Changebase Ruby Library

The Changebase Ruby library provides convenient access to the Changebase API from applications written in the Ruby language.

gem install changebase

If you are installing via bundler:

gem "changebase"

In a controller you can use the following to log metadata with all updates during a request:

  class ApplicationController < ActionController::Base
    changebase do
      {
        request_id: request.uuid,
        user: {
          id: current_user.id
        }
      }
    end
  end

The changebase function can be called multiple times to include various data. To nest a value simply give it all the keys so it knows where to bury the value.

Below are several diffent way of including metadata:

  class ApplicationController < ActionController::Base

    # Just a block returning a hash of metadata.
    changebase do
        { my: data }
    end

    # Sets `release` in the metadata to the string RELEASE_SHA
    changebase :release, RELEASE_SHA

    # Sets `request_id` in the metadata to the value returned from the `Proc`
    changebase :request_id, -> { request.uuid }

    # Sets `user.id` in the metadata to the value returned from the
    # `current_user_id` function
    changebase :user, :id, :current_user_id

    # Sets `user.name` in the metadata to the value returned from the block
    changebase :user, :name do
      current_user.name
    end

    def current_user_id
      current_user.id
    end
  end

In the above example the following would be logged with all database changes:

{
  release:     'd5db29cd03a2ed055086cef9c31c252b4587d6d0',
  request_id:  'a39073a5-10b9-41b7-b5f0-06806853507b',
  user: {
    id:        'f06114cc-7819-4906-85dc-b93edb0fb08c',
    name:      'Tom'
  }
}

To include metadata when creating or modifying data with ActiveRecord:

  ActiveRecord::Base.with_metadata({user: {name: 'Tom'}}) do
    @post.update(title: "A new beging")
  end

The default mode for the changebase gem is replication. In this mode Changebase is setup to replicate your database and record events via the replication stream.

The default configuration in replication mode is to emit the metadata as messages, this requires no configuration. If this does not work you can configure metadata_mode to be "table". In table mode changebase will write metadata to the "changebase_metadata" table.

To configure the metadata table create an initializer at config/initializers/changebase.rb:

Rails.application.config.tap do |config|
  # Defaults:
  # config.changebase.metadata_mode = "message"
  # config.changebase.metadata_message_prefix = "changebase_metadata"
  config.changebase.metadata_mode = "table"
  config.changebase.metadata_table = "cool_custom_metadata_table"
end

If you are not using Rails you can configure Changebase directly via:

Changebase.metadata_mode = "table"
Changebase.metadata_table = "cool_custom_metadata_table"

Or

Changebase.configure(metadata_mode: "table", metadata_table: "cool_custom_metadata_table")

If you are unable to setup database replication you can use inline mode. Events will be sent to through the Changebase API. You will collect roughly the same information, but potentionally to miss events and changes in your database if you are not careful, or if another application accesses the database directly.

• Any changes made to the database by ActiveRecord that does not first instantiate the records will not be caputred. These methods include:
  • ActiveRecord::ConnectionAdapters::DatabaseStatements#execute
  • ActiveRecord::ConnectionAdapters::DatabaseStatements#exec_query
  • ActiveRecord::ConnectionAdapters::DatabaseStatements#exec_update
  • ActiveRecord::ConnectionAdapters::DatabaseStatements#exec_insert
  • ActiveRecord::ConnectionAdapters::DatabaseStatements#exec_delete
  • ActiveRecord::Persistence#delete
  • ActiveRecord::Persistence#update_column
  • ActiveRecord::Persistence#update_columns
  • ActiveRecord::Relation#touch_all
  • ActiveRecord::Relation#update_all
  • ActiveRecord::Relation#delete_all
  • ActiveRecord::Relation#delete_by
• Any changes made to the database outside of the Rails application will not be captured.
• Ordering of events will not be guaranteed. The timestamp will be used as the LSN, which may not be in the same order of transactions / events in the database.

To configure Changebase in the "inline" mode create a initializer at config/initializers/changebase.rb with the following:

Rails.application.config.tap do |config|
  config.changebase.mode = "inline"
  config.changebase.connection = "https://#{ ENV.fetch('CHANGEBASE_API_KEY') }@changebase.io"
end

If you are not using Rails you can configure Changebase directly via:

Changebase.configure do |changebase|
  changebase.mode = "inline"
  changebase.connection = "https://#{ ENV.fetch('CHANGEBASE_API_KEY') }@changebase.io"
end

# Or

Changebase.configure(
    mode: "inline",
    connection: "https://API_KEY@chanbase.io"
)

If you think you found a bug, please file a ticket on the issue tracker.