Prerequisites and Requirements

Relevant source files

The following files were used as context for generating this wiki page:

• pyproject.toml
• README.md
• dbt_ext/extension.py
• dbt_ext/main.py
• dbt_ext/dbt_files/bundle/transform/dbt_project.yml
• dbt_ext/dbt_files/profiles/postgres/profiles.yml
• dbt_ext/pass_through.py

This document outlines the software dependencies, environment configurations, and project structures required to deploy and operate the meltano-dbt-ext utility extension. The extension serves as a wrapper for dbt (data build tool) within the Meltano ecosystem, necessitating specific Python environments and environment variables to function correctly.

Sources: pyproject.toml:1-10, dbt_ext/extension.py:34-45

Software Dependencies

The extension is built using the Meltano Extension Developer Kit (EDK) and requires a modern Python environment.

Core Requirements

• Python: Version 3.10 or higher is required.
• Meltano EDK: The extension depends on meltano.edk (versions 0.5 to <0.7).
• CLI Framework: Uses typer (approximately version 0.26.0) for the command-line interface.
• Configuration: PyYAML (version 6.0.0 or higher) for parsing dbt project and profile files.

Sources: pyproject.toml:10-17

Development Requirements

For contributors or those running the test suite, the following packages are required:

• pytest >= 9
• ruff >= 0.15
• pre-commit >= 3

Sources: pyproject.toml:23-27

Environment Configuration

The extension's behavior is primarily driven by environment variables. These variables control how the extension locates dbt files and which database adapter it uses.

Mandatory Environment Variables

The dbt extension class will raise a MissingProfileTypeError if the primary configuration variable is not found during initialization.

Variable	Description	Default / Requirement
DBT_EXT_TYPE	Defines the dbt adapter/profile type (e.g., postgres, snowflake, bigquery).	Mandatory
DBT_PROJECT_DIR	The filesystem path to the dbt project.	transform
DBT_PROFILES_DIR	The filesystem path to the dbt profiles.yml file.	$DBT_PROJECT_DIR/profiles

Sources: dbt_ext/extension.py:38-51, README.md:16-25

Optional Execution Settings

• DBT_EXT_SKIP_PRE_INVOKE: A boolean flag (defaulting to false). When set to true, the extension skips the automatic execution of dbt clean and dbt deps before running other commands.

Sources: dbt_ext/extension.py:53-56, README.md:18-22

Architecture and Initialization Flow

The extension relies on a specific sequence to prepare the environment. When meltano invoke dbt-postgres:initialize is called, the extension bundles internal dbt templates into the project directory.

Database-Specific Requirements

Each supported dbt adapter requires specific environment variables to be mapped via profiles.yml. The extension provides templates for various backends.

PostgreSQL Example

For a postgres type, the following variables must be available in the environment to satisfy the template:

• DBT_POSTGRES_HOST
• DBT_POSTGRES_USER
• DBT_POSTGRES_PASSWORD
• DBT_POSTGRES_PORT
• DBT_POSTGRES_DBNAME
• DBT_POSTGRES_SCHEMA

Sources: dbt_ext/dbt_files/profiles/postgres/profiles.yml:6-14

Project Structure Prerequisites

The extension expects a standard dbt project layout, typically located within a transform directory. The bundled dbt_project.yml sets the following expectations for the project structure:

dbt Component	Default Path
Models	models
Tests	tests
Seeds	data
Macros	macros
Snapshots	snapshots
Packages	dbt_packages

Sources: dbt_ext/dbt_files/bundle/transform/dbt_project.yml:10-23

Execution Requirements

When a command is invoked, the extension performs a pre-invoke check unless explicitly skipped.

Summary

To use meltano-dbt-ext, the system must have Python 3.10+ installed and the environment must provide DBT_EXT_TYPE to select the appropriate database profile. Users must run the initialize command to deploy the necessary dbt project files and profile templates. Once initialized, the extension manages dbt dependencies and execution by wrapping the standard dbt CLI and providing passthrough capabilities via dbt_invoker.

Sources: pyproject.toml:9-10, README.md:209-214, dbt_ext/pass_through.py:12-19