## The short version

Diagnose a failed Express deployment on Ample. Deploy is synchronous: a build failure returns build_failed with the deployment id, and ample logs exposes the build log and then the runtime log so the cause is read, not guessed.

## INFRASTRUCTURE

### What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)

## PREREQUISITES

### Before you start

- A deployment id from a failed ample deploy
- An Ample account token with servers:read

## STEP BY STEP

### How to do it

1. 1

#### Read the failure code

Exit 1 with build_failed means the isolated build failed; exit 2 means a required preflight action is blocking.

2. 2

#### Read the build log

The last lines name the failing command.
   
   ```
   ample logs <deployment_id> --kind build
   ```

3. 3

#### Read the runtime log

For a live-but-misbehaving app the runtime log shows the process output.
   
   ```
   ample logs <deployment_id> --kind runtime
   ```

4. 4

#### Fix and redeploy once

Change the source or the command override, then run ample deploy again. Do not loop deploys to poll status.

## EXAMPLES

### Tested examples

- **Intentional build failure canary** (`tests/deploy-canaries/node-package-no-lock (build-and-list-failure)`): A failing build command is rejected synchronously and its stderr line appears in the build log.

## SUCCESS CHECKS

### How to know it worked

- build log contains the failing command output

## COST

### Cost estimate

Unknown. No price is claimed for this recipe.

## EVIDENCE

### Verification evidence

- canary_run on 2026-09-19T23:55:33Z at revision `1764076-tls-account-903d345`: An intentionally failing build was rejected synchronously with build_failed and the failure line was readable in the build log. (expires 2027-03-18T23:55:33Z)
- canary_run on 2026-09-19T23:55:33Z at revision `1764076-tls-account-903d345`: Express app with npm install and npm run start deployed on the node-22 template; the public URL served the expected response. (expires 2027-03-18T23:55:33Z)

## EXECUTION

### Execution binding

No execution binding. This recipe is documentation only; nothing is executed automatically.

## NEXT ACTIONS

### Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse Express (`GET /v1/catalog/nodes/stack%3Aframework-express` on the api origin; authentication not required, approval not required)
- Browse Troubleshoot deployment (`GET /v1/catalog/nodes/intent%3Atroubleshoot-deployment` on the api origin; authentication not required, approval not required)
- Browse Public web service (`GET /v1/catalog/nodes/pattern%3Apublic-web-service` on the api origin; authentication not required, approval not required)

Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.

## ABOUT THIS RECIPE

### Identifiers and status

Recipe `page:guides:express:deployment-diagnostics`. Revision r1.

release **published** support **verified** execution **unbound**

Formats: [HTML](/content/guides/express/deployment-diagnostics/index.html) | [Markdown](/content/guides/express/deployment-diagnostics.md) | [JSON contract](https://api.ample.computer/v1/catalog/recipes/page%3Aguides%3Aexpress%3Adeployment-diagnostics)