page:recipes:mobile backend:flask:artifact storage

Host mobile backend with Flask: stored input and output artifacts

Deploy a mobile backend built with Flask 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 Flask: 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 mobile backend-specific behavior as your application code.

Representative Queries

Resource Requirements

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.
    • Compute Documentation

  2. Postgres

    • Status: verified
    • Summary: Managed PostgreSQL 16 runs in its own microVM when an app needs a database and no DATABASE_URL is supplied.
    • Postgres Documentation

  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.
    • S3 Documentation

Prerequisites

Workflow Steps

  1. Build and start

    • pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 template. The server must bind 0.0.0.0 on PORT.

  2. Implement the pattern on PostgreSQL

    • The fixture's module 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). 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 Keep private data in an unpublished bucket.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 --start "python3 app.py" --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/generated-downloads) from the example; then run your own checks. On failure read ample logs --kind build then --kind runtime.
    • Command: ample logs --kind build

Tested Configuration

Limitations

  1. Verified on the python-3.12 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Flask major versions are not verified.
  2. The mobile backend itself (your export formats, retention policy and entitlement model) is application code and was not separately tested; the pattern checks are what was verified.
  3. Region, compliance attestations and request-duration limits are unknown and not claimed.
  4. Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
  5. Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.
  6. PutObject and GetObject with path-style addressing are verified; multipart upload, listing, presigned URLs and lifecycle rules are not.

Next Actions