page:guides:fastify:deployment diagnostics

Diagnose deployment failures for Fastify

Summary

Deployment diagnostics for a Fastify app on Ample. Verified on Fastify: 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: npm install, npm run build --if-present, npm run start on the node-22 template.

Prerequisites

• A Fastify project (npm install, npm run build --if-present, npm run start on the node-22 template)
• An Ample account token with servers:write

Resource Requirements

• Primitive: Compute

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.

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.

   ample logs  --kind build
   

3. Read the runtime log
   For health_check_failed the runtime log carries the Fastify 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.

   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.

   ample logs  --kind build
   

Examples

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

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 node-22 template at s-1vcpu-1gb; other sizes and Fastify major versions are not verified.
• Region, compliance attestations and request-duration limits are unknown and not claimed.

Cost Estimate

• Currency: USD
• Monthly Amount: 5.00
• Basis: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  • App Server: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: 5.00
• Note: Always-on monthly price of the tested sizes; apps auto-pause when idle.

Evidence Summary

• Kind: Canary run
  Summary: Fastify pattern fixture deployed on Ample with CANARY_FAIL=boot (npm install, npm run build --if-present, npm run start on the node-22 template); 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.
• Observed At: 2026-09-21T02:23:07Z
• Expires At: 2027-03-20T02:23:07Z

Next Actions

• Browse the catalog index: GET /v1/catalog
• Search published recipes by intent, stack and constraints: POST /v1/catalog/search
  Request Body: {"limit":5,"query":"Diagnose deployment failures for Fastify"}
• Prepare a side-effect-free deployment plan for an authorized project: POST /v1/catalog/plan
  Request Body: { "inputs":{}, "projectId":"", "recipeId":"page:guides:fastify:deployment-diagnostics", "recipeRevision":"r1" }
• Read the existing agent authentication setup: GET /mcp/setup