Class: Easymon::MultiActiveRecordCheck

Inherits:
Object
  • Object
show all
Defined in:
lib/easymon/checks/multi_active_record_check.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query: nil, &block) ⇒ MultiActiveRecordCheck

Here we pass a block so we get a fresh instance of ActiveRecord::Base or whatever other class we might be using to make database connections

For example, given the following other class: module Easymon

class PrimaryReplica < ActiveRecord::Base
  establish_connection :"primary_replica"
end

class OtherReplica < ActiveRecord::Base
  establish_connection :"other_replica"
end

end

We would check both it and ActiveRecord::Base like so: check = Easymon::MultiActiveRecordCheck.new {

{
  "Primary": ActiveRecord::Base.connection,
  "PrimaryReplica": Easymon::PrimaryReplica.connection
  "OtherReplica": Easymon::OtherReplica.connection
}

} Easymon::Repository.add(“multi-database”, check)

Optionally, a health check query can be given instead of relying on connection.active?. The query is run against each connection and must return a single truthy/falsey value (e.g. 1/0 from MySQL): check = Easymon::MultiActiveRecordCheck.new(query: “SELECT @@read_only”) {

{ "Primary": ActiveRecord::Base.connection }

}

A per-connection query can also be given by pairing the connection with its query. It takes precedence over the default query: option above: check = Easymon::MultiActiveRecordCheck.new {

{
  "Primary": [ActiveRecord::Base.connection, "SELECT @@read_only"],
  "PrimaryReplica": [Easymon::PrimaryReplica.connection, "SELECT TIMESTAMPDIFF(MICROSECOND, MAX(ts), NOW(6)) / 1000000 < 1 FROM percona.heartbeat"],
  "OtherReplica": Easymon::OtherReplica.connection # plain connection.active?
}

}



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# File 'lib/easymon/checks/multi_active_record_check.rb', line 48

def initialize(query: nil, &block)
  self.query = query
  self.block = block
end

Instance Attribute Details

#block ⇒ Object

Returns the value of attribute block.



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# File 'lib/easymon/checks/multi_active_record_check.rb', line 3

def block
  @block
end

#query ⇒ Object

Returns the value of attribute query.



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# File 'lib/easymon/checks/multi_active_record_check.rb', line 4

def query
  @query
end

#results ⇒ Object

Returns the value of attribute results.



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# File 'lib/easymon/checks/multi_active_record_check.rb', line 5

def results
  @results
end

Instance Method Details

#check ⇒ Object 



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# File 'lib/easymon/checks/multi_active_record_check.rb', line 53

def check
  connections = Hash(@block.call)

  results = connections.transform_values do |value|
    connection, connection_query = value.is_a?(Array) ? value : [ value, nil ]
    database_up?(connection, query: connection_query || query)
  end

  status = results.map { |db_name, result| "#{db_name}: #{result ? 'Up' : 'Down'}" }.join(" - ")

  [ (results.any? && results.values.all?), status ]
end