Suggestion: Fail-fast on REST API port conflict to prevent silent misconfigurations

Klever Blockchain Feature Requests
1

Currently, when multiple nodes run on the same machine with identical REST API ports, only one can bind successfully. The others start but run without accessible REST APIs, causing:

  1. Heartbeat confusion: Both nodes report with different UniqueIDs, causing alternating producer records

  2. Silent failures: Nodes run unmonitorably without REST API access

  3. Wasted resources: Multiple nodes running unnecessarily in parallel

Discovery:

Through monitoring analysis, I’ve observed numerous misconfigurations where operators accidentally run multiple node instances (master + fallback, or even more) on the same port, leading to unpredictable behavior.

Proposed solution:

Add explicit port binding check at startup. If the port is already in use, the node should fail immediately with a clear error message. This forces operators to configure distinct ports (e.g., 8080, 8081) and prevents silent misconfigurations.

Example:

func main() {
    port := config.RestAPIPort
    
    // Attempt to bind the REST API port
    listener, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
    if err != nil {
        log.Fatalf("FATAL: Port %d is already in use. Cannot start node to prevent conflicts with other instances on the same machine.", port)
        os.Exit(1)
    }
    
    log.Printf("REST API successfully started on port %d", port)
    startNode(listener)
}
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