Host asset library with Spring Boot: file attachments

Deploy an asset library built with Spring Boot on Ample using the browser file uploads 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 Spring Boot: content-type and size validation that rejects disallowed files, an object written to a private bucket and a row linking the record to the object key (reject=ok upload=ok linked=ok). Not separately tested: your upload UI, allowed types, size limits and virus scanning; treat the asset library-specific behavior as your application code.

Representative Queries

• Host asset library with Spring Boot: file attachments
• Where can I host Asset library built with Spring Boot?
• I need a restricted upload flow, file validation and record-to-object linkage.

Resource Requirements

• primitive:compute
• primitive:postgres
• primitive:s3-compatible-object-storage

Infrastructure Requirements

1. Compute
   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
   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
   Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

Prerequisites

• A Spring Boot project that builds and starts with the documented commands (./mvnw -q -DskipTests package (or the Gradle wrapper) producing one application jar, then java -jar on the jvm-21 template (Temurin JDK 21) with server.port read from PORT)
• 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

Workflow Steps

1. Build and start
   ./mvnw -q -DskipTests package (or the Gradle wrapper) producing one application jar, then java -jar on the jvm-21 template (Temurin JDK 21) with server.port read from PORT. The server must bind 0.0.0.0 on PORT.
2. Implement the pattern on PostgreSQL
   The fixture's module implements browser file uploads: content-type and size validation that rejects disallowed files, an object written to a private bucket and a row linking the record to the object key (reject=ok upload=ok linked=ok). Copy the approach into your schema; 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
   Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op. 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
   Fetch the live URL and the pattern self-test route(s) (/p/browser-file-uploads) from the example; then run your own checks. On failure read ample logs --kind build then --kind runtime.
   Command: ample logs --kind build

Success Checks

• App responds on its public URL
• Browser-file-uploads self-test

Limitations

• Verified on the jvm-21 template at s-1vcpu-2gb with the example fixture; other sizes, templates and Spring Boot major versions are not verified.
• The asset library itself (your upload UI, allowed types, size limits and virus scanning) 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

• Monthly Amount: 10.0 USD
  • Components
    • App server (s-1vcpu-1gb): $5.00
    • Managed PostgreSQL database (s-1vcpu-1gb): $5.00
  • 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.

Example

Spring Boot pattern fixture

Multi-pattern Spring Boot app whose browser file uploads module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

Next Actions

• Browse the catalog index
  Method: GET
  Relative Path: /v1/catalog

• Search published recipes by intent, stack and constraints
  Method: POST
  Relative Path: /v1/catalog/search
  Body: {"limit":5,"query":"Host asset library with Spring Boot: file attachments"}

• Prepare a side-effect-free deployment plan for an authorized project
  Method: POST
  Relative Path: /v1/catalog/plan
  Body: {"inputs":{},"projectId":"","recipeId":"page:recipes:asset-library:spring-boot:attachments","recipeRevision":"r1"}

• Read the existing agent authentication setup
  Method: GET
  Relative Path: /mcp/setup

• Browse Asset library
  Method: GET
  Relative Path: /v1/catalog/nodes/workload%3Aasset-library
  NodeId: workload:asset-library

• Browse Spring Boot
  Method: GET
  Relative Path: /v1/catalog/nodes/stack%3Aframework-spring-boot
  NodeId: stack:framework-spring-boot

• Browse Browser file uploads
  Method: GET
  Relative Path: /v1/catalog/nodes/pattern%3Abrowser-file-uploads
  NodeId: pattern:browser-file-uploads

• Browse Deploy web app
  Method: GET
  Relative Path: /v1/catalog/nodes/intent%3Adeploy-web-app
  NodeId: intent:deploy-web-app