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Connectors Developer's Guide

So you want to customize Elastic-built connectors, or build your own? Well, you've come to the right place!

After you've made your changes, if you'd like to contribute back, please see the contributing guide.

Requirements

Setup

  1. Fork this repository

Installing dependencies

From the root level of this repository:

make install

Code Organization

  • config/connectors.yml: This is where the config lives. See Configuration for detailed explanation.
  • lib/app: This is where the connector service application and its helpers live.
  • lib/connectors: This is where the connector clients live. Each directory represent one connector client, e.g. mongodb, gitlab. The directory name must be the same as the service type. Connectors are hierarchical, so you may find that much of the underlying code for any given connector lives in lib/connectors/base/**/*.rb, rather than in the specific connector's implementation.
  • lib/core: The main components of the connector service application, e.g. scheduler, sync_job_runner, output_sync, etc..
  • lib/stubs: This is a holdover from migrating from Enterprise Search's monolithic codebase, and these files should eventually be refactored away.
  • lib/utility: This is where shared utilities, constants, error classes, etc.. live.
  • spec: This is where the tests live. All tests should match the path of the file/class that they test. For example a lib/foo/bar.rb should have a corresponding spec/foo/bar_spec.rb test file.

Add a custom connector

To add a new custom connector, all you have to do is adding a new directory under lib/connectors, and make it implement the connector protocol.

  1. Copy the example connector into a separate folder under the connectors (Ignore the [example_attachments] ). Rename the directory to the service type, and rename the class accordingly

    mkdir lib/connectors/{service_type}
cp lib/connectors/example/connector.rb lib/connectors/{service_type}/connector.rb

  2. Change self.service_type and self.display_name to match the connector you are implementing.

    def self.service_type
  'foobar'
end

def self.display_name
  'Foobar'
end

  3. Change self.configurable_fields to provide a list of fields you want to configure via the Kibana UI when connecting the connector. This method should return a hash, with the format of

    def self.configurable_fields
  {
    :key => { # The key to uniquely identify the configuration field
      :label => 'label', # The label to be displayed for the field in Kibana
      :value => 'default value', # The default value, optional
    }
  }
end

  4. Implement the do_health_check method to evaluate the connection to the third-party data source, depending on whether the method throws an exception or runs normally. E.g.

    def do_health_check
  foobar_client.health
end

  5. Customize initialize method if necessary. Make sure super is called to assign instance variable configuration, which contains all the info required to connect to the third-party data source.

  6. Implement the yield_documents method to sync data from the third-party data source. This is where your main logic goes to. This method should try to connect to the third-party data source, fetch data and transform to documents and yield them one by one. Each document is a hash and it must contain a key id, and it's unique across all the documents in one connector. Below is an example implementation:

    def yield_documents
  foobar_client.files do |file|
    yield {
      :id => file.id,
      :name => file.name,
      :size => file.size
    }
  end
end

    It's also possible to add a fail-safe mechanism to the method to also tolerate some of the errors that happen when yielding the documents. To do so you can use yield_with_handling_tolerable_errors function:

    def yield_documents
  foobar_client.files do |file|
    yield_with_handling_tolerable_errors do
      serialized_document = serialize(file)
      yield serialized_document
    end
  end
end

    The yield_with_handling_tolerable_errors function call will allow to tolerate some errors inside the block function passed to it and will raise only if too many consecutive errors happened (10 consecutive errors by default) or certain rate of errors was reached when yielding documents (15% documents out of 100 last documents).

  7. Register your new connector in Connectors::REGISTRY. E.g.

    require_relative 'foobar/connector'
REGISTRY.register(Connectors::Foobar::Connector.service_type, Connectors::Foobar::Connector)

Test your connector

Once you have implemented your new connector, it's time to see how it integrates with Kibana (Refer to Elastic connectors on how to operate connectors in Kibana).

  1. Make sure you have Elasticsearch, Kibana and Enterprise Search running. By far the easiest way is to start an Elastic Cloud deployment at https://cloud.elastic.co

  2. Go to Kibana, Enterprise Search > Create an Elasticsearch index. Use the Build a connector option for an ingestion method to create an index.

  3. Create an API key to work with the connector. It should be done either using the Generate API key button under Configuration tab, which is available on the next step of the wizard, or by creating a new API key via Stack Management > Security > API keys > Create API key. The second way is more generic and will allow the same API key to be used for multiple connectors.

  4. Configure your connector service application (See Configuration). You need to configure the followings fields, and leave the rest as default.

    1. elasticsearch.cloud_id: Configure this if the Elasticsearch server is on Cloud. You can find the cloud_id on the deployment Overview page.
    2. elasticsearch.hosts: Configure this if the Elasticsearch server is deployed on-prem.
    3. elasticsearch.api_key: Configure the API key generated in step 3.
    4. native_mode: Set it to false.
    5. connector_id: You can find the connector_id in step 3 Deploy a connector under Configuration tab in Kibana.
    6. service_type: Configure it to the service type of your new connector.

  5. Run the connector service application with

    make run

  6. Now you should see the message Your connector {name} has connected to Enterprise Search successfully. under the Configuration tab.

  7. The configurable fields should also be displayed. Configure them accordingly.

  8. Go to the Overview page, the Ingestion sync should be Connected. Click the Sync button on the top-right corner to start a sync, and see if documents are successfully ingested.

Building

The repository can generate ruby gems (connectors service itself or shared connectors service library), if needed.

Generate Connector Service gem:

make build_service_gem

Generate shared Connector Services libraries gem:

make build_utility_gem

Testing

# ensure code standards
make lint

# run unit tests
make test

IDE and Debugging

This project is fairly simple and conventional as a bundler-based Ruby project, so any popular IDE with ruby support should work fine. The maintaining team uses several IDEs including Intellij, RubyMine, Sublime, and VSCode.

Debugging varies from IDE to IDE, but the gems ruby-debug-ide, pry-remote, pry-nav, and debase are all included in the Gemfile, and should be sufficient to power your debugging.

Backporting

We use a tool called backport

Setup

Configure backport to give it a GitHub access token.

Go to https://github.com/settings/tokens/new and generate a new personal access token. It requires the "repo" scope - Full control of private repositories. Copy the token string. Click "Enable SSO" and authorize this token for Swiftype and Elastic. Edit ~/.backport/config.json with the contents:

{
  "accessToken": "<access_token>",
  "username": "<github_username>"
}

Execution

Simply run:

yarn run backport --pr <your-pull-request-number>

Use the SPACE character to select the destination branch, the arrow keys to navigate, and ENTER to confirm your selection. Your backport PR will be generated for you.