- Secure transport protocol
- Authentication
- Authorization
- Storage/database
- Cache and cache invalidation
- Monitoring
- Alerting
- Logging
- Request/execution tracing
- Secrets & credentials management
- Secret rotation
- Service discovery
- Documentation
- Continuous integration:
- build
- test
- compile
- package
- deploy
- Tests for external services/dependencies
- Production testing
- Backups/snapshots
Those are the basic ones from a engineering perspective.
There are also 3-rd party licensing, security and various compliance requirements.