deployment diagnostics.md

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 <deployment_id> --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.

Infrastructure requirements

Compute: verified (Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.)

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

Exact tested configuration

template: node-22
runtime: node
size: s-1vcpu-1gb
install: npm install
build: npm run build --if-present
start: npm run start

Steps

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.
Read the build log. The last lines name the failing command and its output.
```
ample logs <deployment_id> --kind build  
```
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 <deployment_id> --kind runtime  
```
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.
Verify. Fetch the live URL on the example; on failure read the build and runtime logs.
```
ample logs <deployment_id> --kind build  
```

Tested examples

Fastify pattern fixture (tests/deploy-canaries/fastify-patterns): Verified deployment diagnostics on Fastify.

Success checks

failed deploy reports health_check_failed synchronously
runtime log carries the app's own error line

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

Estimated 5.00 USD per month (size prices from pricing.toml at build revision a1b8c38919e59cd035ebabaced73cf84ece24371).

app server x1 s-1vcpu-1gb: 5.00 USD

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

Verification evidence

canary_run on 2026-09-21T02:23:07Z at revision 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21): 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 <deployment_id> --kind runtime, so the cause is read from the framework's output rather than guessed. (expires 2027-03-20T02:23:07Z)

Last verified: 2026-09-21T02:23:07Z.