DevOps Learning

  మన లక్ష్యం ఎప్పుడు కూడా నిన్నటి మీద ఈ రోజు బెటర్ ఆవాలి అని ఉండాలి తప్ప ఒక్కసారిగా ఒక్కటి నుండి వందకి వెళ్ళాలి అని ఉండకూడదు. అద్రుష్టం వల్ల కొన్ని కలసివచ్చిన అవి ఎక్కువ కాలం నిలబడవు. మన కష్టాన్ని మాత్రమే నమ్ముకోవాలి. అసలు నొప్పి లేకుండా వచ్చిన వాటిల్లో సంతృప్తి ఉండదు

Configuration management tool :  Puppet, Chef, Rundesk, Ansible, etc   There are two architecture in CM tools : push and pull Suppose there is a DTDC courier from Delhi --> to Hyderabad In Hyd DTDC we go to Hyd DTDC and check for courier     (this is called pull) We sit in home, whenever courier comes to DTDC, they deliver to us (this is called  pull) ( Example : the notification that we receive are called push notifications because these notifications are pushed from the server to our devices, if we login to facebook and see the posts it is called pull) Pull disadvantages :  causing more traffice on road --> more traffic in internet Unnecessary resource waste time, fuel, etc. --> bandwidth, power resources  cost Push: save everything, ssh protocol Ansible is push based architecture, so it avoids the disadvantages in pull based architecture. So Ansible is more popular than other pull based architectures like Chef, puppet, Rundesk etc.

Q&A

Disadvantages of shell script Not idempotent     -write custom code to make it idempotent Error handling     -- we need to write code to check the errors Homogeneous      --only works in specific distro Not scalable when to many servers syntax is not easy to understand Still shell scripting is powerful when we have minimum number of servers Configuration management : take plain server without anything installed install app runtime and few p ackages create users and folders, download code, install dependencies, creating systemctl services,  copying config files we can use S hell scripting to do configuration management in few servers. So to do Configuration management in many servers we choose Ansible instead of shell scripting

 kubectl get nodes  --> gives one master and Other worker nodes.

 Jenkins Kubernetes Integration :

 Linux Folder Structure /bin     (binaries)   --> essential commands are here ls,cat, grep etc /sbin      ( system binaries)    --> admin commands, reboot, iptables etc. /boot              --> (contains linux kernal ) when linux server is started, it refers to the boot directory. /etc      (extra configuration) --> system configuration files eg: nginx, ssh configurations etc. /dev     ( device)      --> monitor, terminal, keyboard, mouse, printer /home      (home directory of users) --> all user directories are here, all user personal files and configurations files are here /lib      (libraries)      --> libraries required by OS. it  is equal to .dll in windows /lib64      (64 bit libraries) /media      (media devices) /mnt      (mount)  ...