Diagnose deployment failures for Phoenix | Ample
INFRASTRUCTURE
What it needs
- 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
Before you start
- A Phoenix project (mix deps.get, MIX_ENV=prod mix compile and mix release in the builder, then the release bin script with PHX_SERVER=true on the elixir-1.18 template; PORT, DATABASE_URL and SECRET_KEY_BASE read in config/runtime.exs)
- An Ample account token with servers:write
TESTED CONFIGURATION
Exactly what was tested
- build:
MIX_ENV=prod mix compile && MIX_ENV=prod mix release --overwrite - install:
mix local.hex --force && mix local.rebar --force && MIX_ENV=prod mix deps.get --only prod - runtime:
elixir - size:
s-1vcpu-1gb - start:
PHX_SERVER=true _build/prod/rel/$(ls _build/prod/rel | head -n 1)/bin/$(ls _build/prod/rel | head -n 1) start - template:
elixir-1.18
STEP BY STEP
How to do it
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 <deployment_id> --kind build3
Read the runtime log
For health_check_failed the runtime log carries the Phoenix 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 runtime4
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 <deployment_id> --kind build
EXAMPLES
Tested examples
- Phoenix pattern fixture (
tests/deploy-canaries/phoenix-patterns): Verified deployment diagnostics on Phoenix.
SUCCESS CHECKS
How to know it worked
- failed deploy reports health_check_failed synchronously
- runtime log carries the app's own error line
LIMITATIONS
Know the limits
- Verified on the elixir-1.18 template at s-1vcpu-1gb; other sizes and Phoenix major versions are not verified.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
COST
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.
EVIDENCE
Verification evidence
- canary_run on 2026-09-21T03:06:43Z at revision
49962bc-dirty (CLI 0.1.21): Phoenix pattern fixture deployed on Ample with CANARY_FAIL=boot (mix deps.get, MIX_ENV=prod mix compile and mix release in the builder, then the release bin script with PHX_SERVER=true on the elixir-1.18 template; PORT, DATABASE_URL and SECRET_KEY_BASE read in config/runtime.exs); the same app deployed with a deliberate boot failure (CANARY_FAIL=boot):ample deployexited 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 withample logs <deployment_id> --kind runtime, so the cause is read from the framework's output rather than guessed. (expires 2027-03-20T03:06:43Z)
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/catalogon the api origin; authentication not required, approval not required) - Search published recipes by intent, stack and constraints (
POST /v1/catalog/searchon the api origin; authentication not required, approval not required) - Prepare a side-effect-free deployment plan for an authorized project (
POST /v1/catalog/planon the api origin; authentication required, approval not required) - Read the existing agent authentication setup (
GET /mcp/setupon the api origin; authentication not required, approval not required) - Browse Phoenix (
GET /v1/catalog/nodes/stack%3Aframework-phoenixon the api origin; authentication not required, approval not required) - Browse Troubleshoot deployment (
GET /v1/catalog/nodes/intent%3Atroubleshoot-deploymenton the api origin; authentication not required, approval not required) - Browse Public web service (
GET /v1/catalog/nodes/pattern%3Apublic-web-serviceon 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.