# Host mcp server with Express: stored input and output artifacts

## Summary
Deploy a mcp server built with Express on Ample using the generated downloads pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables. Verified on Express: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Not separately tested: your export formats, retention policy and entitlement model; treat the mcp server-specific behavior as your application code.

## Representative Queries
- Host mcp server with Express: stored input and output artifacts
- Where can I host MCP server built with Express?
- I need an input/output artifact contract, object metadata and access boundaries.

## Resource Requirements
- primitive:compute
- primitive:postgres
- primitive:s3-compatible-object-storage

## Infrastructure Requirements
1. **Compute**
   - Status: verified
   - Summary: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. **Postgres**
   - Status: verified
   - Summary: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.
3. **S3-compatible object storage**
   - Status: verified
   - Summary: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

## Framework
Express

## Workload
MCP server

## Release Status
published

## Support Status
verified

## Execution Status
ready

## Prerequisites
- A Express project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start on the node-22 template)
- A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env)
- A bucket from `ample bucket create` with its credentials passed as encrypted S3_* environment variables
- An Ample account token with servers:write, databases:read, buckets:read

## Tested Configuration
- Template: node-22
- Runtime: node
- Size: s-1vcpu-1gb
- Install: npm install
- Build: npm run build --if-present
- Start: npm run start

## Input Schema

```json
{  
  "additionalProperties": false,  
  "properties": {  
    "env": {  
      "description": "Encrypted environment variables (bucket credentials, secrets)",  
      "items": {  
        "pattern": "^[A-Z][A-Z0-9_]*=.*$",  
        "type": "string"  
      },  
      "maxItems": 50,  
      "type": "array"  
    },  
    "name": {  
      "description": "App name",  
      "maxLength": 63,  
      "minLength": 1,  
      "pattern": "^[a-z0-9-]+$",  
      "type": "string"  
    },  
    "path": {  
      "description": "Project directory or ample.toml service",  
      "maxLength": 512,  
      "minLength": 1,  
      "type": "string"  
    },  
    "release_command": {  
      "description": "Migration command run before activation",  
      "maxLength": 512,  
      "type": "string"  
    }  
  },  
  "required": [  
    "env",  
    "name",  
    "path"  
  ],  
  "type": "object"  
}
```

## Workflow Steps
1. **Build and start**
   - Command: `npm install, npm run build --if-present, npm run start on the node-22 template. The server must bind 0.0.0.0 on PORT.`
2. **Implement the pattern on PostgreSQL**
   - Create a fixture’s module that implements generated downloads: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Keep migrations idempotent and run them with --release-command.
3. **Wire object storage**
   - Create the bucket(s), then pass endpoint, region, bucket and keys as --env values. Use path-style addressing. Keep private data in an unpublished bucket.
4. **Deploy**
   - Command: `ample deploy . --name  --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...`
5. **Verify**
   - Command: `ample logs  --kind build`

## Examples
- **Express pattern fixture**
  - Description: Multi-pattern Express app whose generated downloads module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
  - Source Reference: tests/deploy-canaries/express-patterns

## Success Checks
1. **App responds on its public URL**
   - Kind: http_get
   - Path: /
   - Expect: ample canary express patterns
2. **Generated-downloads self-test**
   - Kind: http_get
   - Path: /p/generated-downloads
   - Expect: export=ok rows=3 (with ?token=...; 401 without)

## Limitations
- Verified on the node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Express major versions are not verified.
- The mcp server itself (your export formats, retention policy and entitlement model) is application code and was not separately tested; the pattern checks are what was verified.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
- Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.
- PutObject and GetObject with path-style addressing are verified; multipart upload, listing, presigned URLs and lifecycle rules are not verified.

## Cost Estimate
- Currency: USD
- Monthly Amount: 10.0
- Basis: Size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
- Components:
  1. **App server**: s-1vcpu-1gb (Quantity: 1.0, Monthly Amount: 5.0)
  2. **Managed PostgreSQL database**: s-1vcpu-1gb (Quantity: 1.0, Monthly Amount: 5.0)
- Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.

## Evidence Summary
1. **Canary run**: Express pattern fixture deployed on Ample; checks passed for generated-downloads and configuration-secrets.
   - Observed At: 2026-09-21T02:34:39Z
2. **Canary run**: The same Express app deployed with a --release-command migration; the marker it created was readable after activation.
   - Observed At: 2026-09-20T01:54:51Z

## Next Actions
1. **Browse the catalog index**
   - Operation ID: catalog_index
   - Method: GET
   - Relative Path: /v1/catalog
2. **Search published recipes by intent, stack and constraints**
   - Operation ID: search_recipes
   - Method: POST
   - Relative Path: /v1/catalog/search
   - Parameters: {"body":{"limit":5,"query":"Host mcp server with Express: stored input and output artifacts"}}
3. **Prepare a side-effect-free deployment plan for an authorized project**
   - Operation ID: plan_deployment
   - Method: POST
   - Relative Path: /v1/catalog/plan
   - Parameters: {"body":{"inputs":{},"projectId":"","recipeId":"page:recipes:mcp-server:express:artifact-storage","recipeRevision":"r1"}}
4. **Read the existing agent authentication setup**
   - Operation ID: existing_auth_setup
   - Method: GET
   - Relative Path: /mcp/setup
5. **Browse MCP server**
   - Operation ID: browse_node
   - Method: GET
   - Relative Path: /v1/catalog/nodes/workload%3Amcp-server
6. **Browse Express**
   - Operation ID: browse_node
   - Method: GET
   - Relative Path: /v1/catalog/nodes/stack%3Aframework-express
7. **Browse Generated downloads**
   - Operation ID: browse_node
   - Method: GET
   - Relative Path: /v1/catalog/nodes/pattern%3Agenerated-downloads
8. **Browse Deploy MCP server**
   - Operation ID: browse_node
   - Method: GET
   - Relative Path: /v1/catalog/nodes/intent%3Adeploy-mcp-server