Static Filter: support multiple positional parameters

[yaauie]

When multiple prepared_parameters are passed to the local lookup, the Sequel library raises an exception with Mismatched number of placeholders even when the provided query has the correct number of placeholders. Our unit specs stub out the prepared statement details and therefore do not show off the issue.

There is a workaround listed at the end of this Issue.

This PR introduces a failing spec showing the behaviour when

• the local lookup is configured with:
  • query => "SELECT * FROM servers WHERE ip = ? AND name = ?"
  • prepared_parameters => ["[host][ip]", "[host][name]"]
• using an event with the structure:
  • "host" : { "ip" : "10.3.1.1", "name" : "mv-server-1"}, "message" : "ping"}

Failures:

  1) LogStash::Filters::JdbcStatic non scheduled operation under normal conditions with prepared statement with multiple positional parameters enhances an event
     Failure/Error: @db[statement, parameters].prepare(:select, @id)

     Sequel::Error:
       Mismatched number of placeholders (2) and placeholder arguments (1) when using placeholder string
     # ./lib/logstash/filters/jdbc/read_write_database.rb:32:in `prepare'
     # ./lib/logstash/filters/jdbc/lookup.rb:117:in `prepare'
     # ./lib/logstash/filters/jdbc/lookup_processor.rb:68:in `block in create_prepared_statements_for_lookups'
     # ./lib/logstash/filters/jdbc/lookup_processor.rb:66:in `create_prepared_statements_for_lookups'
     # ./lib/logstash/filters/jdbc/lookup_processor.rb:42:in `initialize'
     # ./lib/logstash/filters/jdbc_static.rb:191:in `prepare_runner'
     # ./lib/logstash/filters/jdbc_static.rb:155:in `register'
     # ./spec/filters/integration/jdbc_static_spec.rb:153:in `block in Filters'

Finished in 9.43 seconds (files took 9.28 seconds to load)
18 examples, 1 failure

Failed examples:

rspec ./spec/filters/integration/jdbc_static_spec.rb:152 # LogStash::Filters::JdbcStatic non scheduled operation under normal conditions with prepared statement with multiple positional parameters enhances an event

Workaround

Instead of using prepared statements and positional_parameters, it is safe to use a regular query with named placeholders and the parameters option, as demonstrated by a companion integration spec in this PR:

• the local lookup is configured with:
  • query => "SELECT * FROM servers WHERE ip = :host_ip AND name = :host_name"
  • prepared_parameters => {"host_ip" => "[host][ip]" "host_name" => "[host][name]" }
• using an event with the same structure as before:
  • "host" : { "ip" : "10.3.1.1", "name" : "mv-server-1"}, "message" : "ping"}