session-18.txt

ansible shell vs ansible command module
----------------------------------------
shell module
command module

shell module --> it will use shell environment, means we can use redirections >, pipes | and other shell variables

command module --> it will just run the commands, but can't use shell environment like > , pipe | or variables.

if a simple plain command with out variables, redirections, pipes, etc. we can use command module..

if you want to run shell script inside ansible or complex commands with redirections then we can use shell module

ansible.builtin.user -> works for all distros

useradd/adduser -->

if we use ansible modules we can automatically get idempotency nature..

src: # by default ansible checks in ansible server
dest:

1. make the connection
2. import the data

troubleshoot
--------------------

DB
---
check mysql service is running or not
systemctl status mysqld

check port no 3306 is opened or not
netstat -lntp

check you are able to connect mysql or not
mysql -h db.daws78s.online -u root -pExpenseApp@1

ps -ef | grep mysql
mysql process is running or not

Backend
--------
check backend service is running
systemctl status backend

check port no 8080 is running or not
netstat -lntp

check you are able to connect mysql or not
telnet db.daws78s.online 3306

check mysql data is imported
mysql -h db.daws78s.online -u root -pExpenseApp@1
show databases;
use transactions;
show tables;

ps -ef | grep expense

frontend
-----------
systemctl status nginx
netstat -lntp --> port no 80

telnet backend.daws78s.online 8080

system/os package --> mysql(c language)
ansible --> PyMYSQL (python)
nodejs backend --> mysql(nodejs package)
can java application use mysql nodejs library? no