Sentinel Mode instance role mismatch #1095
Description
Hello,
We are sometimes seeing this error while trying to configure the client to connect to the master node in a 3 node sentinel setup:
Redis::ConnectionError (Instance role mismatch. Expected master, got slave.)
For example:
module DataCache class << self def redis @redis ||= Redis.new(redis_opts) end def redis_opts svc = 'redis-headless' # query headless svc to get all sentinel addresses sentinels = Resolv.getaddresses(svc).map do |address| { host: address, port: 26379, password: ENV["REDIS_PASSWORD"] } end # connect to master for read/write { host: "mymaster", sentinels: sentinels, password: ENV["REDIS_PASSWORD"], role: :master } end end end irb(main):017:0> DataCache.redis => #<Redis client v4.6.0 for redis://redis-node-1.redis-headless.redis-namespace.svc.cluster.local:6379/0> irb(main):018:0> DataCache.redis_opts => {:host=>"mymaster", :sentinels=>[{:host=>"10.0.3.247", :port=>26379, :password=>"###"}, {:host=>"10.0.2.40", :port=>26379, :password=>"###"}, {:host=>"10.0.3.36", :port=>26379, :password=>"###"}], :password=>"###", :role=>:master} irb(main):019:0> DataCache.redis.get('testkey') Traceback (most recent call last): 2: from (irb):19 1: from (eval):5:in `call' Redis::ConnectionError (Instance role mismatch. Expected master, got slave.) irb(main):020:0> Our setup (mostly aligned with this one) includes 1 master and 2 slave nodes. It is unclear to me how the client ever gets connected to a slave node given we are configuring it with role :master? But it appears to be selecting any of the 3 nodes indiscriminately (there is no error on the times when the client correctly connects to the master node)
127.0.0.1:26379> sentinel master mymaster 1) "name" 2) "mymaster" 3) "ip" 4) "redis-node-2.redis-headless.redis-namespace.svc.cluster.local" I'm hoping I just have something misconfigured and someone might kindly point me in the right direction