Redis::CannotConnectError: No sentinels available.

[palexvs]

Hello, I'm trying to setup sentinels, but i get error Redis::CannotConnectError: No sentinels available:

> redis = Redis.new(url: "redis://master.redis.com:6379/0", sentinels: [{host: "127.0.0.1", port: 26379}], master_name: :master)
> redis.zcount(1,0,'+inf')

Error:

Redis::CannotConnectError: No sentinels available.
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:551:in `sentinel_detect'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:555:in `resolve_master'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:519:in `resolve'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:317:in `establish_connection'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:94:in `block in connect'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:279:in `with_reconnect'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:93:in `connect'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:350:in `ensure_connected'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:207:in `block in process'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:292:in `logging'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:206:in `process'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis/client.rb:112:in `call'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic-redis-2.0.2/lib/newrelic_redis/instrumentation.rb:36:in `block in call_with_newrelic_trace'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic_rpm-3.12.0.288/lib/new_relic/agent/datastores.rb:111:in `block in wrap'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic_rpm-3.12.0.288/lib/new_relic/agent/method_tracer.rb:69:in `block in trace_execution_scoped'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic_rpm-3.12.0.288/lib/new_relic/agent/method_tracer_helpers.rb:82:in `trace_execution_scoped'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic_rpm-3.12.0.288/lib/new_relic/agent/method_tracer.rb:67:in `trace_execution_scoped'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic_rpm-3.12.0.288/lib/new_relic/agent/datastores.rb:108:in `wrap'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/newrelic-redis-2.0.2/lib/newrelic_redis/instrumentation.rb:35:in `call_with_newrelic_trace'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis.rb:1769:in `block in zcount'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis.rb:37:in `block in synchronize'
  from /opt/rbenv/versions/2.2.2/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis.rb:37:in `synchronize'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/redis-3.2.1/lib/redis.rb:1768:in `zcount'
  from (irb):66
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/railties-4.1.10/lib/rails/commands/console.rb:90:in `start'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/railties-4.1.10/lib/rails/commands/console.rb:9:in `start'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/railties-4.1.10/lib/rails/commands/commands_tasks.rb:69:in `console'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/railties-4.1.10/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
  from /home/rails/project/shared/bundle/ruby/2.2.0/gems/railties-4.1.10/lib/rails/commands.rb:17:in `<top (required)>'
  from ./bin/rails:8:in `require'
  from ./bin/rails:8:in `<main>'irb(main):067:0> 

But sentinel exists:

# redis-cli -p 26379
127.0.0.1:26379> info
# Server
redis_version:3.0.1
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:8114b371efa78b51
redis_mode:sentinel
os:Linux 3.13.0-24-generic x86_64
arch_bits:64
multiplexing_api:epoll
gcc_version:4.8.2
process_id:1130
run_id:2f09b36efcc4c99f94f5b9ed6d06ff52b61b78bb
tcp_port:26379
uptime_in_seconds:3884
uptime_in_days:0
hz:12
lru_clock:6879962
config_file:/etc/redis/redis.conf

# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
master0:name=master,status=ok,address=10.0.0.1:6379,slaves=1,sentinels=1

[palexvs]

Renamed master name identifies a group of Redis instances from master to master.redis.com and it works not
Is it possible to add setting master_name for that?

[nguyenductung]

I think the line 496 in lib/redis/client.rb should be

@master = @options[:master_name]

The current assignment causes client.call(["sentinel", "get-master-addr-by-name", @master]) to return nil because master name is wrong.

def resolve_master
  sentinel_detect do |client|
    if reply = client.call(["sentinel", "get-master-addr-by-name", @master])
      {:host => reply[0], :port => reply[1]}
   end
  end
end

https://github.com/redis/redis-rb/blob/master/lib/redis/client.rb#L556

[badboy]

@nguyenductung We should still use the hostname if master_name is not set.
@palexvs So according to that redis-cli output your monitored master is called master, not master.redis.com. redis-rb takes the host as the master name to query, why did you use master.redis.com in the first place?

[nguyenductung]

@badboy But if the master name is different from the host name, it'll result in Redis::CannotConnectError: No sentinels available.

What about

@master = @options[:master_name] || @options[:host]

?

[palexvs]

@badboy , yes it was my mistake.
I have used redis-sentinel gem before, where is possible to define a name identifies a group of Redis instances in configuration different from master hostname using param master_name. It is very useful.
Is it possible to add this functionality to redis-rb too?

Also I found that options hash should contain only symbol keys. I spent a lot of time to find this reason of my issue. I have loaded config from YML file and had a hash with string keys: "host" => '', .... 'port' => ...

[badboy]

@nguyenductung The good thing: With Sentinel the hostname from that "redis URL" is only used for the master name anyway, so why should it be different? But yes, I can still see having this as an option as useful. Care to submit a PR?

[nguyenductung]

@badboy I sent my PR but the tests failed due to Errno::EADDRINUSE: Address already in use. How should I fix that?

[badboy]

Restarted it, this is just a not-so-safe test setup right now…

[jperville]

Looking forward to seeing the associated PR merged.

[brodock]

why is this issue is closed? problem still not fixed

[colin-byrne-1]

shooting in the dark here... looking for a fix:

I have the generally the same setup and identical error output as @palexvs:

My initializer:

Sidekiq.configure_client do |config|
  config.redis = { 
    master_name: 'util-master',
    sentinels: redis_config['sentinels'].map { |sentinel|
      { :host => sentinel, :port => 26379 }
    },
  }
end

and I know the master_name is correct. Here is my output that shows that:

# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
master0:name=util-master,status=ok,address=10.1.2.20:6379,slaves=2,sentinels=5

It seems that no matter which combination of master_names and other configs, I get Redis::CannotConnectError: No sentinels with the same backtrace as above.