### Host approval workflow with Flask: downloadable reports

**Summary:** Deploy a approval workflow 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 approval workflow-specific behavior as your application code.

### Representative Queries
- Host approval workflow with Flask: downloadable reports
- Where can I host Approval workflow built with Flask?
- I need an export query, generated artifact retention and authorized download flow.

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

### Infrastructure Requirements  
- **Compute:** Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.  
- **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.  
- **S3-compatible object storage:** Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

### Framework  
Flask

### Workload  
Approval workflow

### Release Status  
Published

### Support Status  
Verified

### Execution Status  
Ready

### Prerequisites
- A Flask project that builds and starts with the documented commands (pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 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:** python-3.12  
- **Runtime:** python  
- **Size:** s-1vcpu-1gb  
- **Install:** python3 -m pip install --target .ample/python -r requirements.txt  
- **Start:** PYTHONPATH=.ample/python:${PYTHONPATH:-} python3 app.py

### 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**
   - 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.
4. **Deploy**
   - Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked).
5. **Verify**
   - Fetch the live URL and the pattern self-test route(s) (/p/generated-downloads) from the example; then run your own checks.

### Examples
- **Flask pattern fixture:** Multi-pattern Flask app whose generated downloads module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

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

### Limitations
- 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.

### Cost Estimate
**Monthly Amount:** 10.0 USD 
- **App server:** s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0  
- **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
- **Canary run:** Flask pattern fixture deployed on Ample; checks passed for generated-downloads and configuration-secrets.

### Formats
- [HTML](/content/recipes/approval-workflow/flask/report-exports/index.html)  
- [Markdown](/content/recipes/approval-workflow/flask/report-exports.md)  
- [JSON](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Aapproval-workflow%3Aflask%3Areport-exports)

### Next Actions
- **Browse the catalog index**  
- **Search published recipes by intent, stack and constraints**  
- **Prepare a side-effect-free deployment plan for an authorized project**  
- **Read the existing agent authentication setup**  
- **Browse Approval workflow**  
- **Browse Flask**  
- **Browse Generated downloads**  
- **Browse Deploy web app**