How to use PostgreSQL and MongoDB Flex with Kubernetes Engine

The following article describes the integration of PostgreSQL Flex and MongoDB Flex services with your STACKIT Kubernetes Engine (SKE) cluster.

Prerequisites

• You already have an SKE cluster. If you haven’t created one, follow the Getting started documentation.
• Permissions to access the STACKIT Cloud Portal and the OpenStack CLI.
• Basic familiarity with Kubernetes and kubectl.

Get the IP of your clusters router

To allow your SKE cluster to connect to the database, you must determine its public egress IP address and add it to the database instance’s access control list (ACL).

Via the STACKIT CLoud Portal

• Go to Networking > Routers.
• Select the router named after your cluster.
• Go to interfaces.
• There will be two entries. One is a Private IP Address (10.x.x.x) and the other is your routers Public IP Address. You need your Public IP Address.

Via OpenStack CLI

• Go to Infrastructure API in the Access section.
• Create a user access token.
• Download your openrc file and source it.

source $HOME/Downloads/openrc

List your routers

openstack router list

The result will look like this

+--------------------------------------+--------------------------------+--------+-------+----------------------------------+
| ID | Name | Status | State | Project |
+--------------------------------------+--------------------------------+--------+-------+----------------------------------+
| b4505724-9387-46aa-acc0-39f6b8f0f064 | shoot--c1fe92c6ca--cl-ysscfu28 | ACTIVE | UP | ef6d65ccc54640a5b4371d5cad8e95ed |
+--------------------------------------+--------------------------------+--------+-------+----------------------------------+

Get your routers Public IP Address

openstack router show <ROUTER-ID>

The result will look like this

+-------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+-------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| admin_state_up | UP |
| availability_zone_hints | |
| availability_zones | |
| created_at | 2023-07-03T13:03:35Z |
| description | |
| enable_ndp_proxy | None |
| c | {"network_id": "970ace5c-458f-484a-a660-0903bcfd91ad", "external_fixed_ips": [{"subnet_id": "599b9753-d6aa-4062-9489-707744e07004", "ip_address": "45.135.247.50"}], "enable_snat": true} |
| flavor_id | None |
| id | b4505724-9387-46aa-acc0-39f6b8f0f064 |
| interfaces_info | [{"port_id": "b444cbc1-8358-49bf-82a7-0aeaa3319141", "ip_address": "10.250.0.1", "subnet_id": "7feed2f4-5925-475b-ad4b-d2345fbadb53"}] |
| name | shoot--c1fe92c6ca--cl-ysscfu28 |
| project_id | ef6d65ccc54640a5b4371d5cad8e95ed |
| revision_number | 4 |
| routes | |
| status | ACTIVE |
| tags | |
| tenant_id | ef6d65ccc54640a5b4371d5cad8e95ed |
| updated_at | 2023-07-03T13:04:10Z |
+-------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

You can find your Public IP Address under external\_fixed\_ips → external\_gateway\_info → ip\_address.

You could also get your Public IP with this command

openstack router show $(openstack router list -f json | jq ".[0].ID" -r) -f json | jq ".external_gateway_info.external_fixed_ips[0].ip_address"

• Create a PostgreSQL Flex instance or MongoDB Flex instance and add your Public IP Address to the ACL IP list with CIDR /32 <PUBLIC-IP>/32
• Create a user to access the instance
• Copy your URI
• Create a secret containing your URI or username and password as needed

kubectl create secret generic postgres-connection \
 --from-literal=POSTGRES_URI='<postgres-uri>'

kubectl create secret generic postgres-connection \
 --from-literal=POSTGRES_HOST=<postgres-host> \
 --from-literal=POSTGRES_PORT=<postgres-port> \
 --from-literal=POSTGRES_DATABASE=<postgres-database> \
 --from-literal=POSTGRES_USER=<postgres-user> \
 --from-literal=POSTGRES_PASSWORD=<postgres-password>

Use the secret in your application.