3.4 can't connect by Random password on Ubuntu16 about ansible-mongodb HOT 8 CLOSED

connection:
mongo 127.0.0.1:27017/admin -uroot -p123456

add user:
use admin
db.createUser({user:"root",pwd:"123456",roles:[{role:"readWrite",db:"admin"}]})

delete user:
db.system.users.remove({user:"root"})

ubuntu@ip-172-31-45-58:~$ cat /credentials/password.txt 
mongodb username:root
mongodb password:m02XeTWGAQ 

ubuntu@ip-172-31-45-58:~$ sudo su
root@ip-172-31-45-58:/home/ubuntu# cd /credentials/
root@ip-172-31-45-58:/credentials# ls
password.txt
root@ip-172-31-45-58:/credentials# ls
password.txt
root@ip-172-31-45-58:/credentials# find / -name init.sh
root@ip-172-31-45-58:/credentials# find / -name init_password.sh
root@ip-172-31-45-58:/credentials# mongodb admin -u root -p m02XeTWGAQ
No command 'mongodb' found, did you mean:
 Command 'mongod' from package 'mongodb-server' (universe)
mongodb: command not found
root@ip-172-31-45-58:/credentials# mongo admin -u root -p m02XeTWGAQ
MongoDB shell version v3.4.24
connecting to: mongodb://127.0.0.1:27017/admin
MongoDB server version: 3.4.24
2021-05-10T05:50:36.656+0000 E QUERY    [thread1] Error: Authentication failed. :
DB.prototype._authOrThrow@src/mongo/shell/db.js:1461:20
@(auth):6:1
@(auth):1:2
exception: login failed
root@ip-172-31-45-58:/credentials# 

root@ip-172-31-45-58:/credentials# mongo admin -u root -p 123456
MongoDB shell version v3.4.24
connecting to: mongodb://127.0.0.1:27017/admin
MongoDB server version: 3.4.24
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
	http://docs.mongodb.org/
Questions? Try the support group
	http://groups.google.com/group/mongodb-user
Server has startup warnings: 
2021-05-10T04:22:37.745+0000 I STORAGE  [initandlisten] 
2021-05-10T04:22:37.745+0000 I STORAGE  [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2021-05-10T04:22:37.745+0000 I STORAGE  [initandlisten] **          See http://dochub.mongodb.org/core/prodnotes-filesystem
2021-05-10T04:22:38.719+0000 I CONTROL  [initandlisten] 
2021-05-10T04:22:38.719+0000 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2021-05-10T04:22:38.719+0000 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2021-05-10T04:22:38.719+0000 I CONTROL  [initandlisten] 
> exit
bye

new_password=123
echo $new_password

echo "
use admin
db.changeUserPassword('root', '$new_password')
exit
" | mongo

new_password=$(pwgen -ncCs 15 1)
echo $new_password

echo "
use admin
db.changeUserPassword('root', '$new_password')
exit
" | mongo