!feat: Allow Multiple Core gRPC Connections with Load Balancing

[smuu]

Multiple Core gRPC Connections with Client-Side Load Balancing

Motivation

Celestia nodes currently support only a single core gRPC connection, creating a potential single point of failure. This PR enhances reliability and performance by supporting multiple core endpoints with client-side load balancing.

Key Benefits

• Improved Reliability: Node operations continue if some endpoints fail
• Load Distribution: Requests are balanced across multiple endpoints
• Enhanced Performance: Transaction submissions and block fetching distributed for better throughput
• Simple Configuration: No external load balancers needed

Implementation

• Added support for multiple endpoints in configuration
• Implemented round-robin load balancing for block fetching and transaction submission
• Added flexible endpoint configuration with TLS and authentication options
• Maintained backward compatibility with existing single-endpoint configuration
• Added IPv6 support

Usage

Single endpoint (backward compatible):

celestia bridge start --core.ip=127.0.0.1 --core.grpc.port=9090

Multiple endpoints:

celestia bridge start \
  --core.endpoints=127.0.0.1:9090 \
  --core.endpoints=127.0.0.2:9090 \
  --core.endpoints=example.com:9090:tls=true:xtoken=/path/to/token

This enhancement allows Celestia nodes to continue operating even if some core endpoints fail while balancing load for better performance and throughput.

[cristaloleg]

Ideally this should be a CAS loop

[Wondertan]

AI cooked in here :)

Is there a plan to add load balancing for transaction submission? While having it for block fetching is useful, its not the weakest link our users struggling with.

[smuu]

AI cooked in here :)

Is there a plan to add load balancing for transaction submission? While having it for block fetching is useful, its not the weakest link our users struggling with.

Added a proposal how the tx submission load balancing could look like.