Diagnose Deployment Failures for Flask

Summary

Deployment diagnostics for a Flask app on Ample. Verified on Flask: the same app deployed with a deliberate boot failure (CANARY_FAIL=boot): ample deploy exited 1 with a coded failure (health_check_failed when the process dies at boot, public_ingress_failed when the framework boots but every request answers 500) and the app's own error line was readable with ample logs --kind runtime, so the cause is read from the framework's output rather than guessed. Build and start: pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 template.

Prerequisites

• A Flask project (pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 template)
• An Ample account token with servers:write

Workflow Steps

1. Read the failure code
   Deploy is synchronous. Exit 1 with build_failed means the isolated build failed; health_check_failed means the app built but never answered on PORT (it crashed at boot or bound the wrong port); public_ingress_failed means it answered on PORT but the public URL returned an error status (a request handler or bootstrap failed); exit 2 means a required preflight action is blocking.

2. Read the build log
   The last lines name the failing command and its output.
   Command: ample logs --kind build

3. Read the runtime log
   For health_check_failed the runtime log carries the Flask process output: in the verified run the deliberate boot failure's own error line was there, followed by the platform's health-check verdict and the start command it ran.
   Command: ample logs --kind runtime

4. Fix and redeploy once
   Change the source, the environment or the command override, then run ample deploy again. Do not loop deploys to poll status; an unchanged redeploy is a no-op.

5. Verify
   Fetch the live URL on the example; on failure read the build and runtime logs.
   Command: ample logs --kind build

Examples

• Flask pattern fixture: Verified deployment diagnostics on Flask.
  Source Reference: tests/deploy-canaries/flask-patterns

Success Checks

• Check if failed deploy reports health_check_failed synchronously:
  Expectation: ample deploy exits 1 with error.code health_check_failed

• Check if runtime log carries the app's own error line:
  Expectation: ample logs --kind runtime shows the framework's error output before the health-check verdict.

Limitations

• Verified on the python-3.12 template at s-1vcpu-1gb; other sizes and Flask major versions are not verified.
• Region, compliance attestations and request-duration limits are unknown and not claimed.

Cost Estimate

• Currency: USD
• Monthly Amount: 5.0
• Basis: Size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  • app server, size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0

Note: Always-on monthly price of the tested sizes; apps auto-pause when idle. Buckets are allocation-priced per quota and not included.

Evidence Summary

• Canary Run: Flask pattern fixture deployed on Ample with CANARY_FAIL=boot. Observed at: 2026-09-21T02:23:07Z

Last Verified At

2026-09-21T02:23:07Z