Initial commit: docker-service-architecture skill

Comprehensive skill for Docker containerization patterns including:
- Multi-service project organization (services/<name>/)
- Environment-specific deployments (dev/test/prod)
- 3-stage testing pipeline (unit/service/integration)
- Branch-isolated test environments with dynamic ports
- CI/CD pipeline with semantic versioning
- Rich test runner with context-efficient output
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---
name: docker-service-architecture
description: Use when setting up a new project with multiple services that need Docker containerization, multi-environment deployments (dev/test/prod), CI/CD pipelines, or multi-stage testing (unit/service/integration). Also use when adding testing infrastructure to existing Docker projects.
---
# Docker Service Architecture
## Overview
Pattern for organizing multi-service projects with Docker containerization, environment-specific deployments, and a 3-stage testing pipeline. Key principles: **service isolation**, **ephemeral test environments**, **branch-isolated testing**, and **context-efficient test output**.
## When to Use
- Setting up a new multi-service project
- Adding Docker containerization to existing services
- Creating CI/CD pipelines for containerized services
- Implementing multi-stage testing (unit → service → integration)
- Need parallel test execution across git branches
## Directory Structure
```
project/
├── services/
│ ├── service-a/
│ │ ├── Dockerfile
│ │ ├── pyproject.toml (or package.json)
│ │ ├── service_a/ # Source code
│ │ ├── tests/
│ │ │ ├── unit/ # No containers needed
│ │ │ └── integration/ # Needs service containers
│ │ └── deploy/
│ │ └── test/
│ │ └── docker-compose.yml # Service-isolated tests
│ └── service-b/
│ └── ... (same structure)
├── deploy/
│ ├── dev/
│ │ ├── docker-compose.yml
│ │ └── .env.example
│ ├── test/
│ │ └── docker-compose.yml # Full-stack integration
│ └── prod/
│ ├── docker-compose.yml
│ └── .env.example
├── scripts/
│ ├── test-runner.py # Rich progress display
│ ├── test-service.sh # Service-level test runner
│ ├── run-integration-tests.sh
│ └── get-test-instance-id.sh
├── .gitea/workflows/ # Or .github/workflows/
│ └── release.yml
└── Makefile
```
## 3-Stage Testing Pattern
```
┌─────────────┐ ┌─────────────┐ ┌─────────────────┐
│ Unit Tests │ ──► │Service Tests│ ──► │Integration Tests│
│ (no Docker) │ │(per-service)│ │ (full stack) │
└─────────────┘ └─────────────┘ └─────────────────┘
Fast Medium Slow
Mocked deps Real DB, mocked All services
external APIs together
```
**Fail-fast**: Each stage only runs if previous stage passes.
### Stage 1: Unit Tests
- **Location**: `services/<name>/tests/unit/`
- **Dependencies**: All mocked
- **Containers**: None
- **Speed**: Seconds
### Stage 2: Service Tests
- **Location**: `services/<name>/tests/integration/`
- **Config**: `services/<name>/deploy/test/docker-compose.yml`
- **Dependencies**: Real database, mocked external APIs
- **Containers**: Service + its direct dependencies only
- **Speed**: 30-60 seconds per service
### Stage 3: Integration Tests
- **Location**: `tests/integration/` or `services/<name>/tests/integration/`
- **Config**: `deploy/test/docker-compose.yml`
- **Dependencies**: All services running
- **Containers**: Full stack
- **Speed**: 1-3 minutes
## Test Environment Isolation
### Branch Isolation
Use `TEST_INSTANCE_ID` derived from git branch for parallel testing:
```bash
# scripts/get-test-instance-id.sh
#!/bin/bash
BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "unknown")
# Sanitize: replace non-alphanumeric with dash, limit length
echo "$BRANCH" | sed 's/[^a-zA-Z0-9]/-/g' | cut -c1-20
```
### Docker Compose with Instance ID
```yaml
# deploy/test/docker-compose.yml
services:
database:
container_name: mydb-test-${TEST_INSTANCE_ID}
# Use tmpfs for ephemeral storage (fast, stateless)
tmpfs:
- /var/lib/postgresql/data
# Dynamic ports - no conflicts
ports:
- "5432" # Docker assigns random host port
networks:
- test-network
networks:
test-network:
name: myproject-test-${TEST_INSTANCE_ID}
```
### Dynamic Port Discovery
```bash
# After containers start, discover assigned ports
API_PORT=$(docker compose port api 8000 | cut -d: -f2)
DB_PORT=$(docker compose port database 5432 | cut -d: -f2)
export TEST_API_URL="http://localhost:${API_PORT}"
export TEST_DATABASE_URL="postgresql://test:test@localhost:${DB_PORT}/testdb"
```
## Docker Compose Patterns
### Development Environment
```yaml
# deploy/dev/docker-compose.yml
services:
api:
build:
context: ../..
dockerfile: services/api/Dockerfile
ports:
- "${API_PORT:-8000}:8000" # Configurable external port
volumes:
# Mount source for hot-reload
- ../../services/api/src:/app/src:ro
depends_on:
database:
condition: service_healthy
healthcheck:
test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
interval: 30s
timeout: 10s
retries: 3
start_period: 60s
volumes:
postgres-data:
name: myproject-dev-postgres # Named volumes persist
```
### Test Environment
```yaml
# deploy/test/docker-compose.yml
services:
database:
# Ephemeral storage for speed
tmpfs:
- /var/lib/postgresql/data
# PostgreSQL tuning for tests
command: >
postgres
-c synchronous_commit=off
-c fsync=off
-c full_page_writes=off
healthcheck:
interval: 5s # Faster checks for tests
retries: 10
start_period: 10s
```
### Production Environment
```yaml
# deploy/prod/docker-compose.yml
services:
api:
restart: unless-stopped
deploy:
resources:
limits:
memory: 4G
cpus: "4"
reservations:
memory: 1G
logging:
driver: "json-file"
options:
max-size: "100m"
max-file: "10"
```
## CI/CD Pipeline
### Release Workflow (Gitea/GitHub Actions)
```yaml
# .gitea/workflows/release.yml
name: Release
on:
push:
tags:
- 'v[0-9]+.[0-9]+.[0-9]+*'
jobs:
test:
runs-on: ubuntu-latest
services:
postgres:
image: postgres:15
env:
POSTGRES_PASSWORD: test
options: --health-cmd pg_isready
steps:
- uses: actions/checkout@v4
- name: Run tests
run: make test
build:
needs: test # Only build if tests pass
runs-on: ubuntu-latest
strategy:
matrix:
service: [api, worker, frontend] # Build all services
steps:
- uses: actions/checkout@v4
- name: Extract version
id: version
run: |
VERSION=${GITHUB_REF#refs/tags/v}
echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
# Detect pre-release (contains hyphen: v1.0.0-beta)
[[ "$VERSION" == *-* ]] && echo "PRERELEASE=true" >> $GITHUB_OUTPUT
- name: Build and push
run: |
IMAGE=registry.example.com/myproject-${{ matrix.service }}
docker build -t $IMAGE:${{ steps.version.outputs.VERSION }} \
-f services/${{ matrix.service }}/Dockerfile .
docker push $IMAGE:${{ steps.version.outputs.VERSION }}
# Only tag 'latest' for stable releases
if [ "${{ steps.version.outputs.PRERELEASE }}" != "true" ]; then
docker tag $IMAGE:${{ steps.version.outputs.VERSION }} $IMAGE:latest
docker push $IMAGE:latest
fi
```
## Rich Test Runner
Context-efficient test output with real-time progress:
```python
# scripts/test-runner.py (simplified structure)
from rich.console import Console
from rich.live import Live
from rich.table import Table
class TestRunner:
def run_all(self, unit=True, service=True, integration=True):
with Live(console=self.console) as live:
if unit:
self.run_stage("Unit Tests", self.unit_targets)
if not self.all_passed:
return False # Fail fast
if service:
self.run_stage("Service Tests", self.service_targets)
if not self.all_passed:
return False
if integration:
self.run_stage("Integration Tests", self.integration_targets)
self.render_summary()
return self.all_passed
```
### Output Parsing
```python
# Parse pytest progress: "tests/test_foo.py::test_bar PASSED [ 45%]"
PYTEST_PROGRESS = re.compile(r"\[\s*(\d+)%\]")
PYTEST_SUMMARY = re.compile(r"(\d+) passed(?:.*?(\d+) failed)?")
# Parse vitest: "✓ src/foo.test.tsx (11 tests) 297ms"
VITEST_PASS = re.compile(r"\s+(.+\.tsx?)\s+\((\d+)\s+test")
```
### Display Format
```
Unit Tests
● price-db ━━━━━━━━━━░░░░░░░░░░ 52% 497/955 12.3s
→ test_data_quality_validation
✓ orchestrator 74/74 3.2s
○ frontend pending
Service Tests
○ price-db pending
○ orchestrator pending
```
## Makefile Integration
```makefile
VERBOSE ?= 0
test:
@python scripts/test-runner.py $(if $(filter 1,$(VERBOSE)),-v)
test-verbose:
@python scripts/test-runner.py -v
test-unit:
@$(MAKE) -C services/api test-unit VERBOSE=$(VERBOSE)
@$(MAKE) -C services/worker test-unit VERBOSE=$(VERBOSE)
test-service SERVICE:
@./scripts/test-service.sh $(SERVICE)
test-integration:
@./scripts/run-integration-tests.sh
test-infra-up:
@cd deploy/test && docker compose up -d --build --wait
test-infra-down:
@cd deploy/test && docker compose down -v
```
## Common Mistakes
| Mistake | Problem | Solution |
|---------|---------|----------|
| Fixed ports in test compose | Parallel runs conflict | Use dynamic ports: `ports: ["5432"]` |
| Persistent test volumes | Slow, stateful tests | Use `tmpfs` for ephemeral storage |
| No healthchecks | Race conditions on startup | Add healthcheck + `depends_on: condition: service_healthy` |
| Verbose test output | Context exhaustion | Use rich progress display, details only on failure |
| Single test stage | Slow feedback, hard to debug | Separate unit → service → integration |
| No branch isolation | Concurrent branches conflict | Use `TEST_INSTANCE_ID` from git branch |
| Building all services on every change | Slow CI | Use matrix strategy, only build changed services |
## Quick Reference
| Component | Dev | Test | Prod |
|-----------|-----|------|------|
| Storage | Named volumes | tmpfs | External mounts |
| Ports | Fixed (configurable) | Dynamic | Fixed |
| Healthcheck interval | 30s | 5s | 30s |
| Restart policy | None | None | unless-stopped |
| Resource limits | None | None | Set limits |
| Logging | Default | Default | json-file with rotation |
## Service Test Script Template
```bash
#!/bin/bash
# scripts/test-service.sh
set -e
SERVICE=$1
TEST_INSTANCE_ID=$(./scripts/get-test-instance-id.sh)
export TEST_INSTANCE_ID
# Start service-specific containers
cd "services/${SERVICE}/deploy/test"
docker compose up -d --build --wait
# Discover ports
API_PORT=$(docker compose port api 8000 | cut -d: -f2)
export TEST_API_URL="http://localhost:${API_PORT}"
# Run tests
cd "../.."
uv run pytest tests/integration/ --integration
TEST_EXIT=$?
# Cleanup
cd "deploy/test"
docker compose down -v
exit $TEST_EXIT
```