Charmed MySQL K8s Tutorial > 5. Integrate with other applications
Integrate with other applications
Integrations, known as “relations” in Juju 2.9, are the easiest way to create a user for a Charmed MySQL application.
Integrations automatically create a username, password, and database for the desired user/application. As mentioned in the earlier section about accessing MySQL, it is better practice to connect to MySQL via a specific user instead of the root user.
In this section, you will learn how to integrate your Charmed MySQL with another application (charmed or not) via the Data Integrator charm.
Summary
Deploy data-integrator
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. It automatically provides credentials and endpoints that are needed to connect with a charmed database application.
In order to deploy the Data Integrator charm we can use the command juju deploy we have learned above:
To deploy data-integrator, run
juju deploy data-integrator --config database-name=test-database
Example output:
Located charm "data-integrator" in charm-hub, revision 13
Deploying "data-integrator" from charm-hub charm "data-integrator", revision 3 in channel edge on jammy
Running juju status will show you data-integrator in a blocked state. This state is expected due to not-yet established relation (integration) between applications.
Model Controller Cloud/Region Version SLA Timestamp
tutorial overlord microk8s/localhost 3.5.2 unsupported 22:54:31+01:00
App Version Status Scale Charm Channel Rev Address Exposed Message
data-integrator waiting 1 data-integrator edge 4 10.152.183.180 no installing agent
mysql-k8s 8.0.31 active 2 mysql-k8s 8.0/stable 36 10.152.183.234 no
Unit Workload Agent Address Ports Message
data-integrator/0* blocked idle 10.1.84.66 Please relate the data-integrator with the desired product
mysql-k8s/0* active idle 10.1.84.74 Unit is ready: Mode: RW
mysql-k8s/1 active idle 10.1.84.127 Unit is ready: Mode: RO
The blocked state is expected due to not-yet established relation (integration) between applications.
Integrate with MySQL
Now that the data-integrator charm has been set up, we can relate it to MySQL. This will automatically create a username, password, and database for data-integrator.
Relate the two applications with:
juju relate data-integrator mysql-k8s
Wait for juju status --watch 1s to show all applications/units as active:
Model Controller Cloud/Region Version SLA Timestamp
tutorial overlord microk8s/localhost 3.5.2 unsupported 22:55:44+01:00
App Version Status Scale Charm Channel Rev Address Exposed Message
data-integrator waiting 1 data-integrator edge 4 10.152.183.180 no installing agent
mysql-k8s 8.0.31 active 2 mysql-k8s 8.0/stable 36 10.152.183.234 no
Unit Workload Agent Address Ports Message
data-integrator/0* active idle 10.1.84.66
mysql-k8s/0* active idle 10.1.84.74 Unit is ready: Mode: RW
mysql-k8s/1 active idle 10.1.84.127 Unit is ready: Mode: RO
To retrieve the username, password and database name, run the command
juju run data-integrator/leader get-credentials
Example output:
unit-data-integrator-0:
UnitId: data-integrator/0
id: "20"
results:
mysql:
endpoints: mysql-k8s-0.mysql-k8s-endpoints:3306
password: 7VRfmGjfUI1pVUPsfbMwmHFm
read-only-endpoints: mysql-k8s-0.mysql-k8s-endpoints:3306,mysql-k8s-1.mysql-k8s-endpoints:3306
username: relation-3
version: 8.0.31-0ubuntu0.22.04.1
ok: "True"
status: completed
timing:
completed: 2023-02-15 21:56:22 +0000 UTC
enqueued: 2023-02-15 21:56:17 +0000 UTC
started: 2023-02-15 21:56:21 +0000 UTC
Note that your hostnames, usernames, and passwords will be different.
Access the integrated database
Use endpoints, username, password from above to connect newly created database test-database on MySQL server:
> mysql -h 10.1.84.74 -u relation-3 -p7VRfmGjfUI1pVUPsfbMwmHFm -e "show databases;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
The newly created database test-database is also available on all other MySQL K8s cluster members:
> mysql -h 10.1.84.127 -u relation-3 -p7VRfmGjfUI1pVUPsfbMwmHFm -e "show databases;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
When you integratetwo applications, Charmed MySQL K8s automatically sets up a new user and database for you. Note the database name we specified when we first deployed the data-integrator charm: --config database-name=test-database.
Remove the user
To remove the user, remove the integration. Removing the integration automatically removes the user that was created when the integration was created.
To remove the integration, run the following command:
juju remove-relation mysql-k8s data-integrator
Try to connect to the same MySQL you just used in the previous section (Access the related database):
mysql -h 10.1.84.74 -u relation-3 -p7VRfmGjfUI1pVUPsfbMwmHFm -e "show databases;"
This will output an error message, since the user no longer exists.
ERROR 1045 (28000): Access denied for user 'relation-3'@'10.76.203.127' (using password: YES)
This is expected, as juju remove-relation mysql-k8s data-integrator also removes the user.
Note: Data remains on the server at this stage.
To create a user again, re-integrate the applications:
juju integrate data-integrator mysql-k8s
Re-integrating generates a new user and password. Obtain these credentials as before, with the get-credentials action:
juju run data-integrator/leader get-credentials
You can connect to the database with this new credentials. From here you will see all of your data is still present in the database.
Next step: 6. Enable TLS encryption