Log Explorer and queries in GCP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of Log Explorer in Google Cloud?

Log Explorer helps you find, view, and analyze logs from your Google Cloud resources in one place.

beginner

What is a basic component of a Log Explorer query?

A basic query includes a filter that selects logs by resource type, severity, or text content.

intermediate

How do you filter logs by severity in Log Explorer?

Use the filter expression like: severity>=ERROR to see logs with error or higher severity.

beginner

What does the 'resource.type' field represent in a Log Explorer query?

It identifies the Google Cloud resource that produced the log, like 'gce_instance' for a VM.

beginner

How can you use Log Explorer to find logs containing a specific text?

Include the text in quotes in the query, for example: "error connecting to database".

Which field would you use to filter logs by the Google Cloud resource type?

A logName

B resource.type

C severity

D timestamp

The 'resource.type' field specifies the type of Google Cloud resource that generated the log.

What does the filter expression 'severity>=WARNING' do in Log Explorer?

A Shows logs with severity exactly WARNING

B Shows logs with severity lower than WARNING

C Shows only WARNING logs

D Shows logs with severity WARNING or higher

The '>=' operator means logs with WARNING, ERROR, or CRITICAL severity will be shown.

How do you search for logs containing the phrase 'timeout error'?

A timeout error

B timeout OR error

C "timeout error"

D timeout AND error

Using quotes searches for the exact phrase 'timeout error' in the logs.

Which of these is NOT a valid Log Explorer query filter?

A timestamp = "yesterday"

B resource.type = "gce_instance"

C severity >= ERROR

D textPayload : "failed"

You cannot filter timestamp by a string like 'yesterday'; timestamps require specific date/time formats.

What does the 'logName' field represent in a log entry?

A The name of the log stream or log file

B The severity level of the log

C The resource type that generated the log

D The timestamp of the log entry

'logName' identifies the specific log stream or log file within Google Cloud Logging.

Explain how to build a basic query in Log Explorer to find error logs from Compute Engine instances.

Think about filtering by resource type and severity level.

Describe how you would search for logs containing a specific phrase and filter by time range in Log Explorer.

Combine text search with timestamp filters.

Practice

1. What is the main purpose of the Log Explorer in Google Cloud Platform?

easy

A. To manage user permissions

B. To create virtual machines

C. To search and filter logs generated by cloud resources

D. To deploy applications automatically

Solution

1. Step 1: Understand Log Explorer's role

   Log Explorer is designed to help users find specific log entries by searching and filtering logs.

2. Step 2: Compare with other options

   Creating VMs, managing permissions, and deploying apps are done by other GCP services, not Log Explorer.

3. Final Answer:

   To search and filter logs generated by cloud resources -> Option C

4. Quick Check:

   Log Explorer = Search and filter logs [OK]

Hint: Log Explorer is for logs, not for VMs or permissions [OK]

Common Mistakes:

• Confusing Log Explorer with Compute Engine
• Thinking it manages user roles
• Assuming it deploys apps automatically

2. Which of the following is the correct syntax to filter logs for entries where the severity is ERROR in Log Explorer?

easy

A. severity = "ERROR"

B. severity == "ERROR"

C. severity="ERROR"

D. severity = ERROR

Solution

1. Step 1: Recall Log Explorer filter syntax

   Log Explorer uses single equals (=) with quotes around string values.

2. Step 2: Check each option

   severity = "ERROR" uses correct syntax: single equals (=) with quotes around string values. Omitting quotes, using double equals, or missing spaces around the operator are incorrect.

3. Final Answer:

   severity = "ERROR" -> Option A

4. Quick Check:

   Use = and quotes for strings [OK]

Hint: Use = and quotes for string filters in Log Explorer [OK]

Common Mistakes:

• Using == instead of =
• Omitting quotes around string values
• Missing spaces around =

3. Given the query resource.type = "gce_instance" AND severity = "WARNING", what kind of log entries will this return?

medium

A. All logs from any resource with severity WARNING

B. Logs from Google Compute Engine instances with any severity

C. Logs from any resource with severity ERROR or WARNING

D. Logs from Google Compute Engine instances with severity WARNING

Solution

1. Step 1: Analyze the query conditions

   The query filters logs where resource.type equals "gce_instance" AND severity equals "WARNING".

2. Step 2: Understand the AND operator effect

   Both conditions must be true, so logs must be from GCE instances and have WARNING severity.

3. Final Answer:

   Logs from Google Compute Engine instances with severity WARNING -> Option D

4. Quick Check:

   AND means both conditions true [OK]

Hint: AND means both filters must match logs [OK]

Common Mistakes:

• Thinking OR is used instead of AND
• Ignoring resource.type filter
• Assuming severity includes ERROR

4. You wrote this query in Log Explorer: resource.type = "gce_instance" OR severity = "ERROR" AND timestamp > "2024-01-01T00:00:00Z". Why might this not return expected results?

medium

A. Because AND has higher precedence than OR, so the query groups incorrectly

B. Because timestamp filter syntax is invalid

C. Because severity cannot be combined with resource.type

D. Because OR operator is not supported in Log Explorer

Solution

1. Step 1: Understand operator precedence in Log Explorer

   AND has higher precedence than OR, so the query is read as resource.type = "gce_instance" OR (severity = "ERROR" AND timestamp > ...).

2. Step 2: Identify grouping issue

   This means logs with resource.type "gce_instance" are included regardless of timestamp or severity, which may not be intended.

3. Final Answer:

   Because AND has higher precedence than OR, so the query groups incorrectly -> Option A

4. Quick Check:

   AND binds tighter than OR [OK]

Hint: Use parentheses to group AND/OR conditions correctly [OK]

Common Mistakes:

• Ignoring operator precedence
• Assuming OR has higher precedence
• Thinking OR is unsupported

5. You want to find logs from Compute Engine instances that either have severity ERROR or occurred after March 1, 2024. Which query correctly expresses this in Log Explorer?

hard

A. (resource.type = "gce_instance" AND severity = "ERROR") OR timestamp > "2024-03-01T00:00:00Z"

B. resource.type = "gce_instance" AND (severity = "ERROR" OR timestamp > "2024-03-01T00:00:00Z")

C. resource.type = "gce_instance" OR severity = "ERROR" AND timestamp > "2024-03-01T00:00:00Z"

D. resource.type = "gce_instance" AND severity = "ERROR" OR timestamp > "2024-03-01T00:00:00Z"

Solution

1. Step 1: Understand the requirement

   We want logs from GCE instances where severity is ERROR or logs from GCE instances after March 1, 2024.

2. Step 2: Analyze each option's logic

   resource.type = "gce_instance" AND (severity = "ERROR" OR timestamp > "2024-03-01T00:00:00Z") groups severity and timestamp with OR inside parentheses combined with resource.type using AND, matching the requirement.

3. Step 3: Check other options

   (resource.type = "gce_instance" AND severity = "ERROR") OR timestamp > "2024-03-01T00:00:00Z" includes logs after March 1 from any resource, not just GCE instances. The remaining options lack parentheses, causing wrong precedence.

4. Final Answer:

   resource.type = "gce_instance" AND (severity = "ERROR" OR timestamp > "2024-03-01T00:00:00Z") -> Option B

5. Quick Check:

   Use parentheses to combine OR inside AND [OK]

Hint: Use parentheses to group OR inside AND correctly [OK]

Common Mistakes:

• Missing parentheses causing wrong logic
• Including timestamp filter outside resource.type scope
• Assuming OR has same precedence as AND