78 lines
2.4 KiB
Markdown
78 lines
2.4 KiB
Markdown
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# Architecture
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Messenger is a self-hosted monolith: a single Go binary serves the REST API,
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WebSocket hub, media files and the built frontend. PostgreSQL is the only
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stateful dependency; attachments live on local disk behind an S3-like
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interface.
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## Component diagram
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```mermaid
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flowchart LR
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subgraph Browser[Browser / PWA]
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UI[React + Vite + Tailwind]
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SW[Service Worker<br/>offline cache + Web Push]
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end
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subgraph Server[Go binary - single process]
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HTTP[REST API /api/v1]
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WS[WebSocket hub<br/>in-memory]
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MEDIA[Media service<br/>thumbnails]
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PUSH[Push notifier<br/>VAPID]
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end
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subgraph Data
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PG[(PostgreSQL 17)]
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DISK[(local disk<br/>S3-like Storage)]
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end
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UI -->|REST + WS| HTTP
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UI --> WS
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SW -->|Web Push| PUSH
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HTTP --> PG
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WS --> PG
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PUSH --> PG
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MEDIA --> DISK
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HTTP --> MEDIA
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WS -.->|presence check| PUSH
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```
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## Request flow for a message
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```mermaid
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sequenceDiagram
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participant A as Alice (PWA)
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participant API as API
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participant PG as PostgreSQL
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participant WS as WS hub
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participant B as Bob (PWA)
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A->>API: POST /conversations/{id}/messages
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API->>PG: INSERT message
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API->>WS: publish message.created
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WS-->>A: message.created (echo)
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WS-->>B: message.created
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API->>PUSH: notify offline members
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PUSH-->>B: Web Push (if offline)
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API-->>A: 201 message
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```
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## Key decisions (see docs/adr)
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| Area | Decision | Rationale |
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|---|---|---|
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| Shape | Monolith, one container | Family scale; trivial deploy; no fake microservices |
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| Realtime | In-memory WS hub | Presence and delivery in one process; pg LISTEN/NOTIFY is the scaling path |
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| Search | ILIKE substring | No extension dependency; instant at family scale; pg_trgm noted as upgrade |
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| Media | S3-like Storage interface | Swap local disk for MinIO without touching handlers |
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| Auth | JWT access + rotated refresh in httpOnly cookies | No token in JS; rotation limits replay |
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| Crypto | TLS in transit; E2EE via libsignal on roadmap | Never hand-roll crypto |
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## Deployment
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docker-compose runs: api, postgres, victoriametrics, grafana.
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See `deploy/` for compose + Grafana dashboard provisioning.
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- **Metrics**: `GET /metrics` (Prometheus format), scraped by VictoriaMetrics
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- **Grafana**: http://localhost:3000, dashboard «Messenger» auto-provisioned
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- **Push**: optional; requires VAPID keys (`go run ./cmd/keygen`)
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