Default args and DAG parameters in Apache Airflow - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the default start date for the DAG.

Apache Airflow

default_args = {
    'start_date': [1]
}

Drag options to blanks, or click blank then click option'

Adatetime(2023, 1, 1)

Btimedelta(days=1)

Ctimezone('UTC')

Ddatetime.now()

Attempts:

3 left

💡 Hint

Common Mistakes

Using timedelta instead of datetime

Using datetime.now() which is dynamic

The start_date in default_args must be a datetime object specifying when the DAG should start running.

2fill in blank

medium

Complete the code to set the DAG's schedule interval to run daily.

Apache Airflow

dag = DAG(
    'example_dag',
    default_args=default_args,
    schedule_interval=[1]
)

Drag options to blanks, or click blank then click option'

A'@hourly'

BNone

C'@weekly'

D'@daily'

Attempts:

3 left

💡 Hint

Common Mistakes

Using '@hourly' or '@weekly' instead of '@daily'

Setting schedule_interval to None disables scheduling

The schedule_interval set to '@daily' makes the DAG run once every day.

3fill in blank

hard

Fix the error in setting the default retry delay to 5 minutes.

Apache Airflow

default_args = {
    'retry_delay': [1]
}

Drag options to blanks, or click blank then click option'

A5

B'5 minutes'

Ctimedelta(minutes=5)

Dtimedelta(5)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an integer directly

Using a string instead of timedelta

Using timedelta without specifying minutes

The retry_delay must be a timedelta object specifying the delay duration. Use timedelta(minutes=5) for 5 minutes.

4fill in blank

hard

Fill both blanks to create a DAG with default args and a weekly schedule.

Apache Airflow

dag = DAG(
    'weekly_dag',
    default_args=[1],
    schedule_interval=[2]
)

Drag options to blanks, or click blank then click option'

Adefault_args

B'@daily'

C'@weekly'

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using '@daily' instead of '@weekly'

Passing None for default_args

Use the default_args dictionary for default arguments and set schedule_interval to '@weekly' for weekly runs.

5fill in blank

hard

Fill all three blanks to define default args with retries and create a DAG with a monthly schedule.

Apache Airflow

default_args = {
    'start_date': [1],
    'retries': [2],
    'retry_delay': [3]
}

dag = DAG(
    'monthly_dag',
    default_args=default_args,
    schedule_interval='@monthly'
)

Drag options to blanks, or click blank then click option'

Adatetime(2024, 1, 1)

B3

Ctimedelta(minutes=10)

Dtimedelta(days=1)

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings instead of datetime or timedelta

Setting retries as string

Using timedelta without specifying minutes

Set start_date to a fixed datetime, retries to an integer count, and retry_delay to a timedelta for delay duration.

Practice

1. What is the main purpose of default_args in an Airflow DAG?

easy

A. To define the schedule interval of the DAG

B. To specify the Python version used by the DAG

C. To set common parameters like retries and owner for all tasks

D. To list all the tasks in the DAG

Solution

1. Step 1: Understand the role of default_args

   default_args is a dictionary used to set common settings for tasks, such as retries, owner, start date, etc.

2. Step 2: Differentiate from DAG parameters

   DAG parameters like schedule_interval control when the DAG runs, not task defaults.

3. Final Answer:

   To set common parameters like retries and owner for all tasks -> Option C

4. Quick Check:

   default_args = common task settings [OK]

Hint: default_args sets task defaults, not DAG schedule [OK]

Common Mistakes:

• Confusing default_args with DAG schedule_interval
• Thinking default_args lists tasks
• Assuming default_args sets Python version

2. Which of the following is the correct way to define default_args with retries set to 3 and owner as 'airflow'?

easy

A. default_args = {'retries': 3, 'owner': 'airflow'}

B. default_args = ['retries=3', 'owner=airflow']

C. default_args = (retries=3, owner='airflow')

D. default_args = retries:3, owner:'airflow'

Solution

1. Step 1: Recall Python dictionary syntax

   Python dictionaries use curly braces with key:value pairs, keys as strings and values properly quoted if strings.

2. Step 2: Check each option's syntax

   default_args = {'retries': 3, 'owner': 'airflow'} uses correct dictionary syntax. Options A, B, and D use invalid Python syntax for dictionaries.

3. Final Answer:

   default_args = {'retries': 3, 'owner': 'airflow'} -> Option A

4. Quick Check:

   Python dict = curly braces with key:value [OK]

Hint: default_args is a Python dict with keys and values [OK]

Common Mistakes:

• Using list or tuple instead of dict
• Missing quotes around string keys or values
• Using colon instead of equal sign inside dict

3. Given this DAG snippet:

default_args = {'owner': 'admin', 'retries': 2}
with DAG('example_dag', default_args=default_args, schedule_interval='@daily') as dag:
    task1 = BashOperator(task_id='task1', bash_command='echo Hello')
    task2 = BashOperator(task_id='task2', bash_command='echo World', retries=5)

What is the number of retries for task2?

medium

A. 5

B. 2

C. 0

D. Undefined, causes error

Solution

1. Step 1: Understand default_args and task-level override

   default_args sets retries=2 for all tasks unless overridden.

2. Step 2: Check task2 retries parameter

   task2 explicitly sets retries=5, which overrides the default.

3. Final Answer:

   5 -> Option A

4. Quick Check:

   Task-level retries override default_args [OK]

Hint: Task args override default_args if set [OK]

Common Mistakes:

• Assuming default_args always applies
• Thinking task2 inherits retries=2
• Confusing retries with schedule_interval

4. You wrote this DAG code:

default_args = {'owner': 'user', 'start_date': '2023-01-01'}
dag = DAG('my_dag', default_args=default_args, schedule_interval='@hourly')

But Airflow throws an error about start_date. What is the likely problem?

medium

A. owner cannot be 'user', must be 'airflow'

B. schedule_interval '@hourly' is invalid syntax

C. default_args must be passed as a list, not dict

D. start_date must be a datetime object, not a string

Solution

1. Step 1: Check start_date type requirement

   Airflow requires start_date to be a datetime object, not a string.

2. Step 2: Validate other parameters

   schedule_interval='@hourly' is valid, default_args is a dict, and owner can be any string.

3. Final Answer:

   start_date must be a datetime object, not a string -> Option D

4. Quick Check:

   start_date = datetime, not string [OK]

Hint: Use datetime objects for start_date in default_args [OK]

Common Mistakes:

• Passing start_date as string instead of datetime
• Misunderstanding schedule_interval format
• Thinking owner must be 'airflow'

5. You want a DAG to run every Monday at 9 AM starting from March 1, 2024, with tasks retrying twice on failure and owned by 'data_team'. Which default_args and DAG parameters are correct?

hard

A. default_args = {'owner': 'data_team', 'retries': 2, 'start_date': '2024-03-01 09:00'}\ndag = DAG('weekly_dag', default_args=default_args, schedule_interval='0 9 * * 1')

B. default_args = {'owner': 'data_team', 'retries': 2, 'start_date': datetime(2024, 3, 1)}\ndag = DAG('weekly_dag', default_args=default_args, schedule_interval='0 9 * * 1')

C. default_args = {'owner': 'data_team', 'retries': 2, 'start_date': datetime(2024, 3, 1, 9, 0)}\ndag = DAG('weekly_dag', default_args=default_args, schedule_interval='@daily')

D. default_args = {'owner': 'data_team', 'retries': 2, 'start_date': '2024-03-01 09:00'}\ndag = DAG('weekly_dag', default_args=default_args, schedule_interval='@weekly')

Solution

1. Step 1: Set start_date with datetime object

   Start date must be a datetime object; time can be set to midnight if not specified.

2. Step 2: Use correct cron for Monday 9 AM

   Cron '0 9 * * 1' means 9 AM every Monday, matching requirement.

3. Step 3: Check retries and owner in default_args

   Retries=2 and owner='data_team' are correctly set.

4. Final Answer:

   default_args with datetime(2024, 3, 1) and schedule_interval='0 9 * * 1' -> Option B

5. Quick Check:

   start_date datetime + cron for Monday 9 AM [OK]

Hint: Use cron '0 9 * * 1' for Monday 9 AM schedule [OK]

Common Mistakes:

• Using string for start_date
• Using '@weekly' which runs Sunday midnight
• Setting schedule_interval to '@daily' instead of Monday