How to access MySQL Router outside of Kubernetes¶
To expose a Charmed MySQL K8s database externally, this charm (MySQL Router K8s) should be deployed and related with the Charmed MySQL K8s application. Charmed MySQL Router K8s then provides a configuration option expose-external (with options false, nodeport and loadbalancer) to control precisely how the database will be externally exposed.
By default (when expose-external=false), Charmed MySQL Router K8s creates a K8s service of type ClusterIP which it provides as endpoints to the related client applications. These endpoints are only accessible from within the K8s namespace (or juju model) where the MySQL Router K8s application is deployed.
Below is a juju model where MySQL Router K8s is related to MySQL K8s and Data Integrator, which we will later use to demonstrate the configuration of expose-external:
$ juju status --relations
Model Controller Cloud/Region Version SLA Timestamp
database uk8s-3-6-1 microk8s/localhost 3.6.19 unsupported 14:39:08Z
App Version Status Scale Charm Channel Rev Address Exposed Message
data-integrator active 1 data-integrator latest/stable 78 10.152.183.44 no
mysql-k8s 8.4.10 active 1 mysql-k8s 8.4/stable 10.152.183.143 no
mysql-router-k8s 8.4.10 active 1 mysql-router-k8s 8.4/stable 10.152.183.201 no
Unit Workload Agent Address Ports Message
data-integrator/0* active idle 10.1.241.219
mysql-k8s/0* active idle 10.1.241.217 Primary
mysql-router-k8s/0* active idle 10.1.241.218
Integration provider Requirer Interface Type Message
data-integrator:data-integrator-peers data-integrator:data-integrator-peers data-integrator-peers peer
mysql-k8s:database mysql-router-k8s:backend-database mysql_client regular
mysql-k8s:database-peers mysql-k8s:database-peers mysql_peers peer
mysql-k8s:rolling-ops mysql-k8s:rolling-ops rolling_op peer
mysql-k8s:refresh-v-three mysql-k8s:refresh-v-three refresh peer
mysql-router-k8s:cos mysql-router-k8s:cos cos peer
mysql-router-k8s:database data-integrator:mysql mysql_client regular
mysql-router-k8s:mysql-router-peers mysql-router-k8s:mysql-router-peers mysql_router_peers peer
mysql-router-k8s:refresh-v-three mysql-router-k8s:refresh-v-three refresh peer
When expose-external=false, the following shows the endpoints returned to the client:
$ juju run data-integrator/0 get-credentials
mysql:
data: '{"database": "test-database", "external-node-connectivity": "true", "requested-secrets":
"[\"username\", \"password\", \"tls\", \"tls-ca\", \"uris\"]"}'
database: test-database
endpoints: mysql-router-k8s-service.database.svc.cluster.local:6446
password: VRLNoVx6Br4Vn5SNHdoMK52Q
read-only-endpoints: mysql-router-k8s-service.database.svc.cluster.local:6447
username: relation-7_4fc92c2813524d6-8
ok: "True"
The following shows a MySQL client connecting to the provided endpoints from the data integrator unit (which is deployed in the same K8s namespace, i.e. the same juju model, as MySQL Router K8s):
$ juju ssh data-integrator/0 bash
root@data-integrator-0:/var/lib/juju# mysql -h mysql-router-k8s-service.database.svc.cluster.local -P 6446 -u relation-7_4fc92c2813524d6-8 -pVRLNoVx6Br4Vn5SNHdoMK52Q
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
3 rows in set (0.01 sec)
mysql> exit;
Bye
root@data-integrator-0:/var/lib/juju# mysql -h mysql-router-k8s-service.database.svc.cluster.local -P 6447 -u relation-7_4fc92c2813524d6-8 -pVRLNoVx6Br4Vn5SNHdoMK52Q
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
3 rows in set (0.01 sec)
External Access¶
MySQL Router K8s can be made externally accessible by setting expose-external=nodeport (corresponding to K8s NodePort service) or expose-external=loadbalancer (corresponding to K8s LoadBalancer service).
When expose-external=nodeport, MySQL Router K8s will provide as endpoints comma-separated node:port values of the nodes where the MySQL Router K8s units are scheduled.
$ juju run data-integrator/0 get-credentials
mysql:
data: '{"database": "test-database", "external-node-connectivity": "true", "requested-secrets":
"[\"username\", \"password\", \"tls\", \"tls-ca\", \"uris\"]"}'
database: test-database
endpoints: 10.0.0.44:31604
password: VRLNoVx6Br4Vn5SNHdoMK52Q
read-only-endpoints: 10.0.0.44:31907
username: relation-7_4fc92c2813524d6-8
ok: "True"
$ charmed-mysql.mysql -h 10.0.0.44 -P 31604 -u relation-7_4fc92c2813524d6-8 -pVRLNoVx6Br4Vn5SNHdoMK52Q
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
3 rows in set (0.00 sec)
$ charmed-mysql.mysql -h 10.0.0.44 -P 31907 -u relation-7_4fc92c2813524d6-8 -pVRLNoVx6Br4Vn5SNHdoMK52Q
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
3 rows in set (0.00 sec)
Similarly, when expose-external=loadbalancer, MySQL Router K8s will provide as endpoints comma-separated node:port values of the load balancer nodes associated with the MySQL Router K8s service.
$ juju run data-integrator/0 get-credentials
mysql:
data: '{"database": "test-database", "external-node-connectivity": "true", "requested-secrets":
"[\"username\", \"password\", \"tls\", \"tls-ca\", \"uris\"]"}'
database: test-database
endpoints: 10.0.0.44:6446
password: VRLNoVx6Br4Vn5SNHdoMK52Q
read-only-endpoints: 10.0.0.44:6447
username: relation-7_4fc92c2813524d6-8
ok: "True"
$ charmed-mysql.mysql -h 10.0.0.44 -P 6446 -u relation-7_4fc92c2813524d6-8 -pVRLNoVx6Br4Vn5SNHdoMK52Q
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
3 rows in set (0.00 sec)
$ charmed-mysql.mysql -h 10.0.0.44 -P 6447 -u relation-7_4fc92c2813524d6-8 -pVRLNoVx6Br4Vn5SNHdoMK52Q
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| performance_schema |
| test-database |
+--------------------+
3 rows in set (0.00 sec)
Note
The K8s service created by MySQL Router K8s is owned by the K8s StatefulSet that represents the MySQL Router K8s juju application. Thus, the K8s service is cleaned up when the MySQL Router K8s application is removed.