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Showing posts from December 18, 2011

Read a File line by line in Shell

I've used a few techniques for this kind of reading but gets failed until I've read this fine blog . http://www.bashguru.com/2010/05/how-to-read-file-line-by-line-in-shell.html this helps a lot and i have developed a trick for me. Refer to the following example to examine the script : #!/bin/bash #SCRIPT: method2.sh #PURPOSE: Process a file line by line with redirected while-read loop . FILENAME=$1 count=0 while read LINE do let count++ echo "$count $LINE" done < $FILENAME echo -e "\nTotal $count Lines read" I have passed the file in the end of the loop so i didn't need  to use pipe that is why i process the file in fastest manner and gives  the required output in a quick manner. However i can use one more thing the File Descriptors. The File Descriptors are similar to the normal file pointers however in  more analogue way.If you have used C then you will have familier with the  the default file openers in C "st

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Helm generic springboot templates

With the dramatically increasing demand for container orchestration specifically Kubernetes, demand to template K8S manifests(Json/Yaml) also came to light. To handle increasing manifests, new CRDs(Custom resource definition), etc… it became obvious that we need a package manager somewhat like yum, apt, etc… However, the nature of Kubernetes manifest is very different than what one used to have with Yum and Apt. These manifests required a lot of templates which is now supported by Helm, a tool written in GoLang with custom helm functions and pipelines. Neutral background on templating Templating has been a driver for configuration management for a long time. While it may seem trivial for users coming from Ansible, Chef, Puppet, Salt, etc…, it is not. Once one moves to Kubernetes, the very first realization is hard declarative approach that Kubernetes follows. It is difficult to make generic templating with declarative form since each application may have some unique feature and r

Allowing users to have ssh access

Allowing users to have ssh access Hi Readers, It is one of the tasks we need to complete in order to allow users to log-in into your server without compromising your security. We are going to accomplish the following tasks, 1.) Allow the users for given domain only 2.) Must allow access to a given domain 3.) Block access for a specific domain. These questions are asked in RedHat certification examination RHCE6 We are going to complete the above mention task using iptables To give proper example we are taking 192.168.20.0/255.255.255.0 as our domain and 192.168.21.0/255.255.255.0 as other domain. Assuming that your system is a fresh installation we can remove all rules previously applied. # iptables -F  The above mention command will flush all the previously applied rules. Insert a rule in your input chain by below mention command, # iptables -I INPUT -s <ip of your domain>/<subnet mask> -p <protocal tcp/udp> --dport <port> -j AC

A few useful sql functions

Start mysql in Ubuntu without having root privilege:- If you want to use mysql in Ubutu you can use following command which will use a root level privilege   $ mysql -u root -p Enter password: Welcome to the MySQL monitor.  Commands end with ; or \g. Your MySQL connection id is 147 Server version: 5.1.49-1ubuntu8.1-log (Ubuntu) When it demands to enter the password fill it with 'root' and hopefully you'll get logged in .   Last_insert_id():- (with no argument) returns the first automatically generated value that was set for an AUTO_INCREMENT column by the most recently executed INSERT statement to affect such a column. For example, after inserting a row that generates an AUTO_INCREMENT value, you can get the value like this:   mysql> SELECT LAST_INSERT_ID(); Database():- Database() method returns the current selected database and you can use it in your communication and your queries. The syntax is :   mysql>select Database (); User():- It also has syno

Hipchat and Icinga

Hipchat Notify 2.0 Hipchat notification with API 2.0 to be used with ICINGA/Nagios Table of Contents Table of Contents Author Audience Introduction Ruby Script Script used on server Service notification Host notification Change in command.conf for Icinga server Example notification Roadmap Author Shubhamkr619@gmail.com Audience System Engineers and operation engineers Introduction Change the default mail notification of Icinga server to hipchat notification using ruby code. This will allow a single place of management of all the notification and alerts across organization. Let that be service,host or business level alerts all can be managed and monitored using hipchat and hubot will give certain advantage over traditional alerting system. Proactive and reactive alerting Managed monitoring Single place of all the alerts Better communication and collaboration Integration with multiple tools in CI cycle Jenkins Chef

Istio multicluster, gotchas ....

istio.md Istio lets you connect, secure, control, and observe services. At a high level, Istio helps reduce the complexity of these deployments, and eases the strain on your development teams. It is a completely open source service mesh that layers transparently onto existing distributed applications. It is also a platform, including APIs that let it integrate into any logging platform, or telemetry or policy system. Istio’s diverse feature set lets you successfully, and efficiently, run a distributed microservice architecture, and provides a uniform way to secure, connect, and monitor microservices. In context of Vuclip istio allows us to reduce the code and environment configurations while keeping the similar or more feature sets at our disposal. Since istio is designed to bridge the gap for both development teams and SRE, it is essential to see and visualize that in practice. Istio will affect us in our ability to connect , secure(HTTPs TLS, mtls [Phase-2]), control(external comm

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