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I'm facing a MasterNotFoundError when I try to connect to the master node by following the deployment guide here: https://docs.bitnami.com/tutorials/deploy-redis-sentinel-production-cluster/

My code to connect to the master Redis Sentinel node is:

from redis.sentinel import Sentinel

redis_host = 'redis.default.svc.cluster.local'
redis_port = 26379
sentinel = Sentinel([(redis_host, redis_port)], socket_timeout=0.1, password='abc')
redis_client = sentinel.master_for('mymaster', password='abc')

In their GitHub repo, I see that the config for sentinel.masterSet is set to mymaster by default. But when I try to increment using the code below:

redis_client.incr('counter', 1)

I face the redis.sentinel.MasterNotFoundError: No master found for 'mymaster' error.

How can I solve this? Thanks.

phatasma-coder
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2 Answers2

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As reported here https://github.com/andymccurdy/redis-py/issues/1125 setting a low socket_timeout can cause a MasterNotFound error as each instance is polled but doesn't respond in time. You could increase the timeout or remove it to see if that fixes it.

SebG
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Where are you executing that code? If you are trying to connect from outside the cluster you will need to set the service as LoadBalancerIP. Have you tested if you have direct connection to that host before executing the code? using, for example, ping. Here you can see how to deploy the sentinel service as LoadBalancer: https://github.com/bitnami/charts/tree/master/bitnami/redis. You will need to set sentinel.service.type to LoadBalancerIP. I hope this will help you.

miguelaeh
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  • I'm executing the code from a pod inside the cluster – phatasma-coder Apr 04 '20 at 04:43
  • @phatasma-coder are you using the "values-production.yaml" to deploy the chart. If that's the case, please note that it enables a "networkPolicy" that restricts the access to the Redis pods. See https://github.com/bitnami/charts/blob/master/bitnami/redis/values-production.yaml#L141 As it's explained in the NOTES.txt (https://github.com/bitnami/charts/blob/master/bitnami/redis/templates/NOTES.txt#L57) your POD must have a special label so the network policy allows it to access Redis. – Juan Ariza May 12 '20 at 07:10