Log inspection and troubleshooting in Apache Airflow - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to view the latest logs of a task instance in Airflow CLI.

Apache Airflow

airflow tasks [1] my_dag my_task 2023-06-01

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

Arun

Btrigger

Clist

Dlogs

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'run' instead of 'logs' to view logs.

Confusing 'list' or 'trigger' commands with logs.

The airflow tasks logs command shows logs for a specific task instance.

2fill in blank

medium

Complete the code to check the status of all tasks in a DAG run using Airflow CLI.

Apache Airflow

airflow tasks [1] my_dag 2023-06-01

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

Alist

Bstate

Clogs

Dclear

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'logs' which shows logs, not task list.

Using 'state' which is not a valid subcommand.

The airflow tasks list command shows all tasks and their status for a DAG run.

3fill in blank

hard

Fix the error in the command to clear task instances for a DAG run.

Apache Airflow

airflow tasks [1] my_dag my_task 2023-06-01 --yes

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Aremove

Bdelete

Cclear

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'delete' or 'remove' which are not valid Airflow commands.

Using 'reset' which does not exist.

The correct subcommand to clear task instances is clear.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that filters logs by task state.

Apache Airflow

filtered_logs = {task_id: log for task_id, log in logs.items() if task_states[task_id] [1] [2]

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A==

B'success'

C'failed'

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' causes wrong filtering.

Filtering for 'failed' instead of 'success'.

This comprehension keeps logs where the task state equals 'success'.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps task IDs to logs for failed tasks.

Apache Airflow

failed_logs = { [1]: [2] for [3], [2] in logs.items() if task_states[[1]] == 'failed' }

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

Atask_id

Blog

Dtask

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent variable names causing errors.

Mixing up keys and values in the comprehension.

This comprehension creates a dictionary of logs for tasks that failed, using task IDs as keys.

Practice

1. What is the main purpose of inspecting logs in Airflow tasks?

easy

A. To schedule new DAG runs

B. To change the task's code automatically

C. To understand what happened during task execution step-by-step

D. To delete old DAGs from Airflow

Solution

1. Step 1: Understand what logs represent in Airflow

   Logs record the detailed events and outputs of each task run, showing what happened inside the task.

2. Step 2: Identify the purpose of inspecting logs

   Inspecting logs helps to see the step-by-step execution and find errors or confirm success.

3. Final Answer:

   To understand what happened during task execution step-by-step -> Option C

4. Quick Check:

   Logs show task execution details = A [OK]

Hint: Logs tell the story of task steps and errors [OK]

Common Mistakes:

• Thinking logs change task code
• Confusing logs with scheduling
• Believing logs delete DAGs

2. Which command correctly shows logs for a task named process_data in DAG daily_report for date 2024-06-01?

easy

A. airflow tasks logs daily_report process_data 2024-06-01

B. airflow logs show daily_report process_data 2024-06-01

C. airflow show logs daily_report process_data 2024-06-01

D. airflow task logs daily_report process_data 2024-06-01

Solution

1. Step 1: Recall the correct airflow CLI syntax for logs

   The correct command is airflow tasks logs <dag_id> <task_id> <execution_date>.

2. Step 2: Match the command with given task and date

   airflow tasks logs daily_report process_data 2024-06-01 matches the syntax exactly with correct order and spelling.

3. Final Answer:

   airflow tasks logs daily_report process_data 2024-06-01 -> Option A

4. Quick Check:

   Correct airflow logs command = A [OK]

Hint: Use 'airflow tasks logs DAG task date' exactly [OK]

Common Mistakes:

• Swapping 'tasks' and 'logs' words
• Using 'show' or 'task' incorrectly
• Wrong command order

3. You run airflow tasks logs sales_report generate_summary 2024-06-02 and see an error about missing file. What does this log output indicate?

medium

A. The task succeeded without issues

B. The DAG did not run on that date

C. The Airflow scheduler is down

D. The task failed because it could not find a required file

Solution

1. Step 1: Analyze the log error message about missing file

   An error about a missing file means the task tried to access a file that does not exist or is not reachable.

2. Step 2: Understand the implication for task status

   This error causes the task to fail because it cannot complete its work without the file.

3. Final Answer:

   The task failed because it could not find a required file -> Option D

4. Quick Check:

   Missing file error means task failure = C [OK]

Hint: Missing file error means task failure [OK]

Common Mistakes:

• Assuming task succeeded despite error
• Confusing DAG run status with task logs
• Thinking scheduler status is shown in task logs

4. You try to view logs with airflow tasks logs my_dag my_task 2024-06-05 but get a 'No logs found' message. What is the most likely cause?

medium

A. The DAG is paused

B. The task has not run yet for that date

C. Airflow is not installed

D. The command syntax is incorrect

Solution

1. Step 1: Understand what 'No logs found' means in Airflow

   This message usually means no logs exist because the task has not executed for the given date.

2. Step 2: Check other options for plausibility

   The command syntax is correct, Airflow installed is unrelated, and paused DAGs still keep logs from past runs.

3. Final Answer:

   The task has not run yet for that date -> Option B

4. Quick Check:

   No logs means no task run yet = D [OK]

Hint: No logs means task not run yet for that date [OK]

Common Mistakes:

• Assuming command syntax error
• Thinking Airflow is missing
• Confusing paused DAG with no logs

5. You want to troubleshoot why your Airflow task data_cleanup in DAG weekly_maintenance fails intermittently. Which approach best helps you find the root cause using logs?

hard

A. Check logs for multiple recent runs to find patterns of failure

B. Delete all logs to force fresh logging

C. Restart Airflow scheduler without checking logs

D. Change the DAG schedule to run more often

Solution

1. Step 1: Understand the goal of troubleshooting intermittent failures

   Intermittent failures require comparing multiple runs to see when and why failures happen.

2. Step 2: Identify the best log inspection method

   Checking logs from several recent runs helps spot patterns or recurring errors causing failure.

3. Final Answer:

   Check logs for multiple recent runs to find patterns of failure -> Option A

4. Quick Check:

   Compare multiple logs to find failure patterns = B [OK]

Hint: Compare logs from several runs to spot failure patterns [OK]

Common Mistakes:

• Deleting logs loses important info
• Restarting scheduler ignores root cause
• Changing schedule doesn't fix errors