smackerel-no-defaults

Smackerel NO-DEFAULTS Guard

Goal

Prevent silent runtime fallback config. Smackerel must fail loudly when required config is missing so agents and operators cannot accidentally ship hidden defaults.

This skill covers Smackerel's generic repo-owned configuration and deployment contracts. Final host configuration for a concrete self-hosted, cloud VM, or other deployment target belongs in an operator-private deploy-adapter overlay, not in this repo.

Use This Skill When

• Editing config/smackerel.yaml, scripts/commands/config.sh, docker-compose.yml, deploy/compose.deploy.yml, or deploy adapter logic.
• Changing docs, instructions, or skills that describe config, env vars, ports, host bind addresses, or deployment.
• Reviewing any use of shell/Compose interpolation, os.getenv, process.env, or config helper defaults.
• Touching HOST_BIND_ADDRESS, port mappings, env files, or Build-Once Deploy-Many config bundles.

Blocking Rules

• No ${VAR:-default} or ${VAR-default} for SST-managed runtime values.
• No language-level fallback for required config (os.getenv("KEY", "default"), process.env.KEY || "default", unwrap_or(...)).
• No docs language that implies an implicit fallback (safe-by-default, loopback default, preserves loopback).
• No generated config edits by hand.
• No deploy adapter may rely on Compose to invent missing values.

Required Patterns

Surface	Required Pattern
Compose / shell required value	${VAR:?clear error message}
Go required env	os.Getenv("KEY") plus explicit empty-value error
Python required env	os.environ["KEY"] or explicit empty-value error
TypeScript required env	process.env.KEY plus explicit missing-value throw
Loopback bind	Explicit HOST_BIND_ADDRESS=127.0.0.1 in generated/apply-time env, never a Compose fallback

HOST_BIND_ADDRESS Contract

The live deploy bind-address contract is:

ports:
  - "${HOST_BIND_ADDRESS:?HOST_BIND_ADDRESS must be set by deploy adapter}:${CORE_HOST_PORT}:${CORE_CONTAINER_PORT}"

The deploy adapter must write HOST_BIND_ADDRESS explicitly into app.env before Compose starts. If it cannot determine the bind address, it must fail before docker compose up. 127.0.0.1 is valid only as an explicit configured value.

Review Checklist

[ ] Touched files contain no hidden fallback for required runtime config.
[ ] Any mention of `${VAR:-default}` labels it as forbidden, not recommended.
[ ] `HOST_BIND_ADDRESS` docs say adapter-set explicit value + fail-loud Compose.
[ ] `deploy/compose.deploy.yml` and `internal/deploy/compose_contract_test.go` match.
[ ] Validation evidence uses repo-standard commands from `.github/copilot-instructions.md`.

Anti-Patterns

Anti-Pattern	Why It Blocks	Fix
${HOST_BIND_ADDRESS:-127.0.0.1} in live Compose	Missing adapter config silently becomes loopback	${HOST_BIND_ADDRESS:?HOST_BIND_ADDRESS must be set by deploy adapter}
"loopback default" in docs	Teaches agents to rely on fallback behavior	"explicit loopback value"
os.getenv("SMACKEREL_AUTH_TOKEN", "") for required config	Auth misconfig becomes empty string	Required env read plus explicit empty check
Adapter omits HOST_BIND_ADDRESS because Compose has a fallback	Adapter contract is incomplete	Adapter writes the value or fails before Compose