Valkey Replication Sync Failure

Products

• VMware Tanzu for Valkey

Issue/Introduction

Valkey nodes fail to synchronize with the following error in replica logs:

* PRIMARY <-> REPLICA sync started
* Connecting to PRIMARY ###.##.###.#:0 # Error condition on socket for SYNC: Connection refused

Environment

• VMware Tanzu Valkey 9.0.0+

Cause

While it is possible to use non-TLS, TLS, or a mix of the two in Valkey, this issue can occur when ports are not configured correctly in the valkey.conf file:

port 0

The above configuration disables the non-TLS port but lacked the configuration for an active TLS port, so Valkey cannot establish synchronization resulting in an immediate connection refusal.

Resolution

Ensure ports are explicitly set to a valid listener port:

1. Verify the Valkey service instance configuration is accurate.
2. Decide if you want non-TLS, TLS, or both:
   1. non-TLS:

      port 6379
      tls-port 0

   2. TLS:

      port 0
      tls-port 6379

      1. If using TLS, ensure replication is also encrypted:

         tls-replication yes

   3. non-TLS and TLS:

      port 6379
      tls-port 6380

3. Restart nodes to make the configuration change take effect.
4. Verify the fix by checking info replication for master_link_status:up.