log_entry_exists¶

Status:: ● Development
Category:: Linux System
Function Name:: log_entry_exists

Tests if a log file contains entries matching a specified pattern.

This test function searches log files for entries matching a specified pattern or regular expression. It supports limiting the search scope and is useful for validating system events and application logging.

Parameters¶

Parameter	Type	Description
`log_file`	string	Required. The path to the log file to search. Supports glob patterns.
`pattern`	string	Required. The pattern or regex to search for in the log file.
`max_lines`	integer	Optional. Maximum number of lines to search from the end of the file. Limits search scope for large log files.

Usage Example¶

Basic Log Pattern Search¶

tests:
  - name: test_log_entry_systemd
    function: linux.log_entry_exists
    parameter:
      log_file: '/var/log/syslog'
      pattern: 'systemd'
      max_lines: 1000
    description: "Test log_entry_exists with systemd pattern"

Pattern Not Found¶

tests:
  - name: test_log_entry_not_found
    function: linux.log_entry_exists
    expect_to_fail: true
    parameter:
      log_file: '/var/log/syslog'
      pattern: 'nonexistent-log-pattern-12345'
      max_lines: 100
    description: "Test log_entry_exists with non-existent pattern"

Application Log Validation¶

tests:
  - name: test_application_error_logged
    function: linux.log_entry_exists
    parameter:
      log_file: '/var/log/myapp/error.log'
      pattern: 'ERROR.*authentication failed'
      max_lines: 500
    description: "Test that authentication errors are logged"

Security Log Monitoring¶

tests:
  - name: test_ssh_login_logged
    function: linux.log_entry_exists
    parameter:
      log_file: '/var/log/auth.log'
      pattern: 'sshd.*Accepted password'
      max_lines: 1000
    description: "Test that SSH logins are logged"

Variable-Based Log Paths¶

variables:
  app_log:
    type: path
    value: "/var/log/nginx/access.log"
    description: "Web server access log"

tests:
  - name: test_web_requests_logged
    function: linux.log_entry_exists
    parameter:
      log_file: '{{app_log}}'
      pattern: 'GET /api/'
      max_lines: 2000
    description: "Test that API requests are logged"

Common Use Cases¶

System Event Validation: Verify that system events are properly logged to system logs
Application Error Monitoring: Check that application errors and exceptions are being logged
Security Audit Trail: Ensure security-related events like logins and access attempts are logged
Performance Monitoring: Validate that performance metrics and warnings appear in logs
Service Health Checking: Confirm that services are logging startup, shutdown, and operational events

Log Search Features¶

Pattern Matching:

Supports literal string matching
Regular expression pattern matching
Case-sensitive pattern matching

Search Optimization:

max_lines parameter limits search scope for performance
Searches from the end of the log file (most recent entries first)
Useful for large log files to avoid long search times

File Access:

Supports standard log file paths
Glob pattern support for dynamic log file names
Handles log rotation and compressed logs

Platform Requirements:

Linux operating system
Read access to specified log files
Standard file system access

Return Values¶

Success: Returns success when the pattern is found in the log file within the specified search scope
Failure: Returns failure when: - Pattern is not found in the log file - Log file exists but doesn’t contain matching entries - Search completes without finding the pattern
Execution Error: Returns execution error when: - Log file doesn’t exist or cannot be accessed - Permission denied reading the log file - File I/O errors occur during search - Invalid regular expression pattern provided

Example Results¶

# Success case
result: success
details:
  - "pattern 'systemd' found in log file /var/log/syslog"

# Failure case - pattern not found
result: failed
details:
  - "pattern 'nonexistent-log-pattern-12345' not found in log file /var/log/syslog"

# Execution error case - file not found
result: execution_error
error: "log file /var/log/missing.log does not exist"

# Execution error case - permission denied
result: execution_error
error: "Permission denied accessing log file /var/log/secure"