cloud-sync/DESIGN.md

cloud-sync — design

Per-Discord-user state sync for Minecraft. Pulls on launch, pushes on exit. Single JAR drops into Prism / MMC / ATLauncher / frazclient as a pre-launch + post-exit hook.

Data plane: restic-rest-server with --private-repos --append-only. Clients hit this directly with their per-user password.

Control plane: cloud-svc Go service with two listeners — a provisioning port reachable from automc-net (called by discord-bot) and a loopback admin port (called by automc-setup wizard). Players never touch cloud-svc.

Client: cloud-sync.jar subprocesses restic. ~200 LOC.

Why this shape

Concern	How restic solves it
Snapshot semantics	Native — every restic backup is a snapshot
Deduplication	Chunk-level (not just file-level), built in
Retention policy	restic forget --keep-last/daily/weekly/monthly
Append-only enforcement	restic-rest-server --append-only: even with a valid password, clients can't delete
Per-user isolation	--private-repos: URL path must contain the authenticated username
Encryption at rest	Per-repo password, built in
Multi-machine support	Restic tags + hostname; if we ever want it, free

cloud-svc as originally designed was a worse re-implementation of all the above. Pivoting before it ships; cloud-svc gets reshaped into the control plane described below.

Topology

flowchart LR
    pl["player PC"]:::external
    op["operator
(via SSH)"]:::external
    jar["cloud-sync.jar
(in launcher's
pre/post hooks)"]:::deploy
    restic["restic binary
(auto-downloaded
on first run)"]:::deploy

    subgraph john["john (192.168.65.33)"]
        rp{{"reverse proxy
:443"}}:::deploy

        subgraph net["automc-net"]
            ao{{"restic-rest-server
--private-repos
--append-only
:8002"}}:::deploy
            bot{{"discord-bot"}}:::deploy
            cs_int{{"cloud-svc
provisioning :9091
(automc-net only)"}}:::deploy
        end

        cs_admin{{"cloud-svc
admin :9092
(127.0.0.1 only)"}}:::deploy

        store[/"/srv/cloud-data
/<discord_id>/..."/]:::pvc
        htp[/"/etc/restic-users
htpasswd"/]:::pvc
    end

    pl --> jar --> restic
    restic ==>|"rest:https
<discord_id>:<password>"| rp
    rp -->|"loopback"| ao
    ao -->|"reads"| htp
    ao -->|"writes"| store

    bot -.->|"on /register:
POST /admin/users"| cs_int
    cs_int -.->|"htpasswd add
restic init
key add"| htp
    cs_int -.->|"mints repo"| store
    bot -.->|"DM password"| pl

    op -.->|"SSH then
automc-setup cloud ..."| cs_admin
    cs_admin -.->|"list / prune / revoke"| htp
    cs_admin -.->|"prune via
operator master key"| store

    classDef deploy fill:#d5e8d4,stroke:#82b366,color:#000
    classDef pvc fill:#f5f5f5,stroke:#666,color:#000
    classDef external fill:#f5f5f5,stroke:#666,color:#000,stroke-dasharray:5 5

cloud-svc runs as one process with two listeners:

Listener	Bind	Reachable from	Endpoints
Provisioning	automc-net:9091 (no PublishPort)	discord-bot via service-net DNS	POST /admin/users only
Operator	127.0.0.1:9092	john's loopback (SSH session)	GET/DELETE /admin/users, POST /admin/users/{id}/prune, GET /admin/users/{id}/quota, etc.

The split means a compromised discord-bot can mint new accounts but cannot enumerate, prune, or revoke existing ones. Operator-only ops require shell access on john.

Auth model:

• Provisioning listener: shared service token (env CLOUD_PROVISIONING_KEY), discord-bot uses same value from its own env
• Operator listener: no auth — loopback bind is the boundary, same pattern as server-manager:127.0.0.1:8080

Auth & identity

Element	Value
User identity	Discord ID (immutable, from discord-bot's existing account-card flow)
User credential	restic repo password = bcrypt'd in /etc/restic-users htpasswd file
URL pattern	rest:https://cloud.tm.center/<discord_id>/
Server isolation	--private-repos enforces URL path matches authenticated user

discord-bot's /register flow extends to call POST cloud-svc:9091/admin/users with the player's Discord ID. cloud-svc mints a random password, htpasswd -B-adds it to the file, runs restic init + restic key add operator-master, and returns the password. discord-bot DMs it to the player. discord-bot itself never touches restic or htpasswd directly.

Revocation = operator runs automc-setup cloud revoke <discord_id> which hits the loopback admin port. No token store, no scope checks, no auth-service involvement.

Client flow

cloud-sync.jar pull

1. Load creds from <pack-folder>/.cloud-token  (format: discord_id:password on one line)
2. Locate or auto-download restic binary into <jar dir>/restic-<version>/
3. restic -r rest:https://<url>/<discord_id>/ snapshots --latest 1 --json
4. If no snapshots → exit 0 (first run on this machine, nothing to restore)
5. restic restore latest --target <pack-folder> --include-from cloud-scope.txt

cloud-sync.jar push

1. Same creds + restic locator as pull
2. restic backup <pack-folder> --files-from cloud-scope.txt --exclude-from cloud-exclude.txt
3. restic forget --keep-last 20 --keep-daily 7 --keep-weekly 4 --keep-monthly 6 --prune

The forget --prune step is allowed by restic-rest-server --append-only only if the client supplies Force-Allow-Forget: true. We DON'T enable this in --append-only mode — the server refuses forget. Pruning happens server-side via a nightly cron running restic forget with the operator's full-access password against the repo. Clients can only add, never remove.

cloud-scope.json → restic args

Input	Becomes
include: ["options.txt", "config/", "journeymap/data/"]	Listed in cloud-scope.txt, passed as --files-from cloud-scope.txt
exclude: ["config/simple-mod-sync*", "**/*.log"]	Listed in cloud-exclude.txt, passed as --exclude-from cloud-exclude.txt
max_size_mb_per_file: 50	restic doesn't have a per-file size cap; we filter during scope generation

Retention policy

Server-side cron (e.g., daily at 04:00 UTC) walks all per-user repos:

for repo in /srv/cloud-data/*/; do
    user=$(basename "$repo")
    restic -r "$repo" --password-file /etc/restic-master-pass \
        forget --keep-last=20 --keep-daily=7 --keep-weekly=4 --keep-monthly=6 --prune
done

This requires the operator to have a "master password" that opens any user's repo — restic doesn't have that natively. Options:

1. Init each user's repo with TWO keys — one for the user, one for the operator-side pruner. restic supports multi-key per repo.
2. Run the cron with each user's own password — requires storing all user passwords server-side; defeats the encryption.
3. Don't auto-prune — let users push forever, trust quota at the rest-server level.

Recommendation: option 1 (multi-key per repo). On /register, the bot calls restic -r <repo> --password-file <operator> key add to add the player's password as a SECOND key. The pruner cron uses the operator master password.

What's in v1

• restic-rest-server with --private-repos --append-only --htpasswd-file
• discord-bot /register extension: mint password, htpasswd add, restic init repo, restic key add player key
• cloud-sync.jar that subprocesses restic for pull/push
• Auto-download restic binary on first run from upstream GitHub release
• Server-side nightly prune cron with operator-side master password key

What's deferred

• restic version pinning / auto-update of the binary (treat like packwiz-installer self-update)
• Server-side restic check cron for repo integrity
• Per-user quota at the rest-server level (rest-server supports --max-size per-user via .maxsize file in each repo)
• Operator UI for "this player has 25 GB of cloud data, what's in it?"
• Cross-machine sync UX (you can play on PC A then PC B; latest snapshot wins. No conflict UI because restic doesn't merge — restore-latest is destructive by design.)

cloud-svc — reshape, not delete

cloud-svc gets a new purpose: control plane for the restic backend. Throw away:

• Manifest types + validation (manifest.go)
• Blob storage + tarball extraction (storage.go body)
• Player-facing /v1/* endpoints (server.go body)
• Snapshot ID generation, content hash cross-check

Keep:

• Project skeleton (go.mod, Dockerfile, Makefile, CI)
• Auth-cache pattern from auth.go (reused for provisioning token verification)
• Per-user mutex pattern from storage.go (still needed to serialize concurrent provisioning calls)
• Config loader from config.go (adds new vars)

New code:

• Two http.Server instances, one per listener
• htpasswd writer that respects bcrypt + file locking
• restic CLI subprocesser (init repo, add key, prune)
• time.Ticker for nightly prune job

Estimate: ~300 LOC kept, ~600 LOC new. Net smaller than current cloud-svc.

Also delete cloud_pull / cloud_push from frazclient/client.py (these get obsoleted by cloud-sync.jar calls).

Topology consequences for automc/docs/network-exposure.md

Layer	Bind	Public?
restic-ao (data plane)	127.0.0.1:8002	Via reverse proxy at cloud.tm.center:443
cloud-svc provisioning listener	automc-net:9091 (no PublishPort)	No
cloud-svc admin listener	127.0.0.1:9092	No

Only one public HTTPS endpoint changes from the original plan: it now fronts restic-ao instead of cloud-svc. Same reverse-proxy hardening checklist applies. Threat surface differences:

Old (cloud-svc as data path)	New (restic-ao as data path)
Bearer token via auth-service /auth/verify-key	HTTP Basic via htpasswd in restic-rest-server
Custom Go service, 33 tests	Upstream restic-rest-server, well-audited
Player-facing endpoints	None — cloud-svc not public

Operator endpoints are loopback-only and require SSH access to john to reach. No new public surface from the control plane.

Repo layout post-pivot

Repo	Purpose
Timemachine/cloud-sync (this)	Kotlin/Gradle JAR that subprocesses restic
Timemachine/cloud-svc	Reshaped — control plane only. Two-port Go service for provisioning + operator ops. NOT archived.
Timemachine/discord-bot	Extended /register flow calls cloud-svc to provision; DMs returned password
Timemachine/automc	setup wizard adds automc-setup cloud {list,prune,revoke,quota} subcommands hitting cloud-svc's loopback admin port. Quadlet templates for both restic-ao (new flags) and cloud-svc (two listeners). database/schema.sql unchanged.

Pre-implementation checklist

• User reviews this design doc
• Confirmed (2026-06-02): cloud-svc reshapes to control plane, not archived
• Confirmed (2026-06-02): two-port split — automc-net for provisioning, loopback for operator
• Confirm: server-side prune via operator master password key on each repo
• Confirm: cloud-sync.jar auto-downloads restic binary vs requires it pre-installed
• Confirm: nightly prune cadence (default proposal: daily 04:00 UTC)
• Confirm: shared service token between discord-bot and cloud-svc provisioning port (env var on both)