To troubleshoot YEDIS API connection issues, you should perform a number of checks.

Are YugabyteDB processes running?

You should ensure that the expected YugabyteDB processes are on the current node. At a minimum, the YB-TServer process needs to be running to be able to connect to this node with a Redis client or application.

Additionally, depending on the setup, you might expect a master process to also be running on this node.

For detailed instructions, see Check processes.

Is the Redis-compatible YEDIS API running?

If the YB-TServer process is running, execute the following command to verify that the YEDIS API is enabled and listening on the Redis port (default 6379):

lsof -i :6379
COMMAND     PID   USER   FD   TYPE     DEVICE SIZE/OFF NODE NAME
yb-tserve 81590 centos   92u  IPv4 0xdeadbeef      0t0  TCP localhost:6379 (LISTEN)

You may need to install lsof first.

When running a local cluster with yb-ctl, you should see all the nodes with different IP addresses, as per the following example:

lsof -i :6379
COMMAND     PID   USER   FD   TYPE     DEVICE SIZE/OFF NODE NAME
yb-tserve 81590 centos   92u  IPv4 0xdeadbeef      0t0  TCP localhost:6379 (LISTEN)
yb-tserve 81593 centos   92u  IPv4 0xdeadbeef      0t0  TCP 127.0.0.2:6379 (LISTEN)
yb-tserve 81596 centos   92u  IPv4 0xdeadbeef      0t0  TCP 127.0.0.3:6379 (LISTEN)

If another process is using this port, you might need to stop that and restart the YB-TServer process. Otherwise, if no process is listening but the YB-TServer is running, check the value of the --cql_proxy_bind_address flag passed to the YB-TServer process.

Can redis-cli connect locally?

Use redis-cli to connect to the local node, as follows:

./redis-cli -h <yb-local-address>

Depending on your configuration, you may need to install redis-cli. For more information, see Initialize YEDIS API and connect with redis-cli.

In the preceding command, <yb-local-address> is the address where the YEDIS service is listening (for example, as returned by lsof).

If redis-cli can connect, the issue is likely a network issue with the original client not being able to access this node where YugabyteDB is running.

Otherwise, you might need to use the the yb-admin tool to run the following command:

.bin/yb-admin --master_addresses <master-ip-addresses> setup_redis_table