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Added quick start guide to use cosmos in airflow workflow for dbt transformations. #211

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= Execute dbt teradata transformation jobs in Apache Airflow using Astronomer Cosmos library
:experimental:
:page-author: Satish Chinthanippu
:page-email: satish.chinthanippu@teradata.com
:page-revdate: July 15th, 2024
:description: Execute dbt teradata transformation jobs in Apache Airflow using Astronomer Cosmos library
:keywords: data warehouses, compute storage separation, teradata, vantage, cloud data platform, object storage, business intelligence, enterprise analytics, airflow, queries, dbt, cosmos, astronomer
:dir: execute-dbt-teradata-transformations-in-airflow-with-cosmos
:auxdir: execute-dbt-teradata-transformations-in-airflow-with-cosmos

== Overview

This tutorial demonstrates how to install Apache Airflow on a local machine, configure the workflow to use dbt teradata to run dbt transformations using the astronomer cosmos library, and run it against a Teradata Vantage database. Apache Airflow is a task scheduling tool that is typically used to build data pipelines to process and load data. https://astronomer.github.io/astronomer-cosmos/[Astronomer cosmos] library simplifies orchestrating dbt data transformations in Apache Airflow. Using Cosmos, allows running dbt Core projects as Apache Airflow DAGs and Task Groups with a few lines of code.
In this example, we will explain how to use astronomer cosmos to run dbt transformations in airflow against Teradata Vantage database.

NOTE: Use `https://learn.microsoft.com/en-us/windows/wsl/install[The Windows Subsystem for Linux (WSL)]` on `Windows` to try this quickstart example.

== Prerequisites
* Access to a Teradata Vantage instance, version 17.10 or higher.
+
include::ROOT:partial$vantage_clearscape_analytics.adoc[]
* Python 3.8, 3.9, 3.10 or 3.11 and python3-env, python3-pip installed.
+
[tabs, id="python_install"]
====
Linux::
+
[source,bash]
----
sudo apt install -y python3-venv python3-pip
----
WSL::
+
[source,bash]
----
sudo apt install -y python3-venv python3-pip
----
macOS::
+
[source,bash]
----
brew install python
----
Refer https://docs.python-guide.org/starting/install3/osx/[Installation Guide] if you face any issues.
====

== Install Apache Airflow and Astronomer Cosmos
1. Create a new python environment to manage airflow and its dependencies. Activate the environment:
+
NOTE: This will install Apache Airflow as well.
+
[source, bash]
----
python3 -m venv airflow_env
source airflow_env/bin/activate
pip install "astronomer-cosmos"
----

+
2. Install the Apache Airflow Teradata provider
+
[source, bash]
----
pip install "apache-airflow-providers-teradata"
----
3. Set the AIRFLOW_HOME environment variable.
+
[source, bash]
----
export AIRFLOW_HOME=~/airflow
----

== Install dbt
1. Create a new python environment to manage dbt and its dependencies. Activate the environment:
+
[source, bash]
----
python3 -m venv dbt_env
source dbt_env/bin/activate
----
2. Install `dbt-teradata` and `dbt-core` modules:
+
[source, bash]
----
pip install dbt-teradata dbt-core
----

== Setup dbt project

1. Clone the jaffle_shop repository and cd into the project directory:
+
[source, bash]
----
git clone https://github.com/Teradata/jaffle_shop-dev.git jaffle_shop
----
2. Make a new folder, dbt, inside $AIRFLOW_HOME/dags folder. Then, copy/paste jaffle_shop dbt project into $AIRFLOW_HOME/dags/dbt directory
+
[source, bash]
----
mkdir -p $AIRFLOW_HOME/dags/dbt/
cp -r jaffle_shop $AIRFLOW_HOME/dags/dbt/
----

== Configure Apache Airflow
1. Switch to virtual environment where Apache Airflow was installed at <<Install Apache Airflow and Astronomer Cosmos>>
+
[source, bash]
----
source airflow_env/bin/activate
----
2. Configure the listed environment variables to activate the test connection button, preventing the loading of sample DAGs and default connections in Airflow UI.
+
[source, bash]
export AIRFLOW__CORE__TEST_CONNECTION=Enabled
export AIRFLOW__CORE__LOAD_EXAMPLES=false
export AIRFLOW__CORE_LOAD_DEFAULT_CONNECTIONS=false

3. Define the path of jaffle_shop project as an environment variable `dbt_project_home_dir`.
+
[source, bash]
----
export dbt_project_home_dir=$AIRFLOW_HOME/dags/dbt/jaffle_shop
----
4. Define the path to the virtual environment where dbt-teradata was installed as an environment variable `dbt_venv_dir`.
[source, bash]
export dbt_venv_dir=/../../dbt_env/bin/dbt
+
NOTE: You might need to change `/../../` to the specific path where the `dbt_env` virtual environment is located.

== Start Apache Airflow web server
1. Run airflow web server
+
[source, bash]
----
airflow standalone
----
2. Access the airflow UI. Visit https://localhost:8080 in the browser and log in with the admin account details shown in the terminal.
+
image::{dir}/execute-dbt-teradata-cosmos-airflow.png[Airflow Password,align="left" width=75%]

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Add image of the terminal

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Added.

== Define Apache Airflow connection to Vantage

1. Click on Admin - Connections
2. Click on + to define new connection to Teradata Vantage instance.
3. Define new connection with id `teradata_default` with Teradata Vantage instance details.
* Connection Id: teradata_default
* Connection Type: Teradata
* Database Server URL (required): Teradata Vantage instance hostname to connect to.
* Database: jaffle_shop
* Login (required): database user
* Password (required): database user password

== Define DAG in Apache Airflow
Dags in airflow are defined as python files. The dag below runs the dbt transformations defined in the `jaffle_shop` dbt project on a Teradata Vantage system using cosmos.Copy the python code below and save it as `airflow-cosmos-dbt-teradata-integration.py` under the directory $AIRFLOW_HOME/dags.

[source, python]
----
import os
from datetime import datetime

from airflow import DAG
from cosmos import DbtTaskGroup, ProjectConfig, ProfileConfig, ExecutionConfig
from cosmos.profiles import TeradataUserPasswordProfileMapping

PATH_TO_DBT_VENV = f"{os.environ['dbt_venv_dir']}"
PATH_TO_DBT_PROJECT = f"{os.environ['dbt_project_home_dir']}"


execution_config = ExecutionConfig(
dbt_executable_path=PATH_TO_DBT_VENV,
)
profile_config = ProfileConfig(
profile_name="generated_profile",
target_name="dev",
profile_mapping=TeradataUserPasswordProfileMapping(
conn_id="teradata_default",
),
)
with DAG(
dag_id="execute_dbt_transformations_with_cosmos",
max_active_runs=1,
max_active_tasks=10,
catchup=False,
start_date=datetime(2024, 1, 1),

) as dag:
transform_data = DbtTaskGroup(
group_id="transform_data",
project_config=ProjectConfig(PATH_TO_DBT_PROJECT),
profile_config=profile_config,
execution_config=execution_config,
default_args={"retries": 2},
)
----

== Load DAG

When the dag file is copied to $AIRFLOW_HOME/dags, Apache Airflow displays the dag in UI under DAGs section. It will take 2 to 3 minutes to load DAG in Apache Airflow UI.

== Run DAG

Run the dag as shown in the image below.

image::{dir}/airflow-dag.png[Run dag,align="left" width=75%]

== Summary

In this quick start guide, we explored how to utilize Astronomer Cosmos library in Apache Airflow to execute `dbt transformations` against a Teradata Vantage instance.

== Further reading
* link:https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/dags.html[Apache Airflow DAGs reference]
* link:https://astronomer.github.io/astronomer-cosmos/[Benefits of Cosmos]
* link:https://astronomer.github.io/astronomer-cosmos/profiles/TeradataUserPassword.html[Teradata Cosmos Profile]
* link:https://learn.microsoft.com/en-us/windows/wsl/install[Install WSL on windows]