Extempore

Dear all,

We are in the process of changing the monitoring system on part of our network from Zenoss to Nagios. This is not a Zenoss vs. Nagios debate, as both products are awesome and do the things they are designed for very well. We (Christian and myself) use a combination of Cacti for bandwith monitoring and Zenoss for server and device monitoring. Now, recently we decided to change the latter to Nagios. It is know for its “great deal of flexibility when integrating Nagios into their environment” (Galstad, 2005)

As Zenoss was configured using SNMP Informant to grab information about the MS Windows servers (available disk space, CPU load, etc) and Nagios uses NSClient++; one of the time consuming tasks was getting the client on the server (thank you domain ) and configuring each and every server on the Nagios server. I guess there should be some sort of discovery tool for Nagios, but I couldn’t directly find one.

In order to tackle the copy-pasting for a few dozen config files, and to brush up my bash scripting again, I wrote the Nagios Nsclient++ cfg maker Continue reading…

For several Ruby on Rails projects I had to come up with “similar” results. These are often results (video’s, products,places, hobbies, etc) with the greatest number of tags.

Say, you are tagging car pictures on a website, and have the following:

image1.jpg -> ["honda","s2000","convertible","black"]
image2.jpg -> ["honda","civic","blue"]
image3.jpg -> ["lexus","is300","blue"]
image4.jpg -> ["s2000","honda","convertible","silver"]
image5.jpg -> ["toyota","starlet","black"]

Seeing this, you’d know that image1.jpg and image4.jpg are similar pictures. Or rather “more similar” than , say, image1.jpg and image3.jpg. For this, I wrote below snippet of code. This goes in the model file, and can be called as “object.similar”. It returns an array of similar “things”, sorted on most similar to less similar (hence the results.reverse at the end)

For example:

  img = Image.find(params[:id])
  @similar_images = img.similar[0..10]

Will give you the 10 “most similar” images as img. Well, it gives you the files with the most similar tags.

def similar
  tags = self.tags
  results = []
  tags.each do |tag|
    results = results + tag.pictures # or tag.things, tag.products, ...
    results.delete(self)
  end

  # make array into hash
  h = Hash.new
  results.each do |r|
    h[r] = h[r].to_i + 1
  end

  # sort on values
  tmp = h.sort {|a,b| a[1]<=>b[1]}
  results = []
  tmp.each do |t|
    results << t[0]
  end

  results.reverse # return all items, products, ...
end

This was written for a new project coming up, and will be used to do better "similarities matching" for places.ae, though for the latter we also had to sort on distance. (For it's vicinity)

A small bash script I wrote to have incremental backups done on a unix server, and then pushed to a Windows File system. On the fileserver, we add this directory to the normal backup.

This is on a mail server, where emails are stored in MailDir format. We create weekly full backups on sunday, and daily incremental. This script is called daily at night from a cron job. Gotta love the scripting abilities of bash.

It might help you out, so here goes:

#!/bin/bash
# backup script is doing following items
# dump all incremental email into a backup file, gzip the backup file and
# move the file to an external file server

START_TIME=`/bin/date`
echo "backup started at: ${START_TIME}"

DOW_N=`/bin/date +"%w"` # number, 0 (sun), 1 (mon)
DOW_T=`/bin/date +"%F"`

TO_BACKUP="/opt/maildata/"
TEMP_FILE="/tmp/${DOW_T}_mail_backup.tar"
BACKUP_LOG="/tmp/mail.backup"
FILE_SERVER="/mnt/fileserver/" # mounted over SMB

# if it's a sunday, delete the incremental file and take a full backup
if [ ${DOW_N} -eq "0" ]; then
  /bin/rm ${BACKUP_LOG}
fi

/bin/tar -c -f ${TEMP_FILE} --listed-incremental=${BACKUP_LOG} ${TO_BACKUP}
/bin/gzip -f ${TEMP_FILE}
FILE_SIZE=`/bin/ls -lah ${TEMP_FILE}.gz | awk '{ print $5 }'`
/bin/mv ${TEMP_FILE}.gz ${FILE_SERVER}

## report, this goes in an email through cron
END_TIME=`/bin/date`; export END_TIME
echo "backup ended at: ${END_TIME}"
echo "data moved: ${FILE_SIZE}"