redis-trib support to resolve hostname to IP address

[MasahikoSawada]

Currently, redis-trib can't resolve hostname to IP address, e.g., when it starts to create redis cluster.
Related to issue #2186.

[badboy]

This is a reasonable addition. If we want redis-trib to be the reference implementation of a Cluster management tool, we should make it easy to use, and that means allowing hostnames. Though we should properly document and communicate that Cluster itself deals only with IPs.

[andrepintorj]

This addition is a must have to facilitate the cluster's management.

[spuder]

+1

[jamesongithub]

boo, hit no password support, now no hostname support. is it faster to just issue redis command directly?

[dannyman]

2c: I get why we wouldn't want to do this: if the cluster internally sets up as IP addresses then do not give the illusion of supporting hostnames.

In practice, though, that changes my crib notes from something clean like:

./redis-trib.rb create --replicas 1 \
  host0 host1 host2 host3 host4 host5

To this sort of atrocity:

./redis-trib.rb create --replicas 1 \
  `host host0 | cut -d ' ' -f 4`:6379 \
  `host host1 | cut -d ' ' -f 4`:6379 \
  `host host2 | cut -d ' ' -f 4`:6379 \
  `host host3 | cut -d ' ' -f 4`:6379 \
  `host host4 | cut -d ' ' -f 4`:6379 \
  `host host5 | cut -d ' ' -f 4`:6379

Might I suggest:

• A flag that means "I understand you do IP addresses in the cluster config but please accept these hostnames for I am but a human"
• If someone feeds hostnames in but doesn't supply the flag, detect this situation and error out with like "You need to feed me IP addresses instead of hostnames!!"
• Do not require me to fill in the default port number.

Thanks,
-danny

[arunpmathew]

+1

[manolama]

2c: I get why we wouldn't want to do this: if the cluster internally sets up as IP addresses then do not give the illusion of supporting hostnames.

Wait, does Redis only support IPs internally for all operations or just clustering? The reason I ask is that I'm looking at setting up a fairly substantive cluster that would span multiple nodes. If a node dies, I can re-create it with the same hostname but the IP may change (due to the way our system handles virtual machines). If we're able to bring up a new VM with the same host, I'd love to see Redis auto-recover without having to remove the old IPs and add in the new ones and set new slaves.

+1 for internal hostname support!

[wolph]

Even without internal hostname support it would be so much more convenient to call the command with a hostname. Especially if you use some (zsh) shell-globbing:

redis-trib.rb create --replicas 1 redis-{00..07}:{7000..7015}

Instead of... well, you can guess how it'll be when I replace those with IP addresses ;)

[qvissak]

+1 for internal hostname support

[qvissak]

redis-server works with hostname/ip mapping. i.e sample docker-compose:

  redis_master:
   image: redis

  redis_slave:
    command: redis-server --slaveof redis_master 6379 <-- this is where the magic happens
    image: redis

[tculp]

@qvissak redis-server may support hostnames, but redis-cli -p 6379 cluster meet redismaster 6379 complains with "(error) ERR Invalid node address specified: redismaster:6379"

[AkashKrDutta]

As a workaround, why not use replicaof and provide the master hostname to slave (see here) like:

replicaof redis-master-0.redis-master.svc.cluster.local 6379

Edit: Ah, I am sorry. In cluster-mode you cannot set replica's with either config value of replicaof or from the COMMAND REPLICAOF. ERROR:

(error) ERR REPLICAOF not allowed in cluster mode.

[tculp]

Any update on this?

[artix75]

Any update on this?

@tculp redis-trib is no longer supported. New versions of redis use redis-cli --cluster instead.

[jordigarcl]

I get why this was closed, but no related ticket?

[nlalexandrov]

This is an issue for us too.
I have a wildcard TLS certificate. If I assemble my cluster with IP addresses, I get errors like these :
"Connection with Node 11c8443642680aebae33c5c74b7a5cf84617fb3c at :17001 failed: error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed"
If I generate a self signed certificate the same configuration works. So I guess I have to assemble the cluster with names in order to match my *domain certificate, but I can't...

[oranagra]

@jordigarcl @nlalexandrov all the code from redis-trib was moved to redis-cli, so this PR is no longer relevant. but it seems that redis-cli suffers from the same problem.
Anyone volunteers to make a PR to fix it? (or alternatively open a new issue with details and justifications)