Creating a basic DAG file in Apache Airflow - Quick Revision & Summary

Recall & Review

beginner

What is a DAG in Airflow?

A DAG (Directed Acyclic Graph) is a collection of tasks organized to reflect their relationships and dependencies. It defines the workflow in Airflow.

beginner

Which Python module do you import to create a DAG in Airflow?

You import <code>airflow</code> modules like <code>from airflow import DAG</code> and operators such as <code>from airflow.operators.bash import BashOperator</code>.

beginner

What is the purpose of the default_args dictionary in a DAG file?

It sets default parameters for tasks like start date, retries, and retry delay, so you don't have to repeat them for each task.

beginner

How do you schedule a DAG to run every day at midnight?

Set the schedule_interval parameter to '0 0 * * *' or use @daily in the DAG definition.

beginner

How do you define task dependencies in a DAG?

Use the bitshift operators task1 >> task2 to say task1 runs before task2, or task2 << task1 for the same effect.

What does DAG stand for in Airflow?

A Directed Acyclic Graph

B Data Analysis Group

C Dynamic Application Generator

D Distributed Async Gateway

DAG means Directed Acyclic Graph, which is a way to organize tasks with dependencies.

Which Airflow component defines the workflow?

A Operator

B DAG

C Task Instance

D Executor

The DAG defines the workflow by organizing tasks and their order.

How do you import the BashOperator in a DAG file?

A from airflow.operators.bash import BashOperator

B import BashOperator from airflow

C from airflow import BashOperator

D import airflow.bash.BashOperator

The correct import is from airflow.operators.bash import BashOperator.

What is the purpose of the start_date in default_args?

A To specify the task retries

B To set the time tasks should finish

C To define the task owner

D To set when the DAG should start running

start_date tells Airflow when to start scheduling the DAG.

How do you make task2 run after task1?

A task1 + task2

B task2 >> task1

C task1 >> task2

D task1 & task2

Using task1 >> task2 sets task2 to run after task1.

Describe the steps to create a basic DAG file in Airflow.

Think about the order of code and what each part does.

Explain how task dependencies work in an Airflow DAG and why they are important.

Imagine tasks as steps in a recipe that must happen in sequence.