1. 1.run install.sh file in all 3 servers.
2.  
3. 2.vim /etc/mongod.conf (in all 3 servers.)
4.  
5.         net:
6.                 bindIp: 0.0.0.0
7.                
8.         replication:
9.            replSetName: "my_rep"
10.            
11.         #save file
12.  
13. 3. get mongo shell -> mongo (only in one server)
14.  
15.         run below command only in one server. *** CHANGE DNS BEFORE RUN THIS.
16.  
17.         rs.initiate({_id : "my_rep",members: [{ _id: 0, host: "mongo1.facetone.lk:27017" },{ _id: 1, host: "mongo2.facetone.lk:27017" },{ _id: 2, host: "mongo3.facetone.lk:27017" }]})
18.  
19. 4. check replication
20.         rs.status()
21.         rs.conf()
22.        
23. 5. Convert one secondary as an arbiter
24.         stop service in the needed server
25.         remove from replica-set (in primary)
26.                 rs.remove("sec_ip:port")
27.         remove data from data dir
28.         create dir again & set permissions
29.         start service
30.         in primary
31.                 rs.addArb("ser_ip:port")
32.         check rs.status()
33.        
34. 6. add user
35.  
36.         db.createUser({user:"duo", pwd:"DuoS123", roles:[{role:"root", db:"admin"}]})
37.  
38. ##################################################################################
39. #install.sh file
40. apt-get update
41. wget -qO - https://www.mongodb.org/static/pgp/server-4.0.asc | sudo apt-key add -
42.  
43. echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu bionic/mongodb-org/4.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.0.list
44.  
45. apt-get update
46.  
47. sudo apt-get install -y mongodb-org=4.0.19 mongodb-org-server=4.0.19 mongodb-org-shell=4.0.19 mongodb-org-mongos=4.0.19 mongodb-org-tools=4.0.19
48.  
49. #stop updating mongod
50. echo "mongodb-org hold" | sudo dpkg --set-selections
51. echo "mongodb-org-server hold" | sudo dpkg --set-selections
52. echo "mongodb-org-shell hold" | sudo dpkg --set-selections
53. echo "mongodb-org-mongos hold" | sudo dpkg --set-selections
54. echo "mongodb-org-tools hold" | sudo dpkg --set-selections
55.  
56. systemctl start mongod
57.  
58. systemctl enable mongod
59.  
60. echo "Mongo 4.0.19 installed"
61.  
62. mongod -version
63.  
64. #end
65.  
66. #######
67. LINKS
68. https://docs.mongodb.com/v4.0/installation/
69.        
70.        
71.        
72.        
73.        
74.        
75.