A really quick and dirty script to parse log files, look for errors, and send a report to multiple email addresses

gistfile1.rb

#!/usr/bin/env ruby
require 'date'
require 'net/smtp'

# Who to send the report to
RECIPIENTS = %w( me@example.com )

# Who the message will be sent as
FROM_ADDRESS = "root@example.com"

# The log files to parse and what to look for
# Note: formats are regular expressions
LOG_FILES = [
	{ :path => "/var/log/rsnapshot",
	  :format => "[%d/%b/%Y:%H:%M:%S]",
	  :error_format => "ERROR"
	},
	{ :path => "/var/log/mail.err",
	  :format => "%b %d %H:%M:%S",
	  :error_format => "(fatal|panic|error)"
	}
]

since_date = DateTime.now - 1
gmt_offset = Rational(Time.now.gmt_offset / 3600, 24)
errors_detected = false

LOG_FILES.each do |log_file|
  messages = []
  File.open(log_file[:path], 'r') do |file|
    begin
      date = DateTime.strptime(line, log_file[:format]).newof(gmt_offset) - gmt_offset
      if date > since_date
        messages << line
        errors_detected = true if line.match(/#{log_file[:error_format]}/)
      end
    rescue ArgumentError
    end
  end
  log_file[:messages] = messages
end

RECIPIENTS.each do |recipient|
  subject = "Server Status " + errors_detected ? "ERROR", "OK"
  body = ""
LOG_FILES.each do |log_file|
    body += "<h2>Log: #{log_file[:path]}</h2>\n"
    body += "<ul>\n"
    for message in log_file[:messages] do
      style = message.match(/#{log_file[:error_format]}/) ? " style='color: red;'" : ""
      body += "<li#{style}>#{message}</li>\n"
    end
    body += "</ul>\n"
  end

  msg = <<END_OF_MESSAGE
From: Server Status <#{FROM_ADDRESS}>
To: <#{recipient}>
MIME-Version: 1.0
Content-type: text/html
Subject: #{subject}

#{body}
END_OF_MESSAGE
  Net::SMTP.start('localhost') do |smtp|
    smtp.send_message msg, FROM_ADDRESS, recipient
  end
end