I noticed a lot of these answers, use this command:
use admin
which switches to the admin database. At least in Mongo v4.0.6, creating a user in the context of the admin database will create a user with "_id" : "admin.administrator":
> use admin
> db.getUsers()
[ ]
> db.createUser({ user: 'administrator', pwd: 'changeme', roles: [ { role: 'root', db: 'admin' } ] })
> db.getUsers()
[
{
"_id" : "admin.administrator",
"user" : "administrator",
"db" : "admin",
"roles" : [
{
"role" : "root",
"db" : "admin"
}
],
"mechanisms" : [
"SCRAM-SHA-1",
"SCRAM-SHA-256"
]
}
]
I emphasize "admin.administrator", for I have a Mongoid (mongodb ruby adapter) application with a different database than admin and I use the URI to reference the database in my mongoid.yml configuration:
development:
clients:
default:
uri: <%= ENV['MONGODB_URI'] %>
options:
connect_timeout: 15
retry_writes: false
This references the following environment variable:
export MONGODB_URI='mongodb://administrator:[email protected]/mysite_development?retryWrites=true&w=majority'
Notice the database is mysite_development, not admin. When I try to run the application, I get an error "User administrator (mechanism: scram256) is not authorized to access mysite_development".
So I return to the Mongo shell delete the user, switch to the specified database and recreate the user:
$ mongo
> db.dropUser('administrator')
> db.getUsers()
[]
> use mysite_development
> db.createUser({ user: 'administrator', pwd: 'changeme', roles: [ { role: 'root', db: 'admin' } ] })
> db.getUsers()
[
{
"_id" : "mysite_development.administrator",
"user" : "administrator",
"db" : "mysite_development",
"roles" : [
{
"role" : "root",
"db" : "admin"
}
],
"mechanisms" : [
"SCRAM-SHA-1",
"SCRAM-SHA-256"
]
}
]
Notice that the _id and db changed to reference the specific database my application depends on:
"_id" : "mysite_development.administrator",
"db" : "mysite_development",
After making this change, the error went away and I was able to connect to MongoDB fine inside my application.
Extra Notes:
In my example above, I deleted the user and recreated the user in the right database context. Had you already created the user in the right database context but given it the wrong roles, you could assign a mongodb built-in role to the user:
db.grantRolesToUser('administrator', [{ role: 'root', db: 'admin' }])
There is also a db.updateUser command, albiet typically used to update the user password.