Ingest processors (grok, date, rename) in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Grok processor simulation?

Given the following Grok pattern and input string, what will be the value of the field status_code after processing?

{"grok": {"field": "message", "patterns": ["%{WORD:method} %{URIPATHPARAM:request} %{NUMBER:status_code:int}"]}}

Input message: GET /home 200

A 200

B GET

C /home

D null

💡 Hint

Look at the pattern and which part is assigned to status_code.

The Grok pattern extracts three parts: method as a word, request as a URI path, and status_code as a number. The input string ends with 200, which matches status_code.

❓ Predict Output

intermediate

What is the resulting timestamp after the date processor?

Given this date processor configuration:

{"date": {"field": "timestamp", "formats": ["yyyy-MM-dd HH:mm:ss"]}}

And the input document field timestamp with value 2024-06-15 14:30:00, what will be the resulting value of timestamp after processing?

A null

B "2024-06-15 14:30:00"

C "2024-06-15T14:30:00.000Z"

D "15-06-2024 14:30:00"

💡 Hint

The date processor converts the string to an ISO8601 timestamp.

The date processor parses the input string using the given format and converts it to the standard ISO8601 format with UTC timezone.

❓ Predict Output

advanced

What is the final document after rename processor?

Given this rename processor configuration:

{"rename": {"field": "old_field", "target_field": "new_field"}}

And the input document:

{"old_field": "value1", "other_field": "value2"}

What is the resulting document after processing?

A {"new_field": "value1", "other_field": "value2"}

B {"old_field": "value1", "new_field": "value1", "other_field": "value2"}

C {"other_field": "value2"}

D {"old_field": null, "new_field": "value1", "other_field": "value2"}

💡 Hint

The rename processor moves the value and removes the old field.

The rename processor copies the value from old_field to new_field and deletes old_field.

🔧 Debug

advanced

What error does this Grok processor configuration cause?

Consider this Grok processor configuration:

{"grok": {"field": "message", "patterns": ["%{WORD:method} %{URIPATHPARAM:request} %{NUMBER:status_code}"]}}

Input message: POST /api/data abc

What error will occur during processing?

A No error, status_code is 'abc' as string

B IndexOutOfBoundsException

C NullPointerException

D GrokParseException due to 'abc' not matching NUMBER

💡 Hint

The pattern expects a number but input has 'abc'.

The Grok processor expects the last part to be a number, but 'abc' does not match NUMBER pattern, causing a GrokParseException.

🧠 Conceptual

expert

Which processor sequence correctly extracts and renames a date field?

You receive logs with a field log_time in format dd/MM/yyyy HH:mm:ss. You want to parse it as a date and rename it to timestamp. Which sequence of processors achieves this correctly?

A [{"date": {"field": "log_time", "formats": ["dd/MM/yyyy HH:mm:ss"]}}, {"rename": {"field": "log_time", "target_field": "timestamp"}}]

B [{"rename": {"field": "log_time", "target_field": "timestamp"}}, {"date": {"field": "timestamp", "formats": ["dd/MM/yyyy HH:mm:ss"]}}]

C [{"rename": {"field": "timestamp", "target_field": "log_time"}}, {"date": {"field": "log_time", "formats": ["dd/MM/yyyy HH:mm:ss"]}}]

D [{"date": {"field": "timestamp", "formats": ["dd/MM/yyyy HH:mm:ss"]}}, {"rename": {"field": "log_time", "target_field": "timestamp"}}]

💡 Hint

Think about which field exists before and after rename.

You must rename log_time to timestamp first, then parse the date from timestamp. Doing date first on log_time then renaming works too, but the question asks for the correct sequence as given.