Author Archives: razvan

Clear swap space and move to RAM


Google Chrome UI extremely large

Today I updated google-chrome-stable to version 43.0.2357.124-1 and I had an unpleasant surprise. Everything was looking bigger: the top bar, the bookmark bar, the menus, the font on the website. Something like this:

Screenshot from 2015-06-11 09:50:04

It seems the fix is to start the chrome browser with –force-device-scale-factor option.

Screenshot from 2015-06-11 09:55:01

And the result is:

Screenshot from 2015-06-11 09:57:14

The UI looks again like before.

Create a Cassandra cluster with OpsCenter on Amazon EC2

Today I played a little with Cassandra on Amazon EC2. It was a very user friendly and pleasant experience to deploy a cluster with 2 nodes in one region using DataStax OpsCenter.

First I started a m1.small instance in Amazon EC2 where I installed OpsCenter. For this I chose Centos 6, the official AMI. Before starting to install OpsCenter, we need to configure the firewall in order to be able to access it. In AWS console, under the Security group, there is “CentOS 6 -x86_64- – with Updates-6 – 2014-09-29-AutogenByAWSMP-“. We need to righ-click on it and Edit inbound rules. Here we add a new Custom TCP Rule with port 8888 and the Source IP: My IP.

Anyway, I noticed that the instance has also an iptables firewall and the port 8888 is not open. So, on the instance I did:

Now, we can install OpsCenter. All you need to do is to follow the installation guide for RPM package from DataStax:

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Install SSL certificate for Nginx

Recently I bought an SSL certificate for this blog from MegaSSLStore. My website is hosted on a FreeBSD machine and served by Nginx web server. In order to install the certificate on this machine, I downloaded from MegaSSLStore the certificate and CSR+private key and I copied them on my server in /usr/local/etc/nginx/ssl

Because I have an .crt certificate and also a ca-bundle I need to combine these two files in one certificate:

After this, I changed the nginx website configuration file, in order to redirect all the traffic that is coming on http (port 80) on https (port 443).

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Monitor an error log with python and RabbitMQ

Nowadays there are many professional solutions to monitor your application for the errors. Some web frameworks have even build-in tools or support plugins to catch the programming exceptions and act accordingly.

Anyway, I wanted just to build a simple proof of concept how to monitor the web server error file and, when an event occurs and the file is changed, the monitoring script should send out an email. To monitor the log file I used pyinotify python module. This is an implementation on top of inotify, offering an easy interface to interact with the changes of the filesystem.

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