No logs in mongo v4.4

Ops and Admin
1

For mongodb@4.4 community edition, I don’t see any logs being written.

  • Yes, I have the correct config in /etc/mongodb.conf
systemLog:
    destination: file
    path: /var/log/mongodb/mongod.log
    logAppend: true
  • Yes, I have the correct permission for /var/log/mongodb/mongod.log and its parent folders (mongodb:mongodb)
  • I have set the profiling level to log all queries `db.setProfilingLevel(2, -1)

But the file size of /var/log/mongodb/mongod.log is 0

2

Most likely the mongod instance is not using the configuration file you shared.

How did you started mongod?

How do you connect to mongod?

Share the output of the following commands:

ss -tlnp
ps -aef | grep [m]ongo
3

Running mongo server using systemctl on ubuntu@18.
Can confirm that it is using the right config file /etc/mongod.conf
I connect to mongo using mongodb nodejs package mongodb@4.6.0

$ ps -aef | grep [m]ongo
mongodb  14400     1 99 Jun29 ?        295-20:17:30 /usr/bin/mongod --config /etc/mongod.conf

$ ss -tlnp
State  Recv-Q  Send-Q      Local Address:Port      Peer Address:Port                                     
LISTEN 0       128             127.0.0.1:6379           0.0.0.0:*                                        
LISTEN 0       128               0.0.0.0:80             0.0.0.0:*                                        
LISTEN 0       128         127.0.0.53%lo:53             0.0.0.0:*                                        
LISTEN 0       128               0.0.0.0:22             0.0.0.0:*                                        
LISTEN 0       128               0.0.0.0:443            0.0.0.0:*                                        
LISTEN 0       128             127.0.0.1:27017          0.0.0.0:*                                        
LISTEN 0       128                     *:8080                 *:*      users:(("node",pid=11366,fd=10))  
LISTEN 0       128                  [::]:22                [::]:*                                        
LISTEN 0       128                     *:3000                 *:*      users:(("node /home/prad",pid=17598,fd=19))

Contents of /etc/mongod.conf

storage:
  dbPath: /var/lib/mongodb
  journal:
    enabled: true

systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

net:
  port: 27017
  bindIp: 127.0.0.1

processManagement:
  timeZoneInfo: /usr/share/zoneinfo

security:
  authorization: "enabled"
4

Output of the command:

ls -al /var/log/mongodb/mongod.log
5 
-rw------- 1 mongodb mongodb 0 Jul 10 06:25 /var/log/mongodb/mongod.log
6

B-(

The above is the face of a perplex person.

I will come back later, hopefully with B-)

1 Like
7

Output of the command

df -v /var/log/mongodb/
8

The machine has a lot of space as well as memory available

9

I see a few possibilities.

The configuration file has changed since mongod was started and the running instance is in fact writing into a different file. In mongosh you might try

db.adminCommand( { getLog: "global" } )

to see if you can find log entries for initandlisten.

Commands such as

/bin/rm /var/log/mongodb/mongod.log
/bin/cp /dev/null /var/log/mongodb/mongod.log

were issued replacing the file that mongod is writing into. But mongod is still writing in the original file handle of the file. Some people do that when they do not run logRotate and the file becomes too big with the false hope that the original file is truncated.

1 Like
10

thank you. you are right. With the first command, I checked the logs were coming in fact.
Restarting the mongodb server fixed the issue. now I can see the logs in mongod.log.

And probably logrotate might be the culprit here. Is there anything wrong with my logrotate config that could have caused this issue?

/var/log/mongodb/mongod*.log {
        weekly
        dateext
        missingok
        rotate 12
        compress
        notifempty
}
1 Like
11

I do not know enough about logrotate utility but you could look at

and

and

Of particular attention is the sentence:

reopen closes and reopens the log file following the typical Linux/Unix log rotate behavior. Use reopen when using the Linux/Unix logrotate utility to avoid log loss.

The default value is rename which seems to be incompatible with logrotate utility.

12

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