Diagnose Deployment Failures for Starlette

Deployment diagnostics for a Starlette app on Ample. Verified on Starlette: 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.

Prerequisites

• A Starlette project (pip install into .ample/python from requirements.txt, then uvicorn from run.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 Starlette 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

Success Checks

• Failed deploy reports health_check_failed synchronously
  Expect: ample deploy exits 1 with error.code health_check_failed
• Runtime log carries the app's own error line
  Expect: 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 Starlette 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
    • Monthly Amount: 5.0

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

Examples

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

Evidence Summary

• Kind: canary_run
  Summary: Starlette pattern fixture deployed on Ample with CANARY_FAIL=boot; the cause is read from the framework's output rather than guessed.
  Observed At: 2026-09-21T02:23:07Z
  Implementation Revision: 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty
  Expires At: 2027-03-20T02:23:07Z