mongo-admin

Basic Cluster Administration

mongod is the core database process. mongo is the interactive MongoDB shell that you use to connect to mongod.

mongod shell command

mongod --dbpath /data/db --logpath /data/log/mongod.log --fork --replSet "M103" --keyFile /data/keyfile --bind_ip "127.0.0.1,192.168.103.100" --tlsMode requireTLS --tlsCAFile "/etc/tls/TLSCA.pem" --tlsCertificateKeyFile "/etc/tls/tls.pem"

note : --bind_ip 127.0.0.1,192.168.103.100

Equivalent mongod.conf

storage:
  dbPath: /data/db/
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: first_mongod/mongod.log

# network interfaces
net:
  port: 27000
  bindIp: "127.0.0.1,192.168.103.100"


# how the process runs
processManagement:
   fork: true
   timeZoneInfo: /usr/share/zoneinfo
tls:
  mode: "requireTLS"
  certificateKeyFile: "/etc/tls/tls.pem"
  CAFile: "/etc/tls/TLSCA.pem"
security:
  keyFile: "/data/keyfile"
processManagement:
  fork: true
security:
  authorization: enabled

Create admin user

mongo admin --host localhost:27000 --eval '
  db.createUser({
    user: "m103-admin",
    pwd: "m103-pass",
    roles: [
      {role: "root", db: "admin"}
    ]
  })
'

Create application user

db.createUser(
  { user: "m103-application-user",
    pwd: "m103-application-pass",
    roles: [ { db: "applicationData", role: "readWrite" } ]
  }
)

Assign conf file to mongod

mongod --config /etc/mongod.conf

Common issue faced while using conf

1. ERROR: child process failed, exited with error number 1 To see additional information in this output, start without the "--fork" option

vagrant@m103:~$ sudo nano /etc/mongod.conf
vagrant@m103:~$ mongod --config /etc/mongod.conf

2020-03-09T12:28:25.617+0000 F CONTROL [main] Failed global initialization: FileNotOpen: Failed to open "/first_mongod/mongod.log"

Solution: Make sure the folder is created, else create it using mkdir and assign RW access

sudo chown vagrant:vagrant first_mongod/mongod.log

2020-03-09T12:40:31.616+0000 E QUERY [thread1] Error: listDatabases failed:{ "ok" : 0, "errmsg" : "there are no users authenticated", "code" : 13, "codeName" : "Unauthorized" } : _getErrorWithCode@src/mongo/shell/utils.js:25:13 Mongo.prototype.getDBs@src/mongo/shell/mongo.js:67:1 shellHelper.show@src/mongo/shell/utils.js:860:19 shellHelper@src/mongo/shell/utils.js:750:15 @(shellhelp2):1:1 MongoDB Enterprise > db.auth('m103-admin','m103-pass') Error: Authentication failed.

Solution: Login with user credentials

mongo --host localhost:27000  --authenticationDatabase "admin" -u "m103-admin" -p "m103-pass"

3. QUERY [thread1] Error: listDatabases failed:{ "ok" : 0, "errmsg" : "not master and slaveOk=false", "code" : 13435, "codeName" : "NotMasterNoSlaveOk" } : _getErrorWithCode@src/mongo/shell/utils.js:25:13 Mongo.prototype.getDBs@src/mongo/shell/mongo.js:67:1 shellHelper.show@src/mongo/shell/utils.js:860:19 shellHelper@src/mongo/shell/utils.js:750:15 @(shellhelp2):1:1

Solution: Note: rs is the replication set

MongoDB Enterprise >

rs.status() 
{
	"info" : "run rs.initiate(...) if not yet done for the set",
	"ok" : 0,
	"errmsg" : "no replset config has been received",
	"code" : 94,
	"codeName" : "NotYetInitialized"
}

MongoDB Enterprise >

rs.initiate() 
{
	"info2" : "no configuration specified. Using a default configuration for the set",
	"me" : "192.168.103.100:27000",
	"ok" : 1
}

MongoDB Enterprise M103:OTHER>

rs.status()
{
	"set" : "M103",
	"date" : ISODate("2020-03-09T12:49:58.116Z"),
	"myState" : 1,
	"term" : NumberLong(1),
	"syncingTo" : "",
	"syncSourceHost" : "",
	"syncSourceId" : -1,
	"heartbeatIntervalMillis" : NumberLong(2000),
 ( Not complete)

4. Different DB path than the default path /data/db. Mongod will now store data files in this new directory instead. Solution: create a new folder /var/mongodb/db/ and allow mongod to write files to this directory create this directory with sudo, because /var is owned by root use chown to change the owner of this directory to vagrant:vagrant edit your config file to use this new directory as the dbpath

use admin
db.shutdownServer()
quit()

Start to see reflected changes

~$ mongod --config /etc/mongod.conf
Aborted (core dumped)

Solution: Likely there is an other instance of mongod running. Find the process and kill it

To find process

vagrant@m103:~$ sudo lsof -i -P -n | grep 27000 
mongod    2109 vagrant   12u  IPv4  13601      0t0  TCP 127.0.0.1:27000 (LISTEN)
mongod    2109 vagrant   13u  IPv4  13602      0t0  TCP 192.168.103.100:27000 (LISTEN)
mongo     2138 vagrant    4u  IPv4  13619      0t0  TCP 127.0.0.1:56336->127.0.0.1:27000 (ESTABLISHED)


vagrant@m103:~$ sudo lsof -i -P -n | grep mongod
mongod    2109 vagrant   12u  IPv4  13601      0t0  TCP 127.0.0.1:27000 (LISTEN)
mongod    2109 vagrant   13u  IPv4  13602      0t0  TCP 192.168.103.100:27000 (LISTEN)

To kill the process kill -9 2109

6. Detected unclean shutdown - /data/db/mongod.lock is not empty.

Solution:

mongod --repair

Not recommanded but if you want to repair your data files without preserving the original files

sudo rm /var/lib/mongodb/mongod.lock
sudo mongod --dbpath /var/lib/mongodb/ --repair
sudo mongod --dbpath /var/lib/mongodb/ --journal

Make sure that you leave you terminal running in which you have run above lines, don't press 'Ctrl+c' or quit it. Type the command to start mongo now in another window.

7. Error: couldn't connect to server localhost:27000, connection attempt failed: SocketException: Error connecting to localhost:27000 (127.0.0.1:27000) :: caused by :: Connection refused : connect@src/mongo/shell/mongo.js:343:13 @(connect):2:6 exception: connect failed

Hint: Check the mongod logs for failure

8. exception in initAndListen: 29 Data directory /data/db not found., terminating Solution: Error happen because dbpath /data/db/ (default config) does not exist. You need to create data folder and set permission for it.

sudo mkdir -p /data/db/ 
sudo chown id -u /data/db

then start the mongo