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Staging Provider

Installation

composer require keboola/staging-provider

Usage

The staging provider package helps you to properly configure input/output staging factory for various environments.

Typical use-case can be set up a Reader instance to access some data:

We start by creating a StrategyFactory needed by the reader. The strategy itself has no knowledge of which storage should be used with each staging type. This is what provider initializer does - configure the StrategyFactory for a specific type of staging.

To create a provider initializer we pass it:

• the StrategyFactory to initialize
• a workspace provider factory - used to access workspace information for workspace staging
  • ExistingWorkspaceProviderFactory in case we want to re-use existing workspace
  • ComponentWorkspaceProviderFactory in case we want a new workspace to be created (based on a component configuration)
• a data directory path used for local staging

Then we call initializeProviders method to configure the StrategyFactory for specific staging type. It's up to the caller to know, which staging type to configure:

• when working with components, each component has staging type defined in its configuration
• sandbox has the type deduced from its workspace
• etc.

The example above presents usage of InputProviderInitializer for configuration of input mapping StrategyFactory for a Reader. Similarly, we can use OutputProviderInitializer to configure output mapping StrategyFactory for a Writer.

Internals

The main objective of the library is to configure StrategyFactory so it knows which staging provider to use with each kind of storage.

Staging

Generally there are two kind of staging:

• local staging - used to store data locally on filesystem, represented by LocalStaging class
• workspace staging - used to store data in a workspace, represented by WorkspaceStagingInterface

Provider (staging provider)

The StrategyFactory does not use a staging directly but rather through a provider (ProviderInterface) so there is a provider implementation for each kind:

• LocalStagingProvider
• WorkspaceStagingProvider

The main reason the StrategyFactory does not use the staging directly is to achieve lazy initialization of the staging - provider instance is created during bootstrap, but the staging instance is only created when really used.

Workspace provider factory

Local staging is pretty simple, it contains just the path to data directory, provided by the caller. On the other hand things gets a bit more complicated with workspace staging as the provider may represent an already existing workspace or a configuration for creating a new workspace. To achieve this, caller must provide a WorkspaceProviderFactoryInterface. Currently there are 2 implementations:

• ExistingWorkspaceProviderFactory which creates a provider working with an existing workspace
• ComponentWorkspaceProviderFactory which creates a provider that creates a new workspace based on a component configuration

Development

First start with creating .env file from .env.dist.

To run tests, there is a separate service for each PHP major version (5.6 to 7.4). For example, to run tests against PHP 5.6, run following:

To develop locally, use dev service. Following will install Composer dependencies:

License

MIT licensed, see LICENSE file.