daml-dit-ddit 0.4.7

DABL DIT File Tool

daml-dit-api

API definitions for integrations and other sorts of packages to be hosted by DABL. This contains the following:

• The definition for the package metadata format
• The call API for integration bots
• A framework for simplifying the implementation of integrations

Package Metadata

At their core, DIT files are ZIP archives that follow a specific set of conventions regarding their content. The most important of these conventions is the presence of a YAML metadata file at the root of the archive and named dabl-meta.yaml. This metadata file contains catalog information describing the contents of the DIT, as well as any packaging details needed to successfully deploy a DIT file into DABL. An example of a deployment instruction is a subdeployment. A subdeployment instructs DABL to deploy a specific subfile within the DIT file. A DIT file that contains an embedded DAR file could use a subdeployment to ensure that the embedded DAR file is deployed to the ledger when the DIT is deployed. In this way, a DIT file composed of multiple artifacts (DARs, Bots, UI's, etc.) can be constructed to deploy a set of artifacts to a single ledger in a single action.

Integrations

Integrations are a special case of DIT file that are augmented with the ability to run as an executable within a DABL cluster. This is done by packaging Python DAZL bot code into an executable ZIP using PEX and augmenting tha resulting file with the metadata and other resources needed to make it a correctly formed DIT file.

Logically speaking, DABL integrations are DAZL bots packaged with information needed to fit them into the DABL runtime and user interface. The major functional contrast between a DABL integration and a Python Bot is that the integration has the external network access needed to connect to an outside system and the Python Bot does not. Due to the security implications of running within DABL with external network access, integrations can only be deployed with the approval of DA staff.

Developing Integrations

The easiest way to develop an integration for DABL is to use the framework library bundled within this API package. The integration framework presents a Python API closely related to the DAZL bot api and ensures that integrations follow the conventions required to integrate into DABL. The framework parses ledger connection arguments, translates configuration metadata into a domain object specific to the integration, and exposes the appropriate health check endpoints required to populate the DABL integration user interface.

Unless you know exactly what you are doing and why you are doing it, use the framework.

Locally Running an integration DIT.

Because they can be directly executed by a Python interpreter, integration DIT files can be run directly on a development machine like any other standalone executable. By convention, integrations accept a number of environment variables that specify key paramaters. Integrations built with the framework use defaults for these variables that connect to a default locally configured sandbox instance.

Available variables include the following:

Variable	Default	Purpose
DABL_HEALTH_PORT	8089	Port for Health/Status HTTP endpoint
DABL_INTEGRATION_METADATA_PATH	'int_args.yaml'	Path to local metadata file
DABL_INTEGRATION_TYPE_ID		Type ID for the specific integration within the DIT to run
DABL_LEDGER_ID	'cloudbox'	Ledger ID for local ledger
DABL_LEDGER_URL	http://localhost:6865	Address of local ledger gRPC API

Several of these are specifically of note for local development scenarios:

• DABL_INTEGRATION_INTEGRATION_ID - This is the ID of the integration that would normally come from DABL itself. This needs to be provided, but the specific value doesn't matter.
• DABL_INTEGRATION_TYPE_ID - DIT files can contain definitions for multiple types of integrations. Each integration type is described in a IntegrationTypeInfo block in the dabl-meta.yaml file and identified with an id. This ID needs to be specified with DABL_INTEGRATION_TYPE_ID, to launch the appropriate integration type within the DIT.
• DABL_INTEGRATION_METADATA_PATH - Integration configuration parameters specified to the integration from the console are communicated to the integration at runtime via a metadata file. By convention, this metadata file is named int_args.yaml and must be located in the working directory where the integration is being run.
• DABL_HEALTH_PORT - Each integration exposes health and status over a healthz HTTP resource. http://localhost:8089/healthz is the default, and the port can be adjusted, if necessary. (This will be the case in scenarios where multiple integrations are being run locally.) Inbound webhook resources defined with webhook handlers will also be exposed on this HTTP endpoint.

Integration Configuration Arguments

Integrations accept their runtime configuration parameters through the metadata block of a configuration YAML file. This file is distinct from dabl_meta.yaml, usually named int_args.yaml and by default should be located in the working directory of the integration. A file and path can be explicitly specified using the DABL_INTEGRATION_METADATA_PATH environment variable.

The format of the file is a single string/string map located under the metadata key. The keys of the metadata map are the are defined by the fields specified for the integration in the DIT file's dabl-meta.yaml and the values are the the configuration paramaters for the integration.

"metadata":
  "interval": "1"
  "runAs": "ledger-party-f18044e5-6157-47bd-8ba6-7641b54b87ff"
  "targetTemplate": "9b0a268f4d5c93831e6b3b6d675a5416a8e94015c9bde7263b6ab450e10ae11b:Utility.Sequence:Sequence"
  "templateChoice": "Sequence_Next"