent OTA downloads

Planning numbers (single-site prod, until CDN)

Traffic Peak Mbps (conservative) Mitigation
Steady HTTPS (API + consoles) 5–20 Normal
OTA drop (1000 devices × 40 MB APK) 200–400 burst 10 min CDN required
Recording download (F3) 50–200 per hot file Object store + CDN signed URLs
SFU fan-out 100 viewers 50–500+ Regional PoP; not on FE WAN

Full table: SPEC §12.3.

8c. Global availability and GEO segments (DR)

Draft rev.2: global reach + segment isolation (example: deny publish/serve in Zambia ZM).

Policy model (DR decision)

Rule Choice
Default Allow worldwide for control plane and public APIs
Content objects Attach optional geo_policy with deny_publish / deny_serve / allow_only
Enforcement order CDN/WAF → BE API (trusted geo header) → object signed URL → app entitlement
Operator UI Hub/console editor for geo segments when F3/F10 ship — not alpha
Sanctions PO-maintained deny lists; not auto-synced from external API in v1 
flowchart LR
    REQ["Client request"] --> EDGE["CDN / FE edge"]
    EDGE --> GEO{"Country in deny_serve?"}
    GEO -->|yes| DENY["451 / blocked manifest"]
    GEO -->|no| BE["BE + geo_policy DB"]
    BE --> OK["200 / stream / redirect"]

Phasing

Phase GEO capability
Now Implicit worldwide; no per-content rules
CDN phase Edge geo block for coarse country bans
F3 storage Per-recording geo_policy in MariaDB + object metadata
F5 payments Entitlement includes geo_allowed
Multi-PoP GeoDNS routes to nearest allowed PoP only

Example use cases

Use case Policy
OTA stable globally default: allow
Beta APK EU-only allow_only: ["DE","FR",…]
Recording licensed EU/US only deny_serve: ["ZM",…] + allow_only optional
Short link to blocked catalog BE returns 451 at redirect time

Open for PO: whether VPN exit in denied country circumvents policy (DR: log + ToS; technical block on VPN product separate from HTTP geo).

9. Future capabilities — priority weighting

Weighted for platform dependency and revenue enablement (PO may override):

Rank Slot Weight Rationale
1 F1 Multipoint cast (SFU/MCU) Critical path Unblocks WAN cast; already on OPEN_TASKS_GRAPH.md
2 F2 ffmpeg transcode High Shared worker pool for F3, F9
3 F3 Cast storage High Needs F1+F2 + object store
4 F5 Payments Medium Enables F3, F4, F7
5 F4 Commercial VPN Medium RSSH/WG scale must be proven first
6 F9 3rd-party streaming Medium Uses F2 cast handlers
7 F6 Mobile add-ons Lower Can ship on-device first
8 F7 In-app transfers Lower Compliance heavy
9 F8 DNS / subdomains Exploratory Largest scope creep
10 F10 GEO enforcement Medium Required for F3/F5 global commerce; draft rev.2 
flowchart TB
    SFU["F1 SFU / multipoint"] --> STORE["F3 Cast storage"]
    FF["F2 ffmpeg workers"] --> STORE
    FF --> EXT["F9 3rd-party streams"]
    SFU --> EXT
    PAY["F5 Payments"] --> STORE
    PAY --> VPN["F4 Commercial VPN"]
    PAY --> XFER["F7 In-app transfers"]
    PAY --> ADD["F6 Add-ons"]
    DNS["F8 DNS / site builder"] --> PAY
    GEO["F10 GEO policy"] --> STORE
    GEO --> PAY

10. Simulation lab design

Sysop simulates Option A under dev without WAN changes:

HVM Alpine packages Role
dev-web-1 nginx, php81-fpm Web tier
dev-data-1 mariadb DB
dev-ops-1 git, gitea (optional) Gitea + shortener
dev-build-1 docker Builder
dev-vpn-1 wireguard-tools, openssh VPN lab

Network: 10.7.0.0/8 only; FE routes dev.apps.f0xx.org to dev-web when ready.

Deliverable suggestion: docs/SIMULATION_CLUSTER.md + scripts in phase 1 — not blocking this DR.

11. Cloud provider notes (GCP / Azure)

Concern GCP Azure
Managed LB ILB + NEG App Gateway / Front Door
Object store GCS Blob
Managed MariaDB Cloud SQL Azure Database for MariaDB
UDP / WG harder harder — keep on-prem FE DNAT longer
ffmpeg burst MIG (CPU) VMSS
Egress cost Watch OTA/APK Same
CDN + geo WAF Cloud CDN / Cloud Armor Azure Front Door + rules
Multi-region GCS dual-region; Cloud CDN PoPs Blob + AFD PoPs

DR: Use cloud for staging cluster first (Option C partial) — validates IaC without prod risk. CDN geo rules prototype on staging before prod F3.

12. RBAC evolution

Stage Who Access
Alpha (now) Developers = operators Max privileges; shared session
Beta Split developer vs support operator Tickets/RA without build admin
Commercial Customer admin + platform admin Tenant isolation; audit export

New roles MUST NOT require mobile app changes until F5 entitlements API exists.

13. Risks and mitigations

Risk Impact Mitigation
MariaDB migration downtime Prod outage Replica + cutover window; practice on dev
Config loss on sync 503 (seen url-shortener) ensure_* scripts; secrets outside tree
FE upstream misconfig Partial outage nginx -t; weighted rollout
WG UDP cloud move VPN breaks Keep DNAT path until PO signs UDP plan
Over-scoping F5–F9 Never ship SFU §9 order
WAN saturation on OTA Global outage perception CDN + §8b budgets
Geo policy bypass via VPN Compliance / licensing Separate VPN egress policy; audit logs
Wrong deny list Legitimate users blocked Staging test + X-Debug-Country; PO approval workflow
Simulation sprawl Sysop time Cap dev HVMs at 7; destroy scripts

14. Estimates

Person-days (single sysop + DEV support), planning accuracy ±40%:

Phase Work Days
P0 SPEC/DR + simulation design (this doc) 2
P1 Split Docker build VM 2
P2 MariaDB dedicated VM + migration 3
P3 be-ops split (Gitea + shortener) 1
P4 Dev cluster HVM simulation (5 VMs) 4
P5 Staging env + promotion runbook 3
P6 be-web-2 + FE upstream HA 2
P7 Cloud object store for OTA 2
P7b CDN + bandwidth metrics on graphs 2
P8 GEO policy schema + staging CDN geo test 3
P9 SFU/media (separate SPEC) TBD
Total (through P7b) ~21 days

Severity: Strategic — parallel to alpha; no alpha gate.

15. Task dependency graph

Legend: 1 = highest priority (PO: post-alpha infra). Assignee Sysop = PO today; Agent = documentation/automation; DEV = app/config changes.

flowchart TB
    T1["1. SPEC+DR scaling docs<br/>Agent ✓"]
    T2["2. Split be-build Docker<br/>Sysop"]
    T3["3. Dedicated be-data MariaDB<br/>Sysop"]
    T4["4. ensure_* config hardening all services<br/>Agent"]
    T5["5. Dev cluster simulation HVMs<br/>Sysop"]
    T6["6. Staging env + DNS prefix<br/>Sysop + PO"]
    T7["7. Promotion runbook dev→stg→prod<br/>PO"]
    T8["8. be-web-2 + FE upstream<br/>Sysop"]
    T9["9. Cloud object store OTA<br/>Sysop"]
    T9b["9b. CDN + bandwidth metrics<br/>Sysop"]
    T10["10. GEO policy + edge rules<br/>PO+DEV"]
    T11["11. SFU owner SPEC<br/>PO"]
    T12["12. ffmpeg worker pool<br/>DEV post-SFU"]
    T13["13. Payments / entitlements SPEC<br/>PO"]

    T1 --> T2
    T1 --> T4
    T2 --> T3
    T3 --> T5
    T4 --> T6
    T5 --> T6
    T6 --> T7
    T7 --> T8
    T3 --> T8
    T8 --> T9
    T9 --> T9b
    T9b --> T10
    T10 --> T11
    T11 --> T12
    T12 --> T13

    style T1 fill:#86efac,color:#14532d
    style T11 fill:#e5e7eb,color:#374151
    style T12 fill:#e5e7eb,color:#374151
    style T13 fill:#e5e7eb,color:#374151
ID Task Assignee Blocks
1 Scaling SPEC/DR Agent —
2 Docker → be-build Sysop DB split
3 MariaDB → be-data Sysop HA web
4 Post-sync config scripts (all services) Agent staging
5 Dev HVM simulation Sysop staging realism
6 Staging cluster Sysop promotion
7 Promotion runbook PO prod multi-node
8 Second web node Sysop cloud OTA
9 Object store OTA Sysop CDN
9b CDN + bandwidth dashboards Sysop GEO test
10 GEO policy + edge PO+DEV F3 commerce
11 SFU SPEC PO media workers
12 ffmpeg pool DEV commercial storage
13 Payments SPEC PO F6–F8

Parallel now (non-blocking): alpha soak, url-shortener ops, Gitea mirrors, ticket SVC-OTA.

16. Resolved open questions

# Draft question DR answer
Q1 How many VMs in a cluster? Option B: 5 prod VMs to start; dev simulation: 3–7 (SPEC §6.3)
Q2 “Other” architecture approaches? Option C hybrid for staging; not prod-first (§3.3)
Q3 Cost vs CPU/RAM balance? Split by §6 profile table
Q4 Seamless scaling / LB? FE upstream → N PHP nodes; cloud managed LB in phase 5 (SPEC §9)
Q5 Simultaneous connections / RSSH? §8 — 100 SSH, 5k heartbeats per bastion pair (tuned)
Q6 Alpine simulation? §10 — intra 10.7.0.0/8 HVMs only
Q7 Future MCU/SFU/ffmpeg/storage/VPN/payments? Platform slots F1–F9; priority §9
Q8 RBAC model change? §12 three-stage
Q9 Keep current topology safe? Yes — SPEC §18
Q10 Network bandwidth metrics? §8b + SPEC §12.3 — CDN before web horizontal scale
Q11 Global availability + GEO deny (e.g. Zambia)? §8c + SPEC §14 — default allow, per-content deny

17. Remaining open items (PO)

ID Question Needed for
O1 Target monthly infra budget for phase B (5 VMs)? Option A vs B timing
O2 Staging URL pattern: staging.apps.f0xx.org vs path prefix? DNS + TLS
O3 Cloud vendor preference GCP vs Azure vs none for 12 months? P7–P9
O4 Accept maintenance window for MariaDB cutover (minutes of read-only)? P2 schedule
O5 Commercial VPN — same WG infra or separate product stack? F4 design
O6 SFU — Janus on :8089 vs greenfield mediasoup? F1 SPEC (20260608_BE_SERVICES_and_infra.md)
O7 Payments — Stripe-only vs multi-provider? F5 SPEC
O8 ISP/cloud egress cap (GB/month) on FE WAN? §8b budgets
O9 CDN provider (Cloudflare vs cloud-native vs none 12 mo)? OTA + GEO WAF
O10 GEO deny lists — PO-owned static JSON vs admin UI first? F10 rollout
O11 Recordings 451 vs silent 404 for denied regions? UX + compliance

When blocked on O1–O7, append to tmp/YYYYMMDD_implementation_summary.pdf per bottomline_reminder.

18. Suggestions (PO / dev discretion)

# Suggestion
S1 Add infra smoke to validate_be_services.sh per VM role after split
S2 Version nginx upstream fragments in examples/crash_reporter/backend/deploy/
S3 Use Docker for PHP-FPM pools only after MariaDB split — avoid double complexity
S4 Keep Gitea on be-ops until mirror count > 10 repos
S5 Document connection pool sizes when RSSH device count > 500
S6 Re-read this DR when SFU SPEC lands — revise §9
S7 Add WAN Mbps graph series on FE before next OTA wide release
S8 Staging test matrix: X-Debug-Country: ZM for geo deny paths

19. Changelog

Date Change
2026-06-12 Initial DR from draft 20100612_1_scaling.txt; options matrix; task graph
2026-06-12 Rev. 2 — bandwidth (§8b), global/GEO (§8c), F10, task graph + open items

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