Unable to connect to redis that listening on IPv6 interface

[morawskim]

Hello,

The redis-commander has problem with connecting to redis that listening on IPv6 interface.

I deployed rediscommander using image rediscommander/redis-commander:latest (docker.io/rediscommander/redis-commander@sha256:19cd0c49f418779fa2822a0496c5e6516d0c792effc39ed20089e6268477e40a ). When I tried to connect to configured redis server (added by env variable) in logs I noticed errors:

MaxRetriesPerRequestError: Reached the max retries per request limit (which is 20). Refer to "maxRetriesPerRequest" option for details.                                           
    at Socket.<anonymous> (/redis-commander/node_modules/ioredis/built/redis/event_handler.js:176:37)                                                                   
    at Object.onceWrapper (events.js:421:26)
    at Socket.emit (events.js:314:20)
    at TCP.<anonymous> (net.js:675:12)
setUpConnection (R:redis:6379:0) Redis error Error: getaddrinfo ENOTFOUND redis                                                                                                                            
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:66:26)

I changed my deployment manifest. I added:

#...
      securityContext:
        runAsUser: 0

After this change I was able to exec to running pod with root privileges.
I installed redis.
Using redis-cli -h redis I was able to connect to redis instance and call ping command.

I checked source code and i found this -

redis-commander/lib/util.js

Line 322 in 942142f

family: 4

Object.assign(redisOpts, {
    port: clientConfig.port,
    host: clientConfig.host,
    path: clientConfig.path,
    family: 4
});

I changed the value of family property to 6.
I ran ps -ef to see running commands.
I decided to ran a new instane of redis-commander on a different port: /usr/bin/node ./bin/redis-commander --port 8082 --redis-port tcp://[fd2e:565e:ab48::XXXX]:6379.
I used kubectl port-forward to connect to a new redis-commander instance and everything worked - I connected to redis and I saw all my keys in db.

At the moment neither minikube (https://minikube.sigs.k8s.io/docs/faq/#does-minikube-support-ipv6) nor microk8s (canonical/microk8s#1343) support IPv6 stack. So I cannot prepare example.
I have access to k8s cluster which run on ipv6 stack, so I am able to test fix.

[sseide]

Hi, thanks for the report.

As a short recap from your tests/doings:

• in principal it is possible to connect to Redis with IPv6
• changing the family for ioredis connection properties is neccessary
• additionally docker runtime / kubernetes cluster must be reconfigured to use IPv6 (i know its not possible out-of-the-box)

After theses steps its working...

Base on this i can prepare a Change and push it this week. Please correct me if i'm wrong or missed something as i do not know if i can setup an test environment locally right now.

And another note - since some time its not possible to update the dockerhub image anymore. Latest versions are available from gcr.io - please check projects README here for up to date image repo.

Best regards,
S. Seide

[morawskim]

Yeap everything correct. I am waiting for patch to test it.

I will use image from gcr.io registry, thanks for info.

I also thought about create a test env in virtualbox, but there are some issues also with VB and IPv6 :/
I had to manually add a NAT network for VB on Linux (vagrant was not able to create IPv6 network/assign IPv6 address) - this thread can be useful https://askubuntu.com/questions/803102/virtualbox-no-ipv6-in-ubuntu-guest-win10-host (the steps are the same also for linux)

[sseide]

latest Version from gcr.io should work. Can you please test it? Runing locally it can connect to IPv6 server.

Using Docker you may set the env var REDIS_HOST=fd2e:565e:ab48::XXXX (no bracket). REDIS_PORT is not needed as long as it is the default 6379.

Booth REDIS_HOSTS and SENTINEL_HOSTS (plural) to set multiple connections at once do not work with IPv6 addresses currently. Do you know a simple way in Shell/Bash to split IPv6 addresses and ports?

And thanks for VB/Vagrant info - used it to update my redis test vm for ipv6 connectivity.

[morawskim]

Hello,

I have tested the latest version. Everything works. Thanks.

Do you know a simple way in Shell/Bash to split IPv6 addresses and ports?

This doesn't look like a trivial task. The ENTRYPOINT script accept entry in REDIS_HOSTS as label:hostname:port:dbIndex:password
I created test script. The only idea I have, is to wrap a IPv6 address into square brackets.

First we can check whether hostname looks like ipv4, then check first character (whether is equals to [) and then assume that this is hostname.
But still there can be issue with current template in REDIST_HOSTS, because contains information not only about hostname and port, but also about dbindex and password.

#!/bin/bash -e

IP_ADDRESSES=(
    '2001:0db8:85a3:0000:0000:8a2e:0370:7334:PORTHERE'
    '2001:0db8:85a3:0000:0000:8a2e:0370:7334'
    '127.0.0.1:PORTHERE'
    '127.0.0.1'
    '[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:PORTHERE'
    '[2001:0db8:85a3:0000:0000:8a2e:0370:7334]'
    'dnsname'
    'dnsname:PORTHERE'
)

for ip in ${IP_ADDRESSES[@]}; do
  printf ">>> %52s" $ip
  echo

  if [[ $ip =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+ ]]; then
    chunks=($(echo $ip | sed 's|\(.*\):|\1 |'))
  elif [[ $ip =~ ^\[ ]]; then
    chunks=($(echo $ip | sed 's|\(.*\)]:|\1] |'))
  else
    chunks=($(echo $ip | sed 's|\(.*\):|\1 |'))
  fi

  printf "IP: %52s   PORT: %4s" ${chunks[0]:-''} ${chunks[1]:-6379}
  echo
  echo
done

Which gives results

>>>     2001:0db8:85a3:0000:0000:8a2e:0370:7334:PORTHERE
IP:              2001:0db8:85a3:0000:0000:8a2e:0370:7334   PORT: PORTHERE

>>>              2001:0db8:85a3:0000:0000:8a2e:0370:7334
IP:                   2001:0db8:85a3:0000:0000:8a2e:0370   PORT: 7334

>>>                                   127.0.0.1:PORTHERE
IP:                                            127.0.0.1   PORT: PORTHERE

>>>                                            127.0.0.1
IP:                                            127.0.0.1   PORT: 6379

>>>   [2001:0db8:85a3:0000:0000:8a2e:0370:7334]:PORTHERE
IP:            [2001:0db8:85a3:0000:0000:8a2e:0370:7334]   PORT: PORTHERE

>>>            [2001:0db8:85a3:0000:0000:8a2e:0370:7334]
IP:            [2001:0db8:85a3:0000:0000:8a2e:0370:7334]   PORT: 6379

>>>                                              dnsname
IP:                                              dnsname   PORT: 6379

>>>                                     dnsname:PORTHERE
IP:                                              dnsname   PORT: PORTHERE

[sseide]

Many thanks for this. And having multiple fields like label and so on i say using square brackets for ipv6 addresses will be required for these envs vars. Makes parsing a lot easier than. Port and/or db number might be given and using the shortened ipv6 writing with "fd00::1" it is indistinguishable...

Writing "fd00::1:1024:1" means what?

• ipv6 "fd00::1:2048:1" with default port 6379 and default db 0 or
• ipv6 "fd00::1" with port 2048 and db 1
• and so on...

And maybe i parse these in nodejs, a little helper script called from the docker-startup like other regular programs might be easier than a pure shell script...