I haven't downloaded the log file. I've inspected it using cat and tail, and it's the same repeating pattern I provided earlier from the redacted log file.

I came across this Wekan issue, not sure if it's related?
Wekan's mongodb.log grows pretty large (unlimited?)

Did you ever download the whole log file and inspect it?
Maybe there is something even visually repeating that might indicate something.

If you have the option, maybe upload the big log file or the last 500MB of that log file somewhere so I can also take a look at a bigger chunk.

Hello @alex-a-soto
Please share an excerpt of that log file.
Maybe I can see something.

Hi @james, I've shared an excerpt of the log file, redacted some parts.

2025-06-12T10:49:13-04:00 {"t":{"$date":"2025-06-12T14:49:13.303+00:00"},"s":"I","c":"COMMAND","id":[REDACTED_ID],"ctx":"[REDACTED_CTX]","msg":"Slow query","attr":{"type":"command","ns":"[REDACTED_DB].[REDACTED_COLLECTION]","command":{"find":"[REDACTED_COLLECTION]","filter":{"cardId":{"$in":[ /* …redacted list of IDs… */ ]}}},"lsid":{"id":{"$uuid":"[REDACTED_UUID]"}},"$clusterTime":{"clusterTime":{"$timestamp":{"t":[REDACTED_TS_T],"i":1}},"signature":{"hash":"[REDACTED_SIG_HASH]","keyId":[REDACTED_KEY_ID]}}},"$db":"[REDACTED_DB]","planSummary":"COLLSCAN","planningTimeMicros":89,"keysExamined":0,"docsExamined":0,"nBatches":1,"cursorExhausted":true,"numYields":0,"nreturned":0,"queryHash":"[REDACTED_QUERY_HASH]","planCacheKey":"[REDACTED_PLAN_CACHE_KEY]","queryFramework":"classic","reslen":253,"locks":{ /* …intact… */ },"readConcern":{"level":"local"},"storage":{},"cpuNanos":139903,"remote":"[REDACTED_IP]:[REDACTED_PORT]","protocol":"op_msg","durationMillis":0}  

2025-06-12T10:49:21-04:00 {"t":{"$date":"2025-06-12T14:49:21.853+00:00"},"s":"D1","c":"STORAGE","id":[REDACTED_ID],"ctx":"TimestampMonitor","msg":"No drop-pending idents have expired","attr":{"timestamp":{"$timestamp":{"t":[REDACTED_TS_T],"i":1}},"pendingIdentsCount":0}}  

2025-06-12T10:49:23-04:00 {"t":{"$date":"2025-06-12T14:49:23.311+00:00"},"s":"D1","c":"REPL","id":[REDACTED_ID],"ctx":"[REDACTED_CONN]","msg":"Waiting for a hello response from a topology change or until deadline","attr":{"deadline":{"$date":"2025-06-12T14:49:33.311Z"},"currentTopologyVersionCounter":6}}  

2025-06-12T10:49:25-04:00 {"t":{"$date":"2025-06-12T14:49:25.463+00:00"},"s":"D1","c":"REPL","id":[REDACTED_ID],"ctx":"NoopWriter","msg":"Set last known op time","attr":{"lastKnownOpTime":{"ts":{"$timestamp":{"t":[REDACTED_TS_T],"i":1}},"t":[REDACTED_TERM]}}}  

As of now, to size are:

6.4G    ./app.log
6.0G    ./app.log.1

Hello @alex-a-soto

It might be a good idea to clear the MongoDB logs, disable wekan to confirm if this is the issue.

Hi @james, I cleared the MongoDB logs, disabled Wekan, waited for about 10 minutes, and checked app.log and app.log.1, the file size stayed the same during that time.

I restarted Wekan and noticed that both log files began increasing in size again by about 1.0 MB in minutes.

The logs show repeated hello commands from Wekan to MongoDB that time out or wait for responses.

2025-06-10T19:04:51.245+00:00 - "Error while waiting for hello response"
2025-06-10T19:04:51.245+00:00 - "Slow query"
2025-06-10T19:04:51.245+00:00 - "Waiting for a hello response from a topology change or until deadline"

It might be a good idea to clear the MongoDB logs, disable wekan to confirm if this is the issue.

There is/was this issue https://forum.cloudron.io/topic/13361/after-ubuntu-22-24-upgrade-syslog-getting-spammed-and-grows-way-to-much-clogging-up-the-diskspace might be also the case here.

Needs to be validated.

I'll check to see if it's related to the Ubuntu upgrade.

I ran head -n 1 app.log and got a MongoDB log entry noting a find query by _id, labeled as a "slow query" even though it completed instantly (0ms).

What apps are you using?

n8n, Cal.com Nextcloud, Baserow, HedgeDoc, SOGo, Wekan

I started noticing this after installing Wekan.

@alex-a-soto said in Unexpected Large Log Files in /home/yellowtent/platformdata/logs/mongodb:

Is there a known issue or misconfiguration that could cause these files to grow to this size?

No.
There is/was this issue https://forum.cloudron.io/topic/13361/after-ubuntu-22-24-upgrade-syslog-getting-spammed-and-grows-way-to-much-clogging-up-the-diskspace might be also the case here.
Needs to be validated.

@alex-a-soto said in Unexpected Large Log Files in /home/yellowtent/platformdata/logs/mongodb:

If these are app-specific logs, what controls their retention and rotation?

Since this is about the /home/yellowtent/platformdata/logs/mongodb log file, it could be that one of your apps that uses MongoDB is running an absurd amount of querys.
What apps are you using?