Patroni is an open-source template for creating highly available PostgreSQL clusters. It manages automatic failover, leader election, and streaming replication using a distributed configuration store (DCS).

This bounty will be paid out when:

• A high-quality Patroni Railway template is presented
• All potential template feedback has been incorporated
• All requirements are met and tested

Template Requirements

• Multi-service deployment including Multiple PostgreSQL/Patroni nodes (2-3 nodes), a distributed configuration store (etcd cluster recommended), and a connection pooler/load balancer (HAProxy or PgPool)
• Volume-backed storage for PostgreSQL data directories to preserve data across redeploys
• Volume-backed storage for the DCS (etcd) data directory to maintain cluster state
• Service dependencies should be correctly configured with proper startup order and health checks between the DCS, Patroni/PostgreSQL nodes, and load balancer
• Environment variables properly configured for Railway domains; internal services should use the private network (.railway.internal) to communicate
• Load balancer should be configured to route write traffic to the primary node and optionally load-balance read traffic across replicas
• Template should expose the load balancer endpoint for users to connect their applications to the PostgreSQL cluster

Some Additional Context

This one's a complex deployment, some challenges to think about:

1. Private Networking: Railway now supports IPv4 private networking which should help simplify etcd configuration (compared to IPv6-only networking)
2. etcd Cluster Bootstrap: etcd requires all members to successfully start for initial bootstrap. Consider using etcd's discovery service or DNS-based discovery rather than hardcoded IPs, since container addresses can change on redeploy
3. Startup Ordering: The DCS (etcd) must be healthy before Patroni nodes can initialize. Patroni nodes need proper retry/wait logic or health check dependencies.

Highly encourage contributors to use this thread to chat about any issues you might run into 🤝

A few resources to get you started:

• Learn more about Railway Templates
• Railway Private Networking Guide
• Patroni Documentation
• Patroni Docker Compose Example
• Patroni Docker README
• Patroni GitHub Repository
• etcd Clustering Guide
• Railway Documentation