Tag Archives: scripting

cfengine – some useful examples / or how I learn’t about the bomb and tried Puppet instead / salt?

Building on the initial post about cfengine we’re going to try out some things that may actually be useful.

My goal would be to make /etc/resolv.conf identical between all the machines.

The server setup is the lustre cluster we built in a previous post.

In this post you’ll first see two attempts at getting cfengine and then puppet to do my bidding until success was finally accomplished with salt.

Cfengine

Set up name resolution to be identical on all machines.

http://blog.normation.com/2011/03/21/why-we-use-cfengine-file-editing/

Thought about

Make oss1 and client1 not get the same promises.

Perhaps some kind of rule / IF-statement in the promise?

Cfengine feels archaic. Think editing named/bind configs are complicated? They are not even close to setting up basic promises in cfengine.

Puppet ->

http://puppetlabs.com/

CentOS 6 Puppet Install

vi /etc/yum.repos.d/puppet.repo
pdcp -w oss1,client1 /etc/yum.repos.d/puppet.repo /etc/yum.repos.d/puppet.repo

Sign certificates:

puppet cert list
puppet cert sign 
sudo puppet cert sign --all

For puppet there’s a dashboard. This sounds interesting. Perhaps I won’t have to write these .pp files which at a glancelooks scarily similar to the cfengine promises.

yum install puppet-dashboard mysqld

service start mysqld

set mysqld password

create databases (as in the database.yml file)

after this I didn’t get much further… But I did get the web-server up. Although it was quite empty…

salt

Easy startup instructions here for getting a parallel shell going:

After it’s set up you can run a bunch of built-in special commands, see the help section about modules.

salt ‘*’ sys.doc|less

will give you all the available modules you use :)

Want to use it for configuration management too? Check out the ‘states‘ section.

What looks bad with salt is that it’s a quite new (first release in 2011)

Salt is a very common word so it makes googling hard. Most hits tend to be about cryptography or cooking.

To distribute (once) the resolv.conf do you run this on the admin-server: salt-cp ‘*’ /etc/resolv.conf /etc/resolv.conf

On to states to make sure that the resolv.conf stays the same:

  1. uncomment the defaults in the master-file about file_roots and restart the salt-master service
  2. create /srv/salt and ln -s /etc/resolv.conf /srv/salt/resolv.conf
  3. create a /srv/salt/top.sls and a /srv/salt/resolver.sls

 

In top.sls put:

base:
 '*':
   - resolver

In resolver.sls put:

/etc/resolv.conf:
 file:
  - managed
  - source: salt://resolv.conf

Then run: salt ‘*’ salt.highstate

How to get this to run every now and then? Setting up a cronjob works.

Haven’t been able to find a built-in function to accomplish this but then again, all I’m doing here is scratching at the surface so it’s working and I’m happy :)

Script To Check For an Update on a Web Page

Hey!

This is used for me on my Linux workstation to get a notification if there is a new spotify release whenever I open a new terminal.. It would be applicable for other (probably also simple) pages that aren’t updated frequently.

Reason: http://repository.spotify.com/pool/non-free/s/spotify/

I wanted to see if there was a new spotify release for Linux/QT.

Method: The URL is above – but what if I do not want to go there every day and get disappointed?

Way nicer to have a script do it for me.

This script saves the index.html from the URL above of each day.

Then each day when it downloads the .html it checks if it’s different from yesterday.

This has its limitations, if there is an update in the weekend I will never know.

The script should check the last x amount of days and if any of them are different from today it should tell me. The script checks if any of the files are different from today, if so, it will write something into another file. The script then checks if this file is non-empty, if it has data in it, it will write to this other file that. Tada. :p

If it is, then it will write to a file that is referenced in $HOME/.bashrc.

The layout of the blog doesn’t like really long lines in <pre>, but you can select below and only get the post (and not the stuff on the right side).

spot_check.sh:

#!/bin/sh

dat1=$(date +%Y.%m.%d)
daty=$(perl -MPOSIX=strftime -le 'print strftime "%Y.%m.%d",localtime (time - 86400)')
dat2=$(perl -MPOSIX=strftime -le 'print strftime "%Y.%m.%d",localtime (time - 172800)')
dat3=$(perl -MPOSIX=strftime -le 'print strftime "%Y.%m.%d",localtime (time - 259200)')
dat4=$(perl -MPOSIX=strftime -le 'print strftime "%Y.%m.%d",localtime (time - 345600)')
dat5=$(perl -MPOSIX=strftime -le 'print strftime "%Y.%m.%d",localtime (time - 432000)')

path="$HOME/Downloads/Spotify/saved"
out="$HOME/Downloads/Spotify/diff.log"
bout="$HOME/.spotcheck"
wget -q http://repository.spotify.com/pool/non-free/s/spotify/ -O $path/$dat1.html

diff -q $path/$dat1.html $path/$daty.html > $out
diff -q $path/$dat1.html $path/$dat2.html >> $out
diff -q $path/$dat1.html $path/$dat3.html >> $out
diff -q $path/$dat1.html $path/$dat4.html >> $out
diff -q $path/$dat1.html $path/$dat5.html >> $out

if [[ -s $out ]] ; then
echo $out "is not empty";
echo "#!/bin/sh" > $bout;
echo "echo new spotify release" >> $bout;
chmod +x $bout;
else
echo $out "is empty";
echo "No new spotify release.";
rm $bout;
fi;

Crontab (daily at 0915):

15 09 * * * /bin/bash /home/username/Downloads/Spotify/spot_check.sh 2>&1

.bashrc:

if [ -f ~/.spotcheck ]; then
cd $HOME
./.spotcheck
fi