Relate your MongoDB deployment
This is part of the Charmed MongoDB Tutorial. Please refer to this page for more information and the overview of the content.
Relations
Relations, or what Juju documentation describes as Integration, are the easiest way to create a user for MongoDB in Charmed MongoDB. Relations automatically create a username, password, and database for the desired user/application. As mentioned earlier in the Access MongoDB section it is a better practice to connect to MongoDB via a specific user rather than the admin user.
Data Integrator Charm
Before relating to a charmed application, we must first deploy our charmed application. In this tutorial we will relate to the Data Integrator Charm. This is a bare-bones charm that allows for central management of database users, providing support for different kinds of data platforms (e.g. MongoDB, MySQL, PostgreSQL, Kafka, etc) with a consistent, opinionated and robust user experience. In order to deploy the Data Integrator Charm we can use the command juju deploy we have learned above:
juju deploy data-integrator --channel edge --config database-name=test-database
The expected output:
Located charm "data-integrator" in charm-hub...
Deploying "data-integrator" from charm-hub charm "data-integrator"...
Relate to MongoDB
Now that the Database Integrator Charm has been set up, we can relate it to MongoDB. This will automatically create a username, password, and database for the Database Integrator Charm. Relate the two applications with:
juju integrate data-integrator mongodb
Wait for watch -n 1 -c juju status to show:
ubuntu@ip-172-31-11-104:~/data-integrator$ juju status
Model Controller Cloud/Region Version SLA Timestamp
tutorial overlord localhost/localhost 3.1.6 unsupported 10:32:09Z
App Version Status Scale Charm Channel Rev Exposed Message
data-integrator active 1 data-integrator edge 3 no
mongodb active 2 mongodb 6/beta 140 no
Unit Workload Agent Machine Public address Ports Message
data-integrator/0* active idle 5 10.23.62.216 received mongodb credentials
mongodb/0* active idle 0 10.23.62.156 27017/tcp
mongodb/1 active idle 1 10.23.62.55 27017/tcp Replica set primary
Machine State Address Inst id Series AZ Message
0 started 10.23.62.156 juju-d35d30-0 jammy Running
1 started 10.23.62.55 juju-d35d30-1 jammy Running
5 started 10.23.62.216 juju-d35d30-5 jammy Running
To retrieve information such as the username, password, and database. Enter:
juju run data-integrator/leader get-credentials
This should output something like:
Running operation 21 with 1 task
- task 22 on unit-data-integrator-0
Waiting for task 22...
mongodb:
database: test-database
endpoints: 10.63.102.106,10.63.102.223
password: kXOOyTbccn2cXs3kokOqPJz3Mu9g3a5g
replset: mongodb
uris: mongodb://relation-2:kXOOyTbccn2cXs3kokOqPJz3Mu9g3a5g@10.63.102.106,10.63.102.223/test-database?replicaSet=mongodb&authSource=admin
username: relation-2
ok: "True"
Save the value listed under uris: (Note: your hostnames, usernames, and passwords will likely be different.)
Access the related database
Notice that in the previous step when you typed juju run data-integrator/leader get-credentials the command not only outputted the username, password, and database, but also outputted the URI.
This means you do not have to generate the URI yourself. To connect to this URI first ssh into mongodb/0:
juju ssh mongodb/0
Then access mongo with the URI that you copied above:
charmed-mongodb.mongosh "<uri copied from juju run data-integrator/leader get-credentials>"
Note: be sure you wrap the URI in " with no trailing whitespace.
You will now be in the mongo shell as the user created for this relation. When you relate two applications Charmed MongoDB automatically sets up a user and database for you. Enter db.getName() into the MongoDB shell, this will output:
test-database
This is the name of the database we specified when we first deployed the data-integrator charm. To create a collection in the “test-database” and then show the collection enter:
db.createCollection("test-collection")
show collections
Now insert a document into this database:
db.test_collection.insertOne(
{
First_Name: "Jammy",
Last_Name: "Jellyfish",
})
You can verify this document was inserted by running:
db.test_collection.find()
Now exit the MongoDB shell by typing:
exit
Now you should be back in the host of Charmed MongoDB (mongodb/0). To exit this host type:
exit
You should now be shell you started in where you can interact with Juju and LXD.
Remove the user
To remove the user, remove the relation. Removing the relation automatically removes the user that was created when the relation was created. Enter the following to remove the relation:
juju remove-relation mongodb data-integrator
Now try again to connect to the same URI you just used in Access the related database:
juju ssh mongodb/0
charmed-mongodb.mongosh "<uri copied from juju run-action data-integrator/leader get-credentials --wait>"
Note: be sure you wrap the URI in " with no trailing whitespace.
This will output an error message:
Current Mongosh Log ID: 638f5ffbdbd9ec94c2e58456
Connecting to: mongodb://<credentials>@10.23.62.38,10.23.62.219/mongodb?replicaSet=mongodb&authSource=admin&appName=mongosh+1.6.1
MongoServerError: Authentication failed.
As this user no longer exists. This is expected as juju remove-relation mongodb data-integrator also removes the user.
Now exit the juju:
exit
You should now be shell you started in where you can interact with Juju and LXD.
If you wanted to recreate this user all you would need to do is relate the the two applications again:
juju integrate data-integrator mongodb
Re-relating generates a new password for this user, and therefore a new URI you can see the new URI with:
juju run data-integrator/leader get-credentials
Save the result listed with uris:.
You can connect to the database with this new URI:
juju ssh mongodb/0
charmed-mongodb.mongosh "<uri copied from juju run data-integrator/leader get-credentials>"
Note: be sure you wrap the URI in " with no trailing whitespace.
From there if you enter db.test_collection.find() you will see all of your original documents are still present in the database.
Now exit the MongoDB shell by typing:
exit
Now you should be back in the host of Charmed MongoDB (mongodb/0). To exit this host type:
exit
You should now be shell you started in where you can interact with Juju and LXD.