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devopshigh PriorityID: docker-compose-v2-healthcheck-depends

Docker Compose v2 service_healthy Dependency Orchestration Standard

Production standard for multi-container orchestration in Docker Compose v2. Mandates using depends_on with condition: service_healthy instead of naive string list dependencies, preventing application containers from crashing upon startup while waiting for PostgreSQL or Redis readiness.

Prohibited Anti-Pattern: AI writes depends_on: ['db'] without healthchecks, causing backend containers to crash immediately because the database container has started but cannot yet accept connections.

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---
description: Docker Compose v2 service_healthy Dependency Orchestration Standard - Production standard for multi-container orchestration in Docker Compose v2. Mandates using depends_on with condition: service_healthy instead of naive string list dependencies, preventing application containers from crashing upon startup while waiting for PostgreSQL or Redis readiness.
globs: **/docker-compose*.yml, **/docker-compose*.yaml, **/compose.yaml
alwaysApply: false
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/docker-compose-v2-healthcheck-depends"
---

# Docker Compose v2 service_healthy Dependency Orchestration Standard

> **Severity**: HIGH | **Category**: devops
> **Anti-Pattern Warning**: AI writes depends_on: ['db'] without healthchecks, causing backend containers to crash immediately because the database container has started but cannot yet accept connections.

## System Constraints
You are a Container Orchestration Specialist. In Docker Compose v2, NEVER declare depends_on as a simple string list (depends_on: ['db']). Docker Compose starts containers in parallel; a container marked as 'started' does not mean PostgreSQL is ready to accept connections. Always define explicit healthcheck blocks and set condition: service_healthy.

## Strict Guidelines
- MUST define an explicit healthcheck on database and cache services (e.g. pg_isready -U postgres).
- MUST configure depends_on with condition: service_healthy on all consuming web and API services.
- MUST set appropriate interval (5s), timeout (3s), and retries (5) on healthcheck definitions.
- MUST NOT write arbitrary sleep loops inside application startup scripts as a substitute for healthchecks.
- SHOULD use modern top-level compose.yaml naming convention (Compose Specification v2).

## Bad vs Good Implementations
### Deterministic Service Startup with service_healthy Condition

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: PostgreSQL takes 3 to 10 seconds to initialize tables and accept socket connections. The API container starts immediately and crashes with connection refused.
```yaml
# FATAL: Naive depends_on starts api while postgres is still initializing
services:
  db:
    image: postgres:16
  api:
    image: my-api:latest
    # BROKEN: api starts immediately when db container is created, crashes on connection refused!
    depends_on:
      - db
```

#### Production Standard (Correct)
> **Standard**: Defines pg_isready healthcheck on PostgreSQL. Docker Compose holds back the API service until the healthcheck returns status 0, eliminating startup race conditions.
```yaml
services:
  db:
    image: postgres:16
    environment:
      POSTGRES_DB: app
      POSTGRES_USER: user
      POSTGRES_PASSWORD: secretpassword
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U user -d app"]
      interval: 3s
      timeout: 3s
      retries: 5
      start_period: 5s

  api:
    image: my-api:latest
    depends_on:
      db:
        condition: service_healthy # Starts ONLY when postgres is genuinely ready!
```

Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Docker Compose Spec Validator MCP

Validates Compose v2 files for missing service_healthy dependencies and healthchecks.

Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

askills: Docker Compose Healthcheck Builder

Adds deterministic healthchecks and service_healthy conditions to Compose files.

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Docker Compose v2 service_healthy Dependency Orchestration Standard

Docker Compose v2 service_healthy Dependency Orchestration Standard defines an industrial-grade behavioral standard for devops engineering. Production standard for multi-container orchestration in Docker Compose v2. Mandates using depends_on with condition: service_healthy instead of naive string list dependencies, preventing application containers from crashing upon startup while waiting for PostgreSQL or Redis readiness. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: AI writes depends_on: ['db'] without healthchecks, causing backend containers to crash immediately because the database container has started but cannot yet accept connections. Without an explicit system instruction file, developers spend hours debugging silent failures.

Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	AI writes depends_on: ['db'] without healthchecks, causing backend containers to crash immediately because the database container has started but cannot yet accept connections.	High	Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production. Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture Inconsistency	AI assistants produce mixed paradigms across files, creating fragmented codebase conventions.	Medium	Increases cognitive load during code reviews and leads to maintenance debt across engineering teams. Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.

Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

MUST define an explicit healthcheck on database and cache services (e.g. pg_isready -U postgres).

MUST define an explicit healthcheck on database and cache services (e.g. pg_isready -U postgres).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

2

MUST configure depends_on with condition

MUST configure depends_on with condition: service_healthy on all consuming web and API services.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

3

MUST set appropriate interval (5s), timeout (3s), and retries (5) on healthcheck definitions.

MUST set appropriate interval (5s), timeout (3s), and retries (5) on healthcheck definitions.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

4

MUST NOT write arbitrary sleep loops inside application startup scripts as a substitute for healthchecks.

MUST NOT write arbitrary sleep loops inside application startup scripts as a substitute for healthchecks.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

5

SHOULD use modern top-level compose.yaml naming convention (Compose Specification v2).

SHOULD use modern top-level compose.yaml naming convention (Compose Specification v2).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Docker Compose v2 service_healthy Dependency Orchestration Standard critical for AI coding assistants?

Production standard for multi-container orchestration in Docker Compose v2. Mandates using depends_on with condition: service_healthy instead of naive string list dependencies, preventing application containers from crashing upon startup while waiting for PostgreSQL or Redis readiness. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (AI writes depends_on: ['db'] without healthchecks, causing backend containers to crash immediately because the database container has started but cannot yet accept connections.) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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