redis.sentinel.SlaveNotFoundError: No slave found for 'mymaster'

[alelomonaco]

Name and Version
redis: 7.2.3
dogpile.cache: 1.2.2
redis-py: 5.0.1

What steps will reproduce the bug?

Deploy a Redis cluster with sentinel and auth enabled, create a script to call sentinel host and retrieve data from cache:

import dogpile.cache
import time
import logging
import redis

# Set the log level to DEBUG for Dogpilecache
logging.basicConfig(level=logging.DEBUG)

# Create a Dogpilecache region
cache_region = dogpile.cache.make_region().configure(
    'dogpile.cache.redis_sentinel',
    arguments={
        'sentinels': [
            ['redis-cluster', 26379],
        ],
        'sentinel_kwargs': {
            'password': 'mypassword',
        }
    }
)


def get_data_from_cache(key):
    # Try retrieving data from cache
    data = cache_region.get(key)

    if data is not None:
        print(f"Data found in cache: {data}")
    else:
        print("Data not found in cache")
        # Simulating a time-consuming operation to fetch the data
        time.sleep(2)
        data = f"Sample data for {key}"
        # Store the data in cache for future use
        cache_region.set(key, data)
        print(f"Data stored in cache: {data}")

    return data


# Perform data retrieval using Dogpilecache
print(redis.__version__)
result = get_data_from_cache("example_key")
print(f"Final result: {result}")

Are you using any custom parameters or values?
I'm sure about every parameter because without auth, script works as expected, the only parameter I cannot trust is password in sentinel_kwargs. I'm also sure that problem is on dogpile.cache because from the same client it works with redis-cli or with a python script like this:

import redis

# Create a Redis Sentinel connection
sentinel = redis.Redis(
    host='redis-cluster',
    port=26379,
    password='mypassword',
    decode_responses=True
)

# Get the replicas (slaves) of the master
replicas = sentinel.sentinel_slaves('mymaster')

# Iterate through replicas and print their IP and port
for replica in replicas:
    replica_host = replica['ip']
    replica_port = replica['port']
    print(f"Replica: {replica_host}:{replica_port}")

What is the expected behavior?
same output obtained when auth is disabled:
5.0.1
Data found in cache: <dogpile.cache.api.NoValue object>
Final result: <dogpile.cache.api.NoValue object>

What do you see instead?
redis.sentinel.SlaveNotFoundError: No slave found for 'mymaster

Additional information
Redis cluster is deployed through bitnami helm chart.
I've tried different version of dogpile.cache (1.1.8 and 1.1.0), same result.

I've tried to add decode_responses parameter, same result.
Network and name resolution are ok. It works without auth and with auth enable but without dogpile.cache (like redis-cli and redis-py).

[zzzeek]

hi -

unfortunately I know nothing about this driver or what might be causing your problem. can you perhaps inspect and/or debug the source code for dogpile's connector directly to see what parameters are not being passed in the way expected? in particular I notice you are using a parameter "decode_responses", that we dont seem to have. thanks

[alelomonaco]

problem is on the dogpile.cache script, decode_responses is defined on the redis-py script and anyway it works both with and without. I suspect passowrd is not set in the rigth way:
'sentinel_kwargs': {
'password': 'mypassword',
}
is there any documentation about how to set the password for sentinel?

[zzzeek]

not really, this was some feature that was kind of a drive-by contribution so what you see in the source is the best thing to look at. there's not much happening there, this is all just a pass-through.

[zzzeek]

docs are here: https://dogpilecache.sqlalchemy.org/en/latest/api.html#dogpile.cache.backends.redis.RedisSentinelBackend

[alelomonaco]

fixed adding also connection kwargs. sentinel password is used to connect to sentinel but to connect to the master node connection kwargs has to be set. If user is default, username field can be omitted.

cache_region = dogpile.cache.make_region().configure(
'dogpile.cache.redis_sentinel',
arguments={
'sentinels': [
['redis-cluster', 26379],
],
'sentinel_kwargs': {
'password': 'mypassword',
}
'connection_kwargs': {
'password': 'mypassword',
}
}
)