Monitoring replication_lag with authorization gives a generic error

[mvdwalle]

I am monitoring my mongodb replicaset with this plugin and encountered the following error:
CRITICAL - General MongoDB Error: can't set attribute

I am running the command as follows:
/usr/lib/nagios/plugins/check_mongodb -A replication_lag -W 5 -C 10 -M 3 -u {user} --pass={pass}

I have tested the plugin on a set without authentication and everything works fine.

[mvdwalle]

I managed to trace this down to def set_read_preference(db) it tries to set the read preference however this: http://api.mongodb.org/python/current/api/pymongo/database.html#pymongo.database.Database.read_preference

states that the property is now read only.

[hdeheer]

@mvdwalle which version of PyMongo are you using?
I'm interested to see if my pull request (#161) will fix your issue if you're using PyMongo > 3.x
See also: hdeheer@65a9af1

[mvdwalle]

I am using version 3.0.3, your pull request unfortunatly does not solve the problem. In pymongo 3+ the read preference cannot be changed on the connection level any more and needs to be sent with the command:

set_read_preference(con.admin) cannot be used anymore.

[hdeheer]

Ok, I will have a look. Maybe can drop the whole function as setting read_preference/slave_okay is already done in mongo_connect()

[BoemmLA]

That would be great, I hit the same problem and thought I used the wrong python version or so ...
But if it can be fixed in the monitoring script it would be great!

[mvdwalle]

Setting read preference might be needed for some checks. But you can do it on query time. I did that for this specific check:

rs_status = con.admin.command("replSetGetStatus", read_preference=pymongo.ReadPreference.SECONDARY)

[err0rs]

for the time being i am downgrading to "pip install pymongo==2.8"

[warrenpnz]

Your problem is that the read prefernce function is trying to set a read only variable. Change it to this:

def set_read_preference(db):
    if pymongo.version >= "2.2":
        pymongo.read_preferences.Secondary
    else:
        db.read_preference = pymongo.ReadPreference.SECONDARY