{"id":"69bb38f53f1c7d8bc1820a09","title":"Current Architecture","path":"how-to/technical-articles/2026-03-18-single-instance-multi-tenant-exploration/current-architecture","contentMarkdown":"# Current Architecture: Per-Group Deployment Model\n\n_____\n\nThe current NGX Ramblers architecture deploys a single Docker image to multiple independent Fly.io apps. Each app connects to its own MongoDB database and S3 bucket, providing complete data isolation.\n\n## Architecture Diagram\n\n```mermaid\nflowchart TD\n IMG@{ icon: \"logos:docker-icon\", label: \"Single Docker Image\", pos: \"b\", h: 48 }\n\n IMG --> APP1@{ icon: \"logos:fly-icon\", label: \"Group A (512MB)\", pos: \"b\", h: 48 }\n IMG --> APP2@{ icon: \"logos:fly-icon\", label: \"Group B (512MB)\", pos: \"b\", h: 48 }\n IMG --> APP3@{ icon: \"logos:fly-icon\", label: \"Group C (512MB)\", pos: \"b\", h: 48 }\n IMG --> APPN[\"... x 13 apps\"]\n\n APP1 --> DB1@{ icon: \"ngx:mongodb\", label: \"Group A DB\", pos: \"b\", h: 48 }\n APP2 --> DB2@{ icon: \"ngx:mongodb\", label: \"Group B DB\", pos: \"b\", h: 48 }\n APP3 --> DB3@{ icon: \"ngx:mongodb\", label: \"Group C DB\", pos: \"b\", h: 48 }\n\n APP1 --> S31@{ icon: \"ngx:aws\", label: \"Group A bucket\", pos: \"b\", h: 48 }\n APP2 --> S32@{ icon: \"ngx:aws\", label: \"Group B bucket\", pos: \"b\", h: 48 }\n APP3 --> S33@{ icon: \"ngx:aws\", label: \"Group C bucket\", pos: \"b\", h: 48 }\n```\n\n## Key Characteristics\n\n- **13 separate Fly.io apps**, each with 512MB–1GB memory\n- **One MongoDB database per group** (complete data isolation)\n- **One S3 bucket per group** (separate image/file storage)\n- **One AUTH_SECRET per group** (independent JWT signing)\n- **One Cloudflare subdomain per group** (e.g. `group-a.ngx-ramblers.org.uk`)\n- Groups also have custom domains (e.g. `group-a-ramblers.org.uk`)\n- The Angular frontend is identical across all sites — all site-specific behaviour comes from runtime config loaded from the database\n\n## What Already Works\n\n| Capability | Status |\n|------------|--------|\n| Single codebase | One repo, one team |\n| Single build artifact | One Docker image for all sites |\n| Automated group provisioning | CLI tool creates new groups end-to-end |\n| Per-group custom domains | Each group has its own domain and branding |\n| Complete data isolation | Physically separate databases — no cross-group leakage possible |\n\n## Strengths of This Model\n\n- **Data isolation is inherent** — no risk of cross-group data leakage because databases are physically separate\n- **Blast radius is limited** — a bug or outage on one group's app doesn't affect others\n- **Resource isolation** — one group's heavy traffic doesn't starve others\n- **Simple application code** — no tenant context needed in queries, middleware, or auth\n","contentHtml":"

Current Architecture: Per-Group Deployment Model

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The current NGX Ramblers architecture deploys a single Docker image to multiple independent Fly.io apps. Each app connects to its own MongoDB database and S3 bucket, providing complete data isolation.

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Architecture Diagram

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flowchart TD\n    IMG@{ icon: "logos:docker-icon", label: "Single Docker Image", pos: "b", h: 48 }\n\n    IMG --> APP1@{ icon: "logos:fly-icon", label: "Group A (512MB)", pos: "b", h: 48 }\n    IMG --> APP2@{ icon: "logos:fly-icon", label: "Group B (512MB)", pos: "b", h: 48 }\n    IMG --> APP3@{ icon: "logos:fly-icon", label: "Group C (512MB)", pos: "b", h: 48 }\n    IMG --> APPN["... x 13 apps"]\n\n    APP1 --> DB1@{ icon: "ngx:mongodb", label: "Group A DB", pos: "b", h: 48 }\n    APP2 --> DB2@{ icon: "ngx:mongodb", label: "Group B DB", pos: "b", h: 48 }\n    APP3 --> DB3@{ icon: "ngx:mongodb", label: "Group C DB", pos: "b", h: 48 }\n\n    APP1 --> S31@{ icon: "ngx:aws", label: "Group A bucket", pos: "b", h: 48 }\n    APP2 --> S32@{ icon: "ngx:aws", label: "Group B bucket", pos: "b", h: 48 }\n    APP3 --> S33@{ icon: "ngx:aws", label: "Group C bucket", pos: "b", h: 48 }\n
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Key Characteristics

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What Already Works

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CapabilityStatus
Single codebaseOne repo, one team
Single build artifactOne Docker image for all sites
Automated group provisioningCLI tool creates new groups end-to-end
Per-group custom domainsEach group has its own domain and branding
Complete data isolationPhysically separate databases — no cross-group leakage possible
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Strengths of This Model

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