How to convert a YAML sequence to array

Question

I need to loop through a YAML sequence and build an array with the sequence items.

I assume my YAML sequence should look like this in my config/redis:

redis:
  host:
  port:
  sentinels:
    - 1.34.79.100
    - 1.45.79.101
    - 1.46.79.102

In my config/initializers/sidekiq.rb I have a configure_client block that looks like:

Sidekiq.configure_client do |config|
  config.redis = { 
    master_name: 'util-master'
    sentinels: [
      "sentinel://#{first_redis_sentinel}:23679"
      "sentinel://#{second_redis_sentinel}:23679"
      "sentinel://#{third_redis_sentinel}:23679"
    ],
    failover_reconnect_timeout: 20,
    url: "redis://#{redis_host}:6379/12" }
end

I don't know how to dynamically load the listed Redis sentinels into that array. Do I need to build that array outside of the hash and configure_client block?

Have you looked at the YAML and Psych documentation? YAML uses Psych to load and parse the data. You're looking for how to use load_file. — the Tin Man
– the Tin Man, Commented Nov 23, 2016 at 18:43

spickermann · Accepted Answer · 2016-11-24 07:18:58Z

2

I would do something like this:

require 'yaml'
redis_configuration = YAML.load_file(Rails.root.join('config', 'redis.yml'))

Sidekiq.configure_client do |config|
  config.redis = { 
    master_name: 'util-master'
    sentinels: redis_configuration['redis']['sentinels'].map { |sentinel|
      "sentinel://#{sentinel}:23679"
    },
    failover_reconnect_timeout: 20,
    url: "redis://#{redis_configuration['redis']['host']}:6379/12" 
  }
end

edited Nov 24, 2016 at 7:18

answered Nov 23, 2016 at 18:45

spickermann

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2 Comments

the Tin Man Over a year ago

You probably want load_file, not load. load expects a string containing the YAML to parse, whereas load_file wants a filename which it then reads and parses. Also, using config as the outer variable and also as the block's parameter isn't good practice.

spickermann Over a year ago

@theTinMan You are right, thanks. I fixed my answer.

frank184 · Accepted Answer · 2016-11-23 18:44:23Z

0

A YAML string can be converted back into Ruby data like so:

1.9.3-p551 :005 > yaml = <<YAML
1.9.3-p551 :006"> redis:
1.9.3-p551 :007">   host:
1.9.3-p551 :008">   port:
1.9.3-p551 :009">   sentinels:
1.9.3-p551 :010">     - 1.34.79.100 
1.9.3-p551 :011">     - 1.45.79.101
1.9.3-p551 :012">     - 1.46.79.102
1.9.3-p551 :013"> YAML
=> "redis:\n  host:\n  port:\n  sentinels:\n    - 1.34.79.100\n    - 1.45.79.101\n    - 1.46.79.102\n"
1.9.3-p551 :014 > YAML.load(yaml)
=> {"redis"=>{"host"=>nil, "port"=>nil, "sentinels"=>["1.34.79.100", "1.45.79.101", "1.46.79.102"]}}

answered Nov 23, 2016 at 18:44

frank184

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