Copilot instructions

1---
2description: Rails Deployment with Kamal
3applyTo: "config/deploy.yml"
4---
5 
6# Rails Deployment with Kamal
7 
8## Core Philosophy
9 
10- Deploy containerized Rails applications without complexity
11- Use Kamal for zero-downtime deployments
12- Keep deployment configuration simple and version controlled
13- Leverage Docker without becoming a Docker expert
14- Deploy anywhere with SSH access
15 
16## Kamal Principles
17 
18- One command deployments with automatic rollback
19- Built-in health checks and rolling updates
20- Integrated secret management
21- No Kubernetes complexity needed
22- Direct SSH-based deployment to servers
23 
24## Configuration Strategy
25 
26- Keep all deployment config in `config/deploy.yml`
27- Use environment-specific settings wisely
28- Store secrets securely with Kamal's encryption
29- Version control deployment configuration
30- Document server requirements clearly
31 
32## Server Prerequisites
33 
34- Ensure servers have Docker installed
35- Configure SSH access for deployment user
36- Set up firewall rules appropriately
37- Prepare SSL certificates if needed
38- Verify sufficient disk space and memory
39 
40## Environment Management
41 
42- Use Kamal's built-in environment variable handling
43- Separate secrets from non-sensitive configuration
44- Use `.env` files for local development only
45- Leverage Rails credentials for application secrets
46- Keep production passwords out of version control
47 
48## Container Strategy
49 
50- Build minimal production Docker images
51- Use multi-stage builds to reduce size
52- Install only production dependencies
53- Configure proper health check endpoints
54- Set appropriate resource limits
55 
56## Database Configuration
57 
58- Use managed databases when possible
59- Configure connection pooling appropriately
60- Set up automated backups
61- Use read replicas for scaling
62- Handle database migrations carefully
63 
64## Asset Management
65 
66- Precompile assets during Docker build
67- Use CDN for asset delivery
68- Configure proper cache headers
69- Compress assets appropriately
70- Handle asset versioning correctly
71 
72## Health Checks
73 
74- Implement `/up` endpoint for health monitoring
75- Check database connectivity
76- Verify background job processing
77- Monitor external service dependencies
78- Return appropriate status codes
79 
80## Deployment Workflow
81 
82- Run tests before deployment
83- Build Docker image with correct tags
84- Push to container registry
85- Deploy with health check verification
86- Monitor deployment progress
87 
88## Zero-Downtime Deployments
89 
90- Use Kamal's rolling deployment strategy
91- Ensure backwards-compatible migrations
92- Handle long-running requests gracefully
93- Implement proper connection draining
94- Test rollback procedures
95 
96## SSL and Security
97 
98- Use Let's Encrypt for SSL certificates
99- Configure Traefik for SSL termination
100- Implement proper security headers
101- Keep containers updated
102- Monitor for security vulnerabilities
103 
104## Logging and Monitoring
105 
106- Centralize application logs
107- Use structured logging format
108- Monitor application performance
109- Set up error tracking
110- Configure alerting rules
111 
112## Background Jobs
113 
114- Deploy workers alongside web servers
115- Configure appropriate concurrency
116- Monitor job queue depth
117- Handle worker restarts gracefully
118- Separate critical from bulk job workers
119 
120## Scaling Strategy
121 
122- Start with vertical scaling
123- Add horizontal scaling when needed
124- Use load balancer health checks
125- Monitor resource utilization
126- Plan capacity ahead of demand
127 
128## Backup and Recovery
129 
130- Automate database backups
131- Test restore procedures regularly
132- Back up uploaded files
133- Document recovery procedures
134- Store backups in multiple locations
135 
136## Performance Optimization
137 
138- Use HTTP/2 where possible
139- Enable gzip compression
140- Configure appropriate timeouts
141- Monitor response times
142- Optimize container startup time
143 
144## Troubleshooting
145 
146- Use Kamal's built-in debugging commands
147- Access container logs easily
148- Connect to running containers
149- Monitor deployment events
150- Keep rollback procedures ready
151 
152## Maintenance
153 
154- Schedule maintenance windows
155- Communicate with users appropriately
156- Test updates in staging first
157- Monitor after deployments
158- Document common issues
159 
160## Cost Optimization
161 
162- Right-size server resources
163- Use spot instances where appropriate
164- Monitor resource utilization
165- Clean up unused resources
166- Optimize container image sizes
167 
168## Disaster Recovery
169 
170- Document recovery procedures
171- Test disaster scenarios
172- Maintain off-site backups
173- Have communication plan ready
174- Know your RTO and RPO
175 
176## Best Practices
177 
178- Deploy frequently in small batches
179- Automate everything possible
180- Monitor before, during, and after deploys
181- Keep deployment simple and boring
182- Document non-obvious decisions
183 
184## Common Patterns
185 
186- Blue-green deployments for critical updates
187- Canary deployments for gradual rollouts
188- Feature flags for controlled releases
189- Database migrations as separate step
190- Scheduled deployments for low-traffic periods
191 
192## Security Considerations
193 
194- Rotate credentials regularly
195- Use IAM roles where possible
196- Audit server access
197- Keep containers minimal
198- Scan images for vulnerabilities
199 
200Remember: Kamal makes deployment as simple as `kamal deploy`. Focus on your application, not deployment complexity.
201