Update role user: not authorized on admin to execute command

Question

When I try to get info about replica I get the following error:

rep0:PRIMARY> rs.printReplicationInfo()
2015-05-19T13:30:29.231+0200 error: {
        "$err" : "not authorized for query on local.system.namespaces",
        "code" : 13
} at src/mongo/shell/query.js:131

I have tried to execute the command with the two following users:

    [
        {
                "_id" : "admin.siteRootAdmin",
                "user" : "siteRootAdmin",
                "db" : "admin",
                "roles" : [
                        {
                                "role" : "root",
                                "db" : "admin"
                        }
                ]
        },
        {
                "_id" : "admin.mongoadmin",
                "user" : "mongoadmin",
                "db" : "admin",
                "roles" : [
                        {
                                "role" : "userAdminAnyDatabase",
                                "db" : "admin"
                        },
                        {
                                "role" : "dbOwner",
                                "db" : "admin"
                        },
                        {
                                "role" : "clusterAdmin",
                                "db" : "admin"
                        }
                ]
        }
]

Althought I have clusterAdmin role to work with replicas, I have tried to update roles of mongoadmin to read local database (as all roles are granted on admin db) but I get the following error:

rep0:PRIMARY> db.system.users.update({"user":"mongoadmin"},{$addToSet:{"roles":"readAnyDatabase"}})
WriteResult({
        "writeError" : {
                "code" : 13,
                "errmsg" : "not authorized on admin to execute command { update: \"system.users\", updates: [ { q: { user: \"mongoadmin\" }, u: { $addToSet: { roles: \"readAnyDatabase\" } }, multi: false, upsert: false } ], ordered: true }"
        }
})

• What is supposed I need to have in order to get full access to all replica commands in addition to clusterAdmin role?
• If any of both users have permissions in admin db (mongoadmin is dbOwner), why I don't have permissions for update command?

Answer 1

I was updating roles with the wrong command here is the right one:

db.grantRolesToUser( "mongoadmin", [{ role: "read", db: "local"}])

Now I can check the replicainfo:

rep0:PRIMARY> rs.printReplicationInfo()
configured oplog size:   990MB
log length start to end: 617347secs (171.49hrs)
oplog first event time:  Thu May 14 2015 14:25:04 GMT+0200 (CEST)
oplog last event time:   Thu May 21 2015 17:54:11 GMT+0200 (CEST)
now:                     Thu May 21 2015 17:54:24 GMT+0200 (CEST)